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\pdf_title "SDCC Compiler User Guide"
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\pdf_subject "installation, user manual"
\pdf_keywords "68hc08 8032 8051 ansi iso c compiler assembler CPU DS390 embedded development free Floating Point Arithmetic Freescale GPL HC08 S08 inline Intel ISO/IEC 9899:1990 Linux MAC OS X manual Maxim mcs51 Microchip microcontroller open source PIC Unix Windows Z80 Z180 Zilog Rabbit"
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Two resp.
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Architecture specific stuff (like memory models,
 code examples) should maybe later go
\end_layout

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into separate sections/chapters/appendices (it is hard to document PIC or Z80 in 
\end_layout

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a 8051 centered document) - for now simply add.
\end_layout

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\begin_layout Title
SDCC Compiler User Guide
\end_layout

\begin_layout Date

\size normal
SDCC 
\begin_inset CommandInset include
LatexCommand input
filename "sdcc_version"
literal "true"

\end_inset


\begin_inset Newline newline
\end_inset


\size footnotesize
$Date::
 2024-01-29 #$ 
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$Revision:
 14650 $
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The above strings enclosed in $ are automatically updated by Subversion
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\begin_layout Chapter
Introduction
\end_layout

\begin_layout Section
About SDCC
\end_layout

\begin_layout Standard

\series bold
SDCC
\series default
 (
\emph on
S
\emph default
mall 
\emph on
D
\emph default
evice 
\emph on
C
\emph default
 
\emph on
C
\emph default
ompiler) is free open source,
 retargettable,
 optimizing standard (ANSI C89 / ISO C90,
 ISO C99,
 ISO C11 / ISO C17) C compiler suite originally written by 
\series bold
Sandeep Dutta
\series default
 designed for 8 bit Microprocessors.
 The current version targets Intel MCS-51 based Microprocessors (8031,
 8032,
 8051,
 8052
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status collapsed

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8031,
 8032,
 8051,
 8052,
 mcs51 CPU
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,
 etc.),
 Dallas DS80C390 variants,
 NXP (formerly Freescale/Motorola) HC08 based (HC08,
 S08),
 Zilog Z80 based MCUs (Z80,
 Z180,
 eZ80 in Z80 mode,
 SM83,
 Rabbit 2000/3000,
 Rabbit 3000A ,
 Toshiba TLCS-90,
 Zilog eZ80 in Z80 mode,
 ASCII R800
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Z80,
 Z180,
 SM83,
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),
 STMicroelectronics STM8 
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,
 Padauk PDK14 and PDK15.
 It can be retargeted for other microprocessors;
 support for Padauk PDK13 and MOS6502 is under development,
 whereas Microchip PIC is currently unmaintained.
 The entire source code for the compiler is distributed under GPL.
 SDCC uses a modified version of ASXXXX
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sdas (sdasgb,
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 & ASLINK
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sdld
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,
 free open source retargetable assembler & linker.
 SDCC has extensive language extensions suitable for utilizing various microcontrollers and underlying hardware effectively.
 
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You might also want to have a look at the wiki 
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https://sourceforge.net/p/sdcc/wiki/
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.
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In addition to the MCU specific optimizations SDCC also does a host of standard optimizations like:
\end_layout

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global sub expression elimination,
 
\end_layout

\begin_layout Itemize
loop optimizations (loop invariant,
 strength reduction of induction variables and loop reversing),
 
\end_layout

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constant folding & propagation,
 
\end_layout

\begin_layout Itemize
copy propagation,
 
\end_layout

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dead code elimination 
\end_layout

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jump tables for 
\emph on
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\emph default
 statements.
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For the back-end SDCC uses a global register allocation scheme which should be well suited for other 8 bit MCUs.
\begin_inset Newline newline
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The peep hole optimizer uses a rule based substitution mechanism which is MCU independent.
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Supported data-types are:
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1.175494351E-38,
 
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Only supported in the mcs51,
 ds390,
 ds400 backends.
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The compiler also allows 
\emph on
inline assembler code
\emph default
 to be embedded anywhere in a function.
 In addition,
 routines developed in assembly can also be called.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

SDCC also provides an option (-
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\backslash
/
\end_layout

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-cyclomatic) to report the relative complexity of a function.
 These functions can then be further optimized,
 or hand coded in assembly if needed.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

SDCC also comes with a companion source level debugger SDCDB.
 The debugger currently uses ucSim,
 a free open source simulator for 8051 and other micro-controllers.
\begin_inset Newline newline
\end_inset


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\end_inset

The latest SDCC version can be downloaded from 
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http://sdcc.sourceforge.net/snap.php
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.
 
\emph on
Please note:
 the compiler will probably always be some steps ahead of this documentation
\series bold
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Status of documentation
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Obviously this has pros and cons
\end_layout

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.
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\begin_layout Section
SDCC Suite Licenses
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SDCC suite is a collection of several components derived from different sources with different licenses:
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executables:
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\begin_deeper
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sdcc compiler:
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\end_inset

sdcc compiler is licensed under the GPLv2 (GPLv3 might apply depending on the libraries used when building).
\begin_inset Newline newline
\end_inset

The code or object files generated by SDCC suite are not licensed,
 so they can be used in FLOSS or proprietary (closed source) applications.
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sdcpp preprocessor:
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\end_inset

derived from GCC cpp preprocessor 
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status collapsed

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http://gcc.gnu.org/
\end_layout

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;
 GPLv3 license
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sdas assemblers and sdld linker:
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derived from ASXXXX 
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status collapsed

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https://shop-pdp.net/ashtml/
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;
 GPLv3 license
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SDCC run-time libraries:
\begin_inset Newline newline
\end_inset

The great majority of SDCC run-time libraries are licensed under the GPLv2+LE
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
GPLv2+LE
\end_layout

\end_inset

 which allows linking of SDCC run-time libraries with proprietary (closed source) applications.
\begin_inset Newline newline
\end_inset

A possible exception are pic device libraries and header files which are generated from Microchip header (.inc) and linker script (.lkr) files.
 Microchip requires that "The header files should state that they are only to be used with authentic Microchip devices" which makes them incompatible with the GPL,
 if Microchip has any copyright in them (which might depend on local copyright laws).
 Pic device libraries and header files are located at non-free/lib and non-free/include directories respectively.
 SDCC should be run with the 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\series default
use-non-free
\series bold

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\end_layout

\end_inset


\series default
 command line option in order to include non-free header files and libraries.
 
\end_layout

\begin_layout Itemize
sdbinutils utilities (sdar,
 sdranlib,
 sdnm,
 sdobjcopy):
\begin_inset Newline newline
\end_inset

derived from GNU Binutils 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.gnu.org/software/binutils/
\end_layout

\end_inset

;
 GPLv3 license
\end_layout

\begin_layout Itemize
ucsim simulators:
\begin_inset Newline newline
\end_inset

GPLv2 license
\end_layout

\begin_layout Itemize
sdcdb debugger:
\begin_inset Newline newline
\end_inset

GPLv2 license
\end_layout

\begin_layout Itemize
gcc-test regression tests:
\begin_inset Newline newline
\end_inset

derived from gcc-testsuite;
 no license explicitely specified,
 but since it is a part of GCC is probably GPLv3 licensed
\end_layout

\begin_layout Itemize
packihx:
\begin_inset Newline newline
\end_inset

public domain
\end_layout

\begin_layout Itemize
makebin:
\begin_inset Newline newline
\end_inset

zlib/libpng License
\end_layout

\begin_layout Itemize
pic libraries in device/non-free:
\begin_inset Newline newline
\end_inset

Microchip Technology Inc.
\begin_inset space \space{}
\end_inset

claims to have copyrights on this,
 and their term are non-free.
 However,
 a more common opinion is that Microchip Technology Inc.
\begin_inset space \space{}
\end_inset

is just claiming a copyright on uncopyrightable facts.
\end_layout

\end_deeper
\begin_layout Itemize
libraries:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_deeper
\begin_layout Itemize
dbuf library:
\begin_inset Newline newline
\end_inset

zlib/libpng License
\end_layout

\begin_layout Itemize
Boost C++ libraries:
\begin_inset Newline newline
\end_inset


\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.boost.org/
\end_layout

\end_inset

;
 Boost Software License 1.0 (BSL-1.0)
\end_layout

\end_deeper
\begin_layout Standard
Links to licenses:
\end_layout

\begin_layout Itemize
GPLv2 license
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
GPLv2 license
\end_layout

\end_inset

:
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
LGPLv2.1 license
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
LGPLv2.1 license
\end_layout

\end_inset

:
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
GPLv3 license
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
GPLv3 license
\end_layout

\end_inset

:
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.gnu.org/licenses/gpl.html
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
zlib/libpng License
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
zlib/libpng License
\end_layout

\end_inset

:
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.opensource.org/licenses/Zlib
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
Boost Software License 1.0 (BSL-1.0)
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Boost Software License 1.0 (BSL-1.0)
\end_layout

\end_inset

:
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.opensource.org/licenses/BSL-1.0
\end_layout

\end_inset


\end_layout

\begin_layout Section
Documentation
\end_layout

\begin_layout Standard
This documentation is maintained using a free open source word processor (\SpecialChar LyX
) 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.lyx.org/
\end_layout

\end_inset

.
\end_layout

\begin_layout Section
Typographic conventions
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Typographic conventions
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Throughout this manual,
 we will use the following convention.
 Commands you have to type in are printed in 
\family sans
\series bold
"sans serif"
\series default
.

\family default
 Code samples are printed in 
\family typewriter
typewriter font.

\family default
 Interesting items and new terms are printed in 
\emph on
italic.
\end_layout

\begin_layout Section
Compatibility
\begin_inset CommandInset label
LatexCommand label
name "sec:Compatibility-with-previous"

\end_inset

 with previous versions
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Compatibility with previous versions
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Newer versions have usually numerous bug fixes compared with the previous version.
 But we also sometimes introduce some incompatibilities with older versions.
 Not just for the fun of it,
 but to make the compiler more stable,
 efficient and standard compliant
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Standard-compliance
\end_layout

\end_inset

 (see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Standard-Compliance"
nolink "false"

\end_inset

 for Standard-Compliance).
 This is a list of such changes .
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
It would be fine to add to each item,
 in which version was it changed.
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
short is now equivalent to int (16 bits),
 it used to be equivalent to char (8 bits) which is not ANSI compliant.
 To maintain compatibility,
 old programs could be compiled using the -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-short-is-8bits command line option (option removed after the 3.6.0 release).
\end_layout

\begin_layout Itemize
the default directory for gcc-builds where include,
 library and documentation files are stored is now in /usr/local/share.
\end_layout

\begin_layout Itemize
char type parameters to vararg
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
vararg,
 va
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

arg
\end_layout

\end_inset

 functions are casted to int unless explicitly casted and neither of the 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-std-c90
\begin_inset Index idx
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status open

\begin_layout Plain Layout
-
\begin_inset ERT
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\begin_layout Plain Layout


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\end_layout

\end_inset

-std-c90
\end_layout

\end_inset

,

\series default
 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


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\end_layout

\end_inset

-std-c99
\begin_inset Index idx
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-
\begin_inset ERT
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\begin_layout Plain Layout


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\end_layout

\end_inset

-std-c99
\end_layout

\end_inset

,
 -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


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\end_layout

\end_inset

-std-c11
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\begin_layout Plain Layout
-
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\begin_layout Plain Layout


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-std-c11
\end_layout

\end_inset


\series default
 or 
\series bold
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\end_layout

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-std-c23
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-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-std-c23
\end_layout

\end_inset


\series default
 command line options is used,
 e.g.:
 
\begin_inset Newline newline
\end_inset


\family typewriter

\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

char a=3;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

printf ("%d %c
\backslash
n",
 a,
 (char)a);
\family default

\begin_inset Newline newline
\end_inset

 will push a as an int and as a char resp if none of the above command line options are not defined,
\begin_inset Newline newline
\end_inset

 will push a as two ints if none of the above command line option is defined.
\end_layout

\begin_layout Itemize
pointer type parameters to vararg
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
vararg,
 va
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

arg
\end_layout

\end_inset

 functions are casted to generic pointers on Harvard architectures (e.g.
 mcs51,
 ds390) unless explicitly casted and neither of the 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-std-c90
\begin_inset Index idx
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status open

\begin_layout Plain Layout
-
\begin_inset ERT
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\end_layout

\end_inset

-std-c90
\end_layout

\end_inset

,

\series default
 
\series bold
-
\begin_inset ERT
status collapsed

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\end_layout

\end_inset

-std-c99
\begin_inset Index idx
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-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-std-c99
\end_layout

\end_inset

,
 -
\begin_inset ERT
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\begin_layout Plain Layout


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/
\end_layout

\end_inset

-std-c11
\begin_inset Index idx
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\begin_layout Plain Layout
-
\begin_inset ERT
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-std-c11
\end_layout

\end_inset


\series default
 or 
\series bold
-
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-std-c23
\begin_inset Index idx
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-
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\end_layout

\end_inset

-std-c23
\end_layout

\end_inset


\series default
 command line options is used.
\end_layout

\begin_layout Itemize
option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-regextend has been removed.
\end_layout

\begin_layout Itemize
option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-noregparms has been removed.
\end_layout

\begin_layout Itemize
option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-after-data has been removed.
\end_layout

\begin_layout Itemize
__bit
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

bit
\end_layout

\end_inset

 and __sbit
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sbit
\end_layout

\end_inset

 types now consistently behave like the C99 _Bool type with respect to type conversion
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
type conversion
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
type promotion
\end_layout

\end_inset

.
 The most common incompatibility resulting from this change is related to bit toggling
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Bit toggling
\end_layout

\end_inset

 idioms,
 e.g.:
\begin_inset Newline newline
\end_inset


\family typewriter

\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__bit b;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

b = ~
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
~ Operator
\end_layout

\end_inset

b;
 /* equivalent to b=1 instead of toggling b */
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

b = !b;
 /* toggles b */
\begin_inset Newline newline
\end_inset


\family default
In previous versions,
 both forms would have toggled the bit.
\end_layout

\begin_layout Itemize
in older versions,
 the preprocessor was always called with 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-std-c99
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-std-c99
\end_layout

\end_inset


\series default
 regardless of the 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-std-xxx
\series default
 setting.
 This is no longer true,
 and can cause compilation failures on code built with 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-std-c90
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-std-c90
\end_layout

\end_inset


\series default
 but using c99 preprocessor features,
 such as one-line (//) comments
\end_layout

\begin_layout Itemize
in versions older than 2.8.4 the pic16 *printf() and printf_tiny() library functions supported undocumented and not standard compliant 'b' binary format specifier ("%b",
 "%hb" and "%lb").
 The 'b' specifier is now disabled by default.
 It can be enabled by defining BINARY_SPECIFIER macro in files device/lib/pic16/libc/stdio/vfprintf.c and device/lib/pic16/libc/stdio/printf_tiny.c and recompiling the library.
\end_layout

\begin_layout Itemize
in versions older then 2.8.5 the unnamed bit-field structure members participated in initialization,
 which is not conforming with ISO/IEC 9899:1999 standard (see section Section 6.7.8 Initialization,
 clause 9)
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Old behaviour,
 before version 2.8.5:
\family typewriter

\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

struct {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

int a :
 2;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

char
\begin_inset space ~
\end_inset

 :
 2;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

int b :
 2;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

} s = {1,
 2,
 3};
\family default

\begin_inset Newline newline
\end_inset


\family typewriter
/* s.a = 1,
 s.b = 3 */
\family default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

New behaviour:
\family typewriter

\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

struct {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

int a :
 2;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

char
\begin_inset space ~
\end_inset

 :
 2;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

int b :
 2;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

} s = {1,
 2};
\family default

\begin_inset Newline newline
\end_inset


\family typewriter
/* s.a = 1,
 s.b = 2 */
\end_layout

\begin_layout Itemize
In 2.9.0 libraries included in SDCC packages,
 are in ar format.
 See section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Using-sdar-to"
nolink "false"

\end_inset

.
\end_layout

\begin_layout Itemize
In 3.0.0 targets for xa51 and avr are disabled by default.
\end_layout

\begin_layout Itemize
In 3.0.0 sdldgb and sdldz80 don't support generation of Game Boy binary image format.
 The makebin utility can be used to convert Intel Hex format to Game Boy binary image format.
\end_layout

\begin_layout Itemize
In 3.0.0 sdldgb and sdldz80 don't support generation of rrgb (Game Boy simulator) map file and no$gmb symbol file formats.
 The as2gbmap utility can be used to convert sdld map format to rrgb and no$gmb file formats.
\end_layout

\begin_layout Itemize
In 3.1.0 asranlib utility was renamed to sdranlib.
\end_layout

\begin_layout Itemize
In 3.1.0 pic14 target,
 structured access to SFR via 
\family typewriter
<sfrname>_bits.<bitname>
\family default
 is deprecated and replaced by 
\family typewriter
<sfrname>bits.<bitname>
\family default
.
 It will be obsoleted (removed) in one of next SDCC releases.
 See section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Naming-of-special"
nolink "false"

\end_inset

.
\end_layout

\begin_layout Itemize
sdar archive managing utility and sdnm utilities were introduced in version 3.2.0.
 sdar,
 sdranlib and sdnm are derived from GNU Binutils package.
\end_layout

\begin_layout Itemize
In 3.2.0 the sdcclib utility is deprecated.
 Sdar utility should be used to create SDCC object file archives.
 Sdcclib utility will become obsolete in one of next SDCC releases and will be removed from SDCC packages.
\end_layout

\begin_layout Itemize
In 3.2.0 special SDCC keywords which are not preceded by a double underscore are obsoleted (removed).
 See section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Standard-Compliance"
nolink "false"

\end_inset

 Standard-Compliance.
\end_layout

\begin_layout Itemize
In 3.2.0 compiler macro definitions not starting with double underscore characters are deprecated if 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--std-cXX
\end_layout

\end_inset

 command line option is defined.
 They have been obsoleted (removed) after the 3.4.0 release (except for the macro SDCC,
 which has been removed after the 3.6.0 release (and brought back for mcs51 for the 3.7.0 release)).
\end_layout

\begin_layout Itemize
In 3.2.0 new compiler macros for processor definition were introduced for pic14 and pic16 targets:
 -D__SDCC_PIC16XXXX and -D__SDCC_PIC18FXXX respectively.
 The pic16 macro definition -D__18fXXX is deprecated.
 It was obsoleted (removed) after the 3.4.0 release.
\end_layout

\begin_layout Itemize
In 3.2.0 pragma config for pic16 target was introduced.
 See section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:PIC16_Pragmas"
nolink "false"

\end_inset


\end_layout

\begin_layout Itemize
In 3.2.0 new inline assembler format 
\family typewriter
__asm__ (
\begin_inset Quotes sld
\end_inset

inline_assembler_code
\begin_inset Quotes srd
\end_inset

);

\family default
 as an addition to 
\family typewriter
__asm ...
 __endasem;

\family default
 format introduced.
 See section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Inline-Assembler-Code"
nolink "false"

\end_inset


\end_layout

\begin_layout Itemize
sdobjcopy utility was introduced in version 3.3.0.
 It is derived from GNU Binutils package.
\end_layout

\begin_layout Itemize
Before 3.4.0 release,
 intrinsic named address spaces were called 
\begin_inset Quotes sld
\end_inset

storage classes
\begin_inset Quotes srd
\end_inset

 in this manual.
\end_layout

\begin_layout Itemize
In 3.6.0,
 the default for char changed from signed to unsigned.
\end_layout

\begin_layout Itemize
In 3.7.0,
 the prototype for putchar() changed from void putchar(char) to int putchar(int).
\end_layout

\begin_layout Itemize
In 3.7.0 mcs51 and ds390 got a full _Bool/bool type,
 separate from __bit.
\end_layout

\begin_layout Itemize
In 3.7.0,
 the option 
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status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nojtbound
\series default
 and the corresponding pragma have been deprecated.
\end_layout

\begin_layout Itemize
In 3.7.0,
 the prototype for getchar() changed from char getchar(void) to int getchar(void).
\end_layout

\begin_layout Itemize
In 3.8.6,
 the deprecated sdcclib was removed.
\end_layout

\begin_layout Itemize
In 4.0.3,
 _itoa,
 _uitoa,
 _ltoa,
 _ultoa were renamed to __itoa,
 __uitoa,
 __ltoa,
 __ultoa.
\end_layout

\begin_layout Itemize
In 4.1.1,
 typeof.h has been removed.
\end_layout

\begin_layout Itemize
In 4.1.3,
 support for 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-oldralloc
\series default
 has been removed for the z80-related backends.
\end_layout

\begin_layout Itemize
In 4.1.10,
 the default calling convention switched from __sdccall(0) to __sdccall(1) for stm8 and gbz80.
\end_layout

\begin_layout Itemize
In 4.1.10,
 support for
\series bold
 -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-profile
\series default
 has been removed for gbz80.
\end_layout

\begin_layout Itemize
In 4.1.11,
 the minimum Z80N Core version for the z80n port has been raised from 1.0 to 2.0.
\end_layout

\begin_layout Itemize
In 4.1.12,
 the default calling convention switched from __sdccall(0) to __sdccall(1) for z80,
 z180 and z80n.
\end_layout

\begin_layout Itemize
In 4.1.12,
 support for 
\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-profile
\series default
 has been removed for z80,
 z180,
 z80n.
\end_layout

\begin_layout Itemize
In 4.1.13,
 support for 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-profile
\series default
 has been removed.
\end_layout

\begin_layout Itemize
In 4.1.14,
 the gbz80 port was renamed to sm83.
\end_layout

\begin_layout Itemize
In 4.2.3,
 support for non-parenthesized arguments to __using and __interrupt was dropped.
\end_layout

\begin_layout Itemize
In 4.2.3,
 support for non-parenthesized arguments to __at that are not constants was dropped.
\end_layout

\begin_layout Itemize
In 4.2.4,
 the placement of __at in declarations was restricted.
\end_layout

\begin_layout Itemize
In 4.2.6,
 bool is chosen as the underlying integer type for enumerations with just two values.
\end_layout

\begin_layout Itemize
In 4.2.9,
 support for
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-pedantic-parse-number
\series default
 and #pragma pedantic_parse_numer was dropped.
\end_layout

\begin_layout Itemize
In 4.2.9,
 support for #pragma sdcc_hash was dropped,
 necessitating a wrapper macro for literal 
\begin_inset Quotes sld
\end_inset

#
\begin_inset Quotes srd
\end_inset

 characters in macro bodies.
\end_layout

\begin_layout Itemize
In 4.2.9,
 support for arguments to -MMD was dropped.
 The output file can be specified via -MF instead.
\end_layout

\begin_layout Itemize
In 4.2.10,
 _sdcc_external_startup was renamed to __sdcc_external_startup and support for it was added to further ports.
\end_layout

\begin_layout Itemize
In 4.2.13,
 for the sm83 port,
 __sfr addresses need to be specified using the full 16-bit address.
\end_layout

\begin_layout Itemize
In 4.2.14,
 byte order in output from the %p specifier of printf()-family functions was corrected for big-endian platforms (stm8,
 hc08,
 s08,
 mos6502) to match uintptr_t.
\end_layout

\begin_layout Itemize
In 4.3.1,
 __builtin_rlc,
 __builtin_rrc and __builtin_swap were replaced by __builtin_rot.
\end_layout

\begin_layout Itemize
In 4.3.6,
 support for 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-parms-in-bank1
\series default
 was removed from the mcs51 port.
\end_layout

\begin_layout Itemize
In 4.4.1,
 the address width in .rel files was increased from 24 bits to 32 bits for the z80 (and related) ports.
\end_layout

\begin_layout Section
System Requirements
\end_layout

\begin_layout Standard
What do you need before you start installation of SDCC?
 A computer,
 and a desire to compute.
 The preferred method of installation is to compile SDCC from source using GNU GCC and make.
 For Windows some pre-compiled binary distributions are available for your convenience.
 You should have some experience with command line tools and compiler use.
\end_layout

\begin_layout Section
Other Resources
\end_layout

\begin_layout Standard
The SDCC home page at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/
\end_layout

\end_inset

 is a great place to find distribution sets.
 You can also find links to the user mailing lists that offer help or discuss SDCC with other SDCC users.
 Web links to other SDCC related sites can also be found here.
 This document can be found in the doc directory of the source package.
 The latest snapshot build version of this document in pdf format is available at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/doc/sdccman.pdf
\end_layout

\end_inset

.
 Some of the other tools (simulator and assembler) included with SDCC contain their own documentation and can be found in the source distribution.
 If you want the latest unreleased software,
 the complete source package is available directly from Subversion on 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/p/sdcc/code/8805/tree/trunk/sdcc/
\end_layout

\end_inset

.
\end_layout

\begin_layout Chapter
Installing SDCC
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Installation
\end_layout

\end_inset


\end_layout

\begin_layout Standard
For most users it is sufficient to skip to either section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Building-SDCC-on-Linux"
nolink "false"

\end_inset

 (Unix) or section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Windows-Install"
nolink "false"

\end_inset

 (Windows).
 More detailed instructions follow below.
\end_layout

\begin_layout Section
Configure Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options SDCC configuration
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The install paths,
 search paths and other options are defined when running 'configure'.
 The defaults can be overridden by:
\end_layout

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\labelwidthstring 00.00.0000
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-prefix see table below
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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-exec_prefix see table below
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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-bindir see table below
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-datadir see table below
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\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-datarootdir see table below
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

docdir environment variable,
 see table below
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

include_dir_suffix environment variable,
 see table below
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

non_free_include_dir_suffix environment variable,
 see table below
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

lib_dir_suffix environment variable,
 see table below
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

non_free_lib_dir_suffix environment variable,
 see table below
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdccconf_h_dir_separator environment variable,
 either / or 
\backslash

\backslash
 makes sense here.
 This character will only be used in sdccconf.h;
 don't forget it's a C-header,
 therefore a double-backslash is needed there.
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-mcs51-port Excludes the Intel mcs51 port
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-disable-ez80_z80-port Excludes the e80_z80 port
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-r800-port Excludes the r800 port
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-r2k-port Excludes the r2k port
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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-disable-tlcs90-port Excludes the TLCS-90 port
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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-hc08-port Excludes the HC08 port
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-pdk13-port Excludes the PDK13 port
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-pdk15-port Excludes the PDK15 port
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-pic16-port Excludes the PIC16 port
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-ucsim Disables configuring and building of ucsim
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-device-lib Disables automatically building device libraries
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-packihx Disables building packihx
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-enable-doc Build pdf,
 html and txt files from the lyx sources
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-enable-libgc Use the Bohem memory allocator.
 Lower runtime footprint.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-without-ccache Do not use ccache even if available
\end_layout

\begin_layout Standard
Furthermore the environment variables CC,
 CFLAGS,
 ...
 the tools and their arguments can be influenced.
 Please see `configure -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-help' and the man/info pages of `configure' for details.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The names of the standard libraries STD_LIB,
 STD_INT_LIB,
 STD_LONG_LIB,
 STD_FP_LIB,
 STD_DS390_LIB,
 STD_XA51_LIB and the environment variables SDCC_DIR_NAME,
 SDCC_INCLUDE_NAME,
 SDCC_LIB_NAME are defined by `configure' too.
 At the moment it's not possible to change the default settings (it was simply never required).
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

These configure options are compiled into the binaries,
 and can only be changed by rerunning 'configure' and recompiling SDCC.
 The configure options are written in 
\emph on
italics
\emph default
 to distinguish them from run time environment variables (see section search paths).
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The settings for 
\begin_inset Quotes sld
\end_inset

Win32 builds
\begin_inset Quotes srd
\end_inset

 are used by the SDCC team to build the official Win32 binaries.
 The SDCC team uses Mingw32 to build the official Windows binaries,
 because it's
\end_layout

\begin_layout Enumerate
open source,
 
\end_layout

\begin_layout Enumerate
a gcc compiler and last but not least
\end_layout

\begin_layout Enumerate
the binaries can be built by cross compiling on SDCC Distributed Compile Farm.
\end_layout

\begin_layout Standard
See the examples,
 how to pass the Win32 settings to 'configure'.
 The other Win32 builds using VC or whatever don't use 'configure',
 but a header file sdcc_vc.h.in is the same as sdccconf.h built by 'configure' for Win32.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

These defaults are:
\begin_inset Newline newline
\end_inset


\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="11" columns="3">
<features tabularvalignment="middle">
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Examples:
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./configure
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./configure -
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status collapsed

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\backslash
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status collapsed

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\backslash
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To cross compile on linux for Mingw32 (see also 'sdcc/support/scripts/sdcc_mingw32'):
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./configure 
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CC=
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i586-mingw32msvc-gcc
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 CXX=
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i586-mingw32msvc-g++
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RANLIB=
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i586-mingw32msvc-ranlib
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\backslash

\begin_inset Newline newline
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STRIP=
\begin_inset Quotes srd
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i586-mingw32msvc-strip
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-
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status collapsed

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\backslash

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\end_inset

 
\backslash

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docdir=
\begin_inset Quotes srd
\end_inset


\backslash
${datarootdir}/doc
\begin_inset Quotes srd
\end_inset

 
\backslash

\begin_inset Newline newline
\end_inset

include_dir_suffix=
\begin_inset Quotes srd
\end_inset

include
\begin_inset Quotes srd
\end_inset

 
\backslash

\begin_inset Newline newline
\end_inset

non_free_include_dir_suffix=
\begin_inset Quotes srd
\end_inset

non-free/include
\begin_inset Quotes srd
\end_inset

 
\backslash

\begin_inset Newline newline
\end_inset

lib_dir_suffix=
\begin_inset Quotes srd
\end_inset

lib
\begin_inset Quotes srd
\end_inset

 
\backslash

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\end_inset

non_free_lib_dir_suffix=
\begin_inset Quotes srd
\end_inset

non-free/lib
\begin_inset Quotes srd
\end_inset

 
\backslash

\begin_inset Newline newline
\end_inset

sdccconf_h_dir_separator=
\begin_inset Quotes srd
\end_inset


\backslash

\backslash

\backslash

\backslash

\begin_inset Quotes srd
\end_inset

 
\backslash

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\end_inset

-
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status collapsed

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\backslash
/
\end_layout

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-disable-device-lib 
\backslash

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-
\begin_inset ERT
status collapsed

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\backslash
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-host=i586-mingw32msvc 
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-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-build=unknown-unknown-linux-gnu
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\begin_layout Standard
To 
\begin_inset Quotes sld
\end_inset

cross
\begin_inset Quotes srd
\end_inset

compile on Cygwin for Mingw32 (see also sdcc/support/scripts/sdcc_cygwin_mingw32):
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./configure 
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-
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status collapsed

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\backslash

\begin_inset Newline newline
\end_inset

-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


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/
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-datarootdir=
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/sdcc
\begin_inset Quotes srd
\end_inset

 
\backslash

\begin_inset Newline newline
\end_inset

docdir=
\begin_inset Quotes srd
\end_inset


\backslash
${datarootdir}/doc
\begin_inset Quotes srd
\end_inset

 
\backslash
 
\begin_inset Newline newline
\end_inset

include_dir_suffix=
\begin_inset Quotes srd
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include
\begin_inset Quotes srd
\end_inset

 
\backslash

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non_free_include_dir_suffix=
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non-free/include
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\backslash

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lib
\begin_inset Quotes srd
\end_inset

 
\backslash

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non_free_lib_dir_suffix=
\begin_inset Quotes srd
\end_inset

non-free/lib
\begin_inset Quotes srd
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\backslash

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\end_inset

sdccconf_h_dir_separator=
\begin_inset Quotes srd
\end_inset


\backslash

\backslash

\backslash

\backslash

\begin_inset Quotes srd
\end_inset

 
\backslash

\begin_inset Newline newline
\end_inset

CC=
\begin_inset Quotes srd
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gcc -mno-cygwin
\begin_inset Quotes srd
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\backslash

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\end_inset

CXX=
\begin_inset Quotes srd
\end_inset

g++ -mno-cygwin
\begin_inset Quotes srd
\end_inset

 
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\begin_layout Section
Install paths
\begin_inset CommandInset label
LatexCommand label
name "subsec:Install-paths"

\end_inset


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pageformat default
status collapsed

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Install paths
\end_layout

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\emph on
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\emph on
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\emph default

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\emph on
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\emph on
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\emph default

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\emph on
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\emph default

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\emph on
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\begin_inset Text

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\begin_inset Newline newline
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\emph on
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\begin_inset Newline newline
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\backslash
doc
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\end_inset


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\size footnotesize
*compiler,
 preprocessor,
 assembler,
 and linker
\begin_inset Newline newline
\end_inset

**the 
\shape italic
model
\shape default
 is auto-appended by the compiler,
 e.g.
 small,
 large,
 z80,
 ds390 etc
\end_layout

\begin_layout Standard
\noindent
The install paths can still be changed during `make install' with e.g.:
\end_layout

\begin_layout LyX-Code
make install prefix=$(HOME)/local/sdcc
\end_layout

\begin_layout Standard
Of course this doesn't change the search paths compiled into the binaries.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Moreover the install path can be changed by defining DESTDIR
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DESTDIR
\end_layout

\end_inset

:
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make install DESTDIR=$(HOME)/sdcc.rpm/
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Please note that DESTDIR must have a trailing slash!
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\begin_layout Section
Search Paths
\begin_inset CommandInset label
LatexCommand label
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\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Search path
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Some search paths or parts of them are determined by configure variables (in 
\emph on
italics
\emph default
,
 see section above).
 Further search paths are determined by environment variables during runtime.
 
\begin_inset Newline newline
\end_inset

The paths searched when running the compiler are as follows (the first catch wins):
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

1.
 Binary files (preprocessor,
 assembler and linker)
\begin_inset Newline newline
\end_inset


\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
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<column alignment="block" valignment="top" width="0in">
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\begin_layout Plain Layout
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Win32 builds
\end_layout

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\begin_layout Plain Layout
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\emph on
$PPREFIX2BIN_DIR
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\end_inset
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\begin_inset Text

\begin_layout Plain Layout
$SDCC_HOME/bin
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\backslash
..
\backslash

\begin_inset Newline newline
\end_inset

lib
\backslash
non-free
\emph on

\backslash
<model>
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
9
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\emph on
$DATADIR/non-free/
\emph default

\begin_inset Newline newline
\end_inset


\emph on
$LIB_DIR_SUFFIX/
\emph default

\begin_inset Newline newline
\end_inset


\emph on
<model>
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
/usr/local/share/sdcc/
\begin_inset Newline newline
\end_inset

non-free/lib/
\begin_inset Newline newline
\end_inset


\emph on
<model>
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
(not on Win32)
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
Don't delete any of the stray spaces in the table above without checking the HTML output (last line)!
\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset space ~
\end_inset


\begin_inset Newline newline
\end_inset

The option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nostdlib disables all search paths except #1 and #2.
\end_layout

\begin_layout Section
Building SDCC
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Building SDCC
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC can be built for various host platforms using the instructions provided below.
 Note that the PIC14 and PIC16 library folders in the source distribution contain Autotools-generated files.
 These are included for convenience and to avoid introducing Autotools as an additional dependency.
 They have to be regenerated in case of a version mismatch.
 Alternatively,
 the PIC backends can be disabled.
\end_layout

\begin_layout Subsection
Building SDCC on Linux
\begin_inset CommandInset label
LatexCommand label
name "subsec:Building-SDCC-on-Linux"

\end_inset


\end_layout

\begin_layout Enumerate

\series medium
Download the source package
\series default
 either from the SDCC Subversion repository or from snapshot builds
\series medium
,
 it will be named something like sdcc
\series default
-src
\series medium
-yyyymmdd-rrrr.t
\series default
ar.
\series medium
bz2
\series default
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/snap.php
\end_layout

\end_inset

.
\end_layout

\begin_layout Enumerate

\series medium
Bring up a command line terminal,
 such as xterm.
\end_layout

\begin_layout Enumerate

\series medium
Unpack the file using a command like:

\series default
 
\family sans
\series bold
"tar -xvjf sdcc-src-yyyymmdd-rrrr.tar.bz2
\begin_inset Quotes srd
\end_inset


\family default
\series medium
,
 this will create a sub-directory called sdcc with all of the sources.
\end_layout

\begin_layout Enumerate
Change directory into the main SDCC directory,
 for example type:
 
\family sans
\series bold
"cd sdcc
\series default
".
\end_layout

\begin_layout Enumerate

\series medium
Type
\series default
 
\family sans
\series bold
"./configure
\family default
\series default
".
 This configures the package for compilation on your system.
 When the treedec library is available,
 it should be found and used automatically (improving the compilation time / code quality trade-off).
 As of SDCC 3.7.0,
 the current develop branch from https://github.com/freetdi/tdlib is a suitable version of treedec.
\end_layout

\begin_layout Enumerate

\series medium
Type
\series default
 
\family sans
\series bold
"make
\family default
\series default
"
\series medium
.

\series default
 All of the source packages will compile,
 this can take a while.
\end_layout

\begin_layout Enumerate

\series medium
Type
\series default
 
\family sans
\series bold
"make install"
\family default
\series default
 as root
\series medium
.

\series default
 This copies the binary executables,
 the include files,
 the libraries and the documentation to the install directories.
 Proceed with section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Testing-the-SDCC"
nolink "false"

\end_inset

.
\end_layout

\begin_layout Subsection
Building SDCC on Mac OS X
\end_layout

\begin_layout Standard
Follow the instruction for Linux.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

On Mac OS X 10.2.x it was reported,
 that the default gcc (version 3.1 20020420 (prerelease)) fails to compile SDCC.
 Fortunately there's also gcc 2.9.x installed,
 which works fine.
 This compiler can be selected by running 'configure' with:
\end_layout

\begin_layout LyX-Code
./configure CC=gcc2 CXX=g++2
\end_layout

\begin_layout Standard
Universal (ppc and i386) binaries can be produced on Mac OS X 10.4.x with Xcode.
 Run 'configure' with:
\end_layout

\begin_layout LyX-Code
./configure 
\backslash

\end_layout

\begin_layout LyX-Code
LDFLAGS="-Wl,-syslibroot,/Developer/SDKs/MacOSX10.4u.sdk -arch i386 -arch ppc" 
\backslash

\end_layout

\begin_layout LyX-Code
CXXFLAGS = "-O2 -isysroot /Developer/SDKs/MacOSX10.4u.sdk -arch i386 -arch ppc" 
\backslash

\end_layout

\begin_layout LyX-Code
CFLAGS = "-O2 -isysroot /Developer/SDKs/MacOSX10.4u.sdk -arch i386 -arch ppc"
\end_layout

\begin_layout Subsection
Cross compiling SDCC on Linux for Windows
\end_layout

\begin_layout Standard
With the MinGW gcc cross compiler SDCC can be cross-compiled for Win32.
 See section 'Configure Options'.
 SDCC requires boost,
 but the header-only parts should be sufficient:
 Get a current boost tarball from www.boost.org,
 unpack it,
 and choose suitable configure options so the headers are found by the C++ compiler.
\end_layout

\begin_layout Subsection
Building SDCC using Cygwin and Mingw32
\end_layout

\begin_layout Standard
For building and installing a Cygwin executable follow the instructions for Linux.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

On Cygwin a 
\begin_inset Quotes sld
\end_inset

native
\begin_inset Quotes srd
\end_inset

 Win32-binary can be built,
 which will not need the Cygwin-DLL.
 For the necessary 'configure' options see section 'configure options' or the script 'sdcc/support/scripts/sdcc_cygwin_mingw32'.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

In order to install Cygwin on Windows download setup.exe from www.cygwin.com 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.cygwin.com/
\end_layout

\end_inset

.
 Run it,
 set the 
\begin_inset Quotes sld
\end_inset

default text file type
\begin_inset Quotes srd
\end_inset

 to 
\begin_inset Quotes sld
\end_inset

unix
\begin_inset Quotes srd
\end_inset

 and download/install at least the following packages.
 Some packages are selected by default,
 others will be automatically selected because of dependencies with the manually selected packages.
 Never deselect these packages!
\end_layout

\begin_layout Itemize
flex
\end_layout

\begin_layout Itemize
bison
\end_layout

\begin_layout Itemize
gcc ;
 version 3.x is fine,
 no need to use the old 2.9x
\end_layout

\begin_layout Itemize
binutils ;
 selected with gcc
\end_layout

\begin_layout Itemize
make
\end_layout

\begin_layout Itemize
libboost-dev
\end_layout

\begin_layout Itemize
rxvt ;
 a nice console,
 which makes life much easier under windoze (see below)
\end_layout

\begin_layout Itemize
man ;
 not really needed for building SDCC,
 but you'll miss it sooner or later
\end_layout

\begin_layout Itemize
less ;
 not really needed for building SDCC,
 but you'll miss it sooner or later
\end_layout

\begin_layout Itemize
svn ;
 only if you use Subversion access
\end_layout

\begin_layout Standard
If you want to develop something you'll need:
\end_layout

\begin_layout Itemize
python ;
 for the regression tests
\end_layout

\begin_layout Itemize
gdb ;
 the gnu debugger,
 together with the nice GUI 
\begin_inset Quotes sld
\end_inset

insight
\begin_inset Quotes srd
\end_inset


\end_layout

\begin_layout Itemize
openssh ;
 to access the CF or commit changes
\end_layout

\begin_layout Itemize
autoconf and autoconf-devel ;
 if you want to fight with 'configure',
 don't use autoconf-stable!
\end_layout

\begin_layout Standard
rxvt is a nice console with history.
 Replace in your cygwin.bat the line
\end_layout

\begin_layout LyX-Code
bash -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-login -i 
\end_layout

\begin_layout Standard
with (one line):
\end_layout

\begin_layout LyX-Code
rxvt -sl 1000 -fn "Lucida Console-12" -sr -cr red
\end_layout

\begin_layout LyX-Code
     -bg black -fg white -geometry 100x65 -e bash -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-login
\end_layout

\begin_layout Standard
Text selected with the mouse is automatically copied to the clipboard,
 pasting works with shift-insert.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The other good tip is to make sure you have no //c/-style paths anywhere,
 use /cygdrive/c/ instead.
 Using // invokes a network lookup which is very slow.
 If you think 
\begin_inset Quotes sld
\end_inset

cygdrive
\begin_inset Quotes srd
\end_inset

 is too long,
 you can change it with e.g.
\end_layout

\begin_layout LyX-Code
mount -s -u -c /mnt
\end_layout

\begin_layout Standard
SDCC sources use the unix line ending LF.
 Life is much easier,
 if you store the source tree on a drive which is mounted in binary mode.
 And use an editor which can handle LF-only line endings.
 Make sure not to commit files with Windows line endings.
 The tabulator spacing
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
tabulator spacing (8 columns)
\end_layout

\end_inset

 used in the project is 8.
 Although a tabulator spacing of 8 is a sensible choice for programmers (it's a power of 2 and allows to display 8/16 bit signed variables without loosing columns) the plan is to move towards using only spaces in the source.
\end_layout

\begin_layout Subsection
Building SDCC Using Microsoft Visual C++ 2010 (MSVC)
\end_layout

\begin_layout Standard
TODO:
 This section is outdated.
 Current SDCC requires features noit present in MSVC++ 2010.
 MSVC++ 2019 or newer is required.
\end_layout

\begin_layout Standard

\series medium
Download the source package
\series default
 either from the SDCC Subversion repository or from the snapshot builds 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/snap.php
\end_layout

\end_inset


\series medium
,
 it will be named something like sdcc
\series default
-src
\series medium
-yyyymmdd-rrrr.tar.bz2.

\series default
 SDCC is distributed with all the project,
 solution and other files you need to build it using Visual C++ 2010 (except for ucSim).
 The solution name is 'sdcc.sln'.
 Please note that as it is now,
 all the executables are created in a folder called sdcc
\backslash
bin_vc.
 Once built you need to copy the executables from sdcc
\backslash
bin_vc to sdcc
\backslash
bin before running SDCC.
 
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Apart from the SDCC sources you also need to have the BOOST libraries installed for MSVC.
 Get it here 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.boost.org/
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

In order to build SDCC with MSVC you need win32 executables of bison.exe,
 flex.exe,
 and gawk.exe.
 One good place to get them is here 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://unxutils.sourceforge.net
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

If UnxUtils didn't work well,
 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
msys
\end_layout

\end_inset

msys (
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.mingw.org/wiki/msys
\end_layout

\end_inset

) or msys2
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
msys2
\end_layout

\end_inset

(
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

https://msys2.github.io
\end_layout

\end_inset

) can be an alternative.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Download the file UnxUtils
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
UnxUtils
\end_layout

\end_inset

.zip.
 Now you have to install the utilities and setup MSVC so it can locate the required programs.
 Here there are two alternatives (choose one!):
\end_layout

\begin_layout Enumerate
The easy way:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

a) Extract UnxUtils.zip to your C:
\backslash
 hard disk PRESERVING the original paths,
 otherwise bison won't work.
 (If you are using WinZip make certain that 'Use folder names' is selected)
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

b) Add 'C:
\backslash
user
\backslash
local
\backslash
wbin' to VC++ Directories / Executable Directories.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

(As a side effect,
 you get a bunch of Unix utilities that could be useful,
 such as diff and patch.)
\end_layout

\begin_layout Enumerate
A more compact way:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

This one avoids extracting a bunch of files you may not use,
 but requires some extra work:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

a) Create a directory were to put the tools needed,
 or use a directory already present.
 Say for example 'C:
\backslash
util'.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

b) Extract 'bison.exe',
 'bison.hairy',
 'bison.simple',
 'flex.exe',
 and gawk.exe to such directory WITHOUT preserving the original paths.
 (If you are using WinZip make certain that 'Use folder names' is not selected)
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

c) Rename bison.exe to '_bison.exe'.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

d) Create a batch file 'bison.bat' in 'C:
\backslash
util
\backslash
' and add these lines:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

set BISON_SIMPLE=C:
\backslash
util
\backslash
bison.simple 
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

set BISON_HAIRY=C:
\backslash
util
\backslash
bison.hairy
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

_bison %1 %2 %3 %4 %5 %6 %7 %8 %9
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Steps 'c' and 'd' are needed because bison requires by default that the files 'bison.simple' and 'bison.hairy' reside in some weird Unix directory,
 '/usr/local/share/' I think.
 So it is necessary to tell bison where those files are located if they are not in such directory.
 That is the function of the environment variables BISON_SIMPLE and BISON_HAIRY.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

e) Add 'C:
\backslash
util' to VC++ Directories / Executable Directories.
 Note that you can use any other path instead of 'C:
\backslash
util',
 even the path where the Visual C++ tools are,
 probably:
 'C:
\backslash
Program Files
\backslash
Microsoft Visual Studio
\backslash
Common
\backslash
Tools'.
 So you don't have to execute step 'e' :)
\end_layout

\begin_layout Standard
That is it.
 Open 'sdcc.sln' in Visual Studio,
 click 'build all',
 when it finishes copy the executables from sdcc
\backslash
bin_vc to sdcc
\backslash
bin,
 and you can compile using SDCC.
\end_layout

\begin_layout Subsection
Windows Install Using a ZIP Package
\end_layout

\begin_layout Enumerate
Download the binary zip package from 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sf.net/snap.php
\end_layout

\end_inset

 and unpack it using your favorite unpacking tool (gunzip,
 WinZip,
 etc).
 This should unpack to a group of sub-directories.
 An example directory structure after unpacking the mingw32 package is:
 C:
\backslash
sdcc
\backslash
bin for the executables,
 C:
\backslash
sdcc
\backslash
include and C:
\backslash
sdcc
\backslash
lib for the include and libraries.
\end_layout

\begin_layout Enumerate
Adjust your environment variable PATH to include the location of the bin directory or start sdcc using the full path.
\end_layout

\begin_layout Subsection
Windows Install Using the Setup Program
\begin_inset CommandInset label
LatexCommand label
name "subsec:Windows-Install"

\end_inset


\end_layout

\begin_layout Standard
Download the setup program 
\emph on
sdcc-x.y.z-setup.exe
\emph default
 for an official release from
\begin_inset Newline newline
\end_inset


\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/projects/sdcc/files/
\end_layout

\end_inset

 or a setup program for one of the snapshots 
\emph on
sdcc-yyyymmdd-xxxx-setup.exe
\emph default
 from 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/snap.php
\end_layout

\end_inset

 and execute it.
 A Windows typical installer will guide you through the installation process.
\end_layout

\begin_layout Subsection
VPATH
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
VPATH
\end_layout

\end_inset

 feature
\end_layout

\begin_layout Standard
SDCC supports the VPATH feature provided by configure and make.
 It allows to separate the source and build trees.
 Here's an example:
\end_layout

\begin_layout Standard

\family typewriter
cd ~
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

# cd $HOME
\end_layout

\begin_layout Standard

\family typewriter
tar -xjf sdcc-src-yyyymmdd-rrrr.tar.bz2
\begin_inset space ~
\end_inset

# extract source to directory sdcc
\end_layout

\begin_layout Standard

\family typewriter
mkdir sdcc.build
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

# put output in sdcc.build
\end_layout

\begin_layout Standard

\family typewriter
cd sdcc.build
\end_layout

\begin_layout Standard

\family typewriter
../sdcc/configure
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

# configure is doing all the magic!
\end_layout

\begin_layout Standard

\family typewriter
make
\end_layout

\begin_layout Standard
\noindent
That's it!
 
\series bold
configure
\series default
 will create the directory tree will all the necessary Makefiles in ~/sdcc.build.
 It automagically computes the variables srcdir,
 top_srcdir and top_buildir for each directory.
 After running 
\series bold
make
\series default
 the generated files will be in ~/sdcc.build,
 while the source files stay in ~/sdcc.
\begin_inset Newline newline
\end_inset

This is not only usefull for building different binaries,
 e.g.
 when cross compiling.
 It also gives you a much better overview in the source tree when all the generated files are not scattered between the source files.
 And the best thing is:
 if you want to change a file you can leave the original file untouched in the source directory.
 Simply copy it to the build directory,
 edit it,
 enter `make clean',
 `rm Makefile.dep' and `make'.
 
\series bold
make
\series default
 will do the rest for you!
\end_layout

\begin_layout Section
Building the Documentation
\end_layout

\begin_layout Standard
Add -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-enable-doc to the configure arguments to build the documentation together with all the other stuff.
 You will need several tools (\SpecialChar LyX
,
 \SpecialChar LaTeX
,
 \SpecialChar LaTeX
2HTML,
 pdflatex,
 dvipdf,
 dvips and makeindex) to get the job done.
 Another possibility is to change to the doc directory and to type 
\family sans
\series bold

\begin_inset Quotes srd
\end_inset

make
\begin_inset Quotes srd
\end_inset


\family default
\series default
 there.
 You're invited to make changes and additions to this manual (sdcc/doc/sdccman.lyx).
 Using \SpecialChar LyX
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.lyx.org
\end_layout

\end_inset

 as editor is straightforward.
 Prebuilt documentation is available from 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/snap.php
\end_layout

\end_inset

.
\end_layout

\begin_layout Section
Reading the Documentation
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Documentation
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Currently,
 reading the document in PDF format is recommended,
 as for unknown reason the hyperlinks are working there whereas in the HTML version they are not
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
If you should know why please drop us a note
\end_layout

\end_inset

.
\begin_inset Newline newline
\end_inset

You'll find the PDF version
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PDF version of this document
\end_layout

\end_inset

 at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/doc/sdccman.pdf
\end_layout

\end_inset

.
\begin_inset Newline newline
\end_inset

This documentation is in some aspects different from a commercial documentation:
 
\end_layout

\begin_layout Itemize
It tries to document SDCC for several processor architectures in one document (commercially these probably would be separate documents/products).
 This document
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Status of documentation
\end_layout

\end_inset

 currently matches SDCC for mcs51 and DS390 best and does give too few information about f.e.
 Z80,
 PIC14,
 PIC16 and HC08.
\end_layout

\begin_layout Itemize
There are many references pointing away from this documentation.
 Don't let this distract you.
 If there f.e.
 was a reference like 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.opencores.org
\end_layout

\end_inset

 together with a statement 
\begin_inset Quotes sld
\end_inset

some processors which are targeted by SDCC can be implemented in a 
\emph on
f
\emph default
ield 
\emph on
p
\emph default
rogrammable 
\emph on
g
\emph default
ate 
\emph on
a
\emph default
rray
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
FPGA (field programmable gate array)
\end_layout

\end_inset


\begin_inset Quotes srd
\end_inset

 or 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/projects/fpgac/
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
FpgaC ((subset of) C to FPGA compiler)
\end_layout

\end_inset

 
\begin_inset Quotes sld
\end_inset

have you ever heard of an open source compiler that compiles a subset of C for an FPGA?
\begin_inset Quotes srd
\end_inset

 we expect you to have a quick look there and come back.
 If you read this you are on the right track.
\end_layout

\begin_layout Itemize
Some sections attribute more space to problems,
 restrictions and warnings than to the solution.
\end_layout

\begin_layout Itemize
The installation section and the section about the debugger is intimidating.
\end_layout

\begin_layout Itemize
There are still lots of typos and there are more different writing styles than pictures.
\end_layout

\begin_layout Section
Testing the SDCC Compiler
\begin_inset CommandInset label
LatexCommand label
name "sec:Testing-the-SDCC"

\end_inset


\end_layout

\begin_layout Standard
The first thing you should do after installing your SDCC compiler is to see if it runs.
 Type 
\family sans
\series bold
"sdcc -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-version"
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
version
\end_layout

\end_inset


\family default
\series default
 at the prompt,
 and the program should run and output its version like:
 
\begin_inset Newline newline
\end_inset


\family typewriter
SDCC :
 mcs51/z80/z180/r2k/r2ka/r3ka/sm83/tlcs90/ez80_z80/z80n/r800/ds390/pic16/pic14/TININative/ds400/hc08/s08/stm8/pdk13/pdk14/pdk15/mos6502/mos65c02 4.4.0 #14546 (Linux)
\end_layout

\begin_layout Standard
If it doesn't run,
 or gives a message about not finding sdcc program,
 then you need to check over your installation.
 Make sure that the sdcc bin directory is in your executable search path defined by the PATH environment setting (
\series medium
see
\series default
 section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Install-Trouble-shooting"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset


\series medium
Install trouble-shooting for suggestions
\series default
).
 Make sure that the sdcc program is in the bin folder,
 if not perhaps something did not install correctly.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\series medium
SDCC
\series default
 is commonly installed as described in section 
\begin_inset Quotes sld
\end_inset

Install and search paths
\begin_inset Quotes srd
\end_inset

.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\series medium
Make sure the compiler works on a very simple example.
 Type in the following test.c program using your favorite
\series default
 ASCII 
\series medium
editor:
\end_layout

\begin_layout Verse

\family typewriter
char test;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void main(void) {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

test=0;
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard

\series medium
Compile this using the following command:

\series default
 
\family sans
\series bold
"sdcc -c test.c".

\family default
\series default
 
\series medium
If all goes well,
 the compiler will generate a test.asm and test.rel file.
 Congratulations,
 you've just compiled your first program with SDCC.
 We used the -c option to tell SDCC not to link the generated code,
 just to keep things simple for this step.
\series default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\series medium
The next step is to try it with the linker.
 Type in
\series default
 
\family sans
\series bold
"sdcc test.c
\family default
\series default
"
\series medium
.
 If all goes well the compiler will link with the libraries and produce a test.ihx output file.
 If this step fails
\series default
 
\series medium
(no test.ihx,
 and the linker generates warnings),
 then the problem is most likely that
\series default
 SDCC 
\series medium
cannot find the
\series default
 /
\series medium
usr/local/share/sdcc/lib directory
\series default
 
\series medium
(see
\series default
 section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Install-Trouble-shooting"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset


\series medium
Install trouble-shooting for suggestions).
\series default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\series medium
The final test is to ensure
\series default
 SDCC 
\series medium
can use the
\series default
 standard 
\series medium
header files and libraries.
 Edit test.c and change it to the following:
\end_layout

\begin_layout Verse

\family typewriter
#include <string.h>
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

char str1[10];
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void main(void) {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

strcpy(str1,
 "testing");
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard

\series medium
Compile this by typing
\series default
 
\family sans
\series bold
"sdcc test.c"
\family default
\series medium
.
 This should generate a test.ihx output file,
 and it should give no warnings such as not finding the string.h file.
 If it cannot find the string.h file,
 then the problem is that
\series default
 SDCC 
\series medium
cannot find the /usr/local/share/sdcc/include directory
\series default
 
\series medium
(see the
\series default
 section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Install-Trouble-shooting"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset


\series medium
Install trouble-shooting section for suggestions).

\series default
 Use option 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-print-search-dirs
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-print-search-dirs
\end_layout

\end_inset

 to find exactly where SDCC is looking for the include and lib files.
\end_layout

\begin_layout Section
Install Trouble-shooting
\begin_inset CommandInset label
LatexCommand label
name "subsec:Install-Trouble-shooting"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Install trouble-shooting
\end_layout

\end_inset


\end_layout

\begin_layout Subsection
If SDCC does not build correctly
\end_layout

\begin_layout Standard
A thing to try is starting from scratch by unpacking the .tgz source package again in an empty directory.
 Configure it like:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
./configure 2>&1 | tee configure.log
\family default
\series default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

and build it like:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
make 2>&1 | tee make.log
\family default
\series default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

If anything goes wrong,
 you can review the log files to locate the problem.
 Or a relevant part of this can be attached to an email that could be helpful when requesting help from the mailing list.
\end_layout

\begin_layout Subsection
What the 
\begin_inset Quotes sld
\end_inset

./configure
\begin_inset Quotes srd
\end_inset

 does
\end_layout

\begin_layout Standard
The 
\begin_inset Quotes sld
\end_inset

./configure
\begin_inset Quotes srd
\end_inset

 command is a script that analyzes your system and performs some configuration to ensure the source package compiles on your system.
 It will take a few minutes to run,
 and will compile a few tests to determine what compiler features are installed.
\end_layout

\begin_layout Subsection
What the 
\begin_inset Quotes sld
\end_inset

make
\begin_inset Quotes srd
\end_inset

 does
\end_layout

\begin_layout Standard
This runs the GNU make tool,
 which automatically compiles all the source packages into the final installed binary executables.
\end_layout

\begin_layout Subsection
What the 
\begin_inset Quotes sld
\end_inset

make install
\begin_inset Quotes erd
\end_inset

 command does.
\end_layout

\begin_layout Standard
This will install the compiler,
 other executables libraries and include files into the appropriate directories.
 See sections 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Install-paths"
nolink "false"

\end_inset

,
\begin_inset space ~
\end_inset


\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Search-Paths"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset

about install and search paths.
\begin_inset Newline newline
\end_inset

On most systems you will need super-user privileges to do this.
\end_layout

\begin_layout Section
Components of SDCC
\end_layout

\begin_layout Standard
SDCC is not just a compiler,
 but a collection of tools by various developers.
 These include linkers,
 assemblers,
 simulators and other components.
 Here is a summary of some of the components.
 Note that the included simulator and assembler have separate documentation which you can find in the source package in their respective directories.
 As SDCC grows to include support for other processors,
 other packages from various developers are included and may have their own sets of documentation.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

You might want to look at the files which are installed in <installdir>.
 At the time of this writing,
 we find the following programs,
 among others,
 for gcc-builds:
\begin_inset Newline newline
\end_inset

 
\begin_inset Newline newline
\end_inset

In <installdir>/bin:
\end_layout

\begin_layout Itemize
sdcc - The compiler.
\end_layout

\begin_layout Itemize
sdcpp - The C preprocessor.
\end_layout

\begin_layout Itemize
sdas8051 - The assembler for 8051 type processors.
\end_layout

\begin_layout Itemize
sdas390 - The assembler for DS80C390 processor.
\end_layout

\begin_layout Itemize
sdasz80
\series bold
,

\series default
 sdasgb - The Z80 and GameBoy Z80 assemblers.
\end_layout

\begin_layout Itemize
sdas6808 - The 6808 assembler.
\end_layout

\begin_layout Itemize
sdasstm8 - The STM8 assembler.
\end_layout

\begin_layout Itemize
sdld -The linker for 8051 and STM8 type processors.
\end_layout

\begin_layout Itemize
sdldz80
\series bold
,

\series default
 sdldgb - The Z80 and GameBoy Z80 linkers.
\end_layout

\begin_layout Itemize
sdld6808 - The 6808 linker.
\end_layout

\begin_layout Itemize
ucsim_51,
 s51 - The ucSim 8051 simulator.
\end_layout

\begin_layout Itemize
ucsim_m68hc08 - The ucSim 6808 simulator.
\end_layout

\begin_layout Itemize
ucsim_stm8 - The ucSim STM8 simulator.
\end_layout

\begin_layout Itemize
ucsim_z80 - The ucSim Z80 simulator.
\end_layout

\begin_layout Itemize
sdcdb - The source debugger.
\end_layout

\begin_layout Itemize
sdar,
 sdranlib,
 sdnm,
 sdobjcopy - The sdcc archive managing and indexing utilites.
\end_layout

\begin_layout Itemize
packihx - A tool to pack (compress) Intel hex files.
\end_layout

\begin_layout Itemize
makebin - A tool to convert Intel Hex file to a binary and GameBoy binary image file format.
\end_layout

\begin_layout Standard
In <installdir>/share/sdcc/include
\end_layout

\begin_layout Itemize
the include files
\end_layout

\begin_layout Standard
In <installdir>/share/sdcc/non-free/include
\end_layout

\begin_layout Itemize
the non-free include files
\end_layout

\begin_layout Standard
In <installdir>/share/sdcc/lib
\end_layout

\begin_layout Itemize
the src and target subdirectories with the precompiled relocatables.
\end_layout

\begin_layout Standard
In <installdir>/share/sdcc/non-free/lib
\end_layout

\begin_layout Itemize
the src and target subdirectories with the non-free precompiled relocatables.
\end_layout

\begin_layout Standard
In <installdir>/share/sdcc/doc
\end_layout

\begin_layout Itemize
the documentation
\end_layout

\begin_layout Subsection
sdcc - The Compiler
\end_layout

\begin_layout Standard
This is the actual compiler,
 it in turn uses the C-preprocessor and invokes the assembler and linkage editor.
\end_layout

\begin_layout Subsection
sdcpp - The C-Preprocessor
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Preprocessor
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The preprocessor
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sdcpp (preprocessor)
\end_layout

\end_inset

 is a modified version of the GNU cpp
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
cpp|see
\begin_inset ERT
status collapsed

\begin_layout Plain Layout

{
\end_layout

\end_inset

sdcpp
\begin_inset ERT
status collapsed

\begin_layout Plain Layout

}
\end_layout

\end_inset


\end_layout

\end_inset

 preprocessor 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://gcc.gnu.org/
\end_layout

\end_inset

.
 The C preprocessor is used to pull in #include sources,
 process #ifdef statements,
 #defines and so on.
\end_layout

\begin_layout Subsection
sdas,
 sdld - The Assemblers and Linkage Editors
\end_layout

\begin_layout Standard
This is a set of retargettable assemblers and linkage editors,
 which was developed by Alan Baldwin.
 John Hartman created the version for 8051,
 and I (Sandeep) have made some enhancements and bug fixes for it to work properly with SDCC.
 
\end_layout

\begin_layout Standard
SDCC used an about 1998 branch of asxxxx version 2.0 which unfortunately is not compatible with the more advanced (f.e.
 macros,
 more targets) ASxxxx Cross Assemblers nowadays available from Alan Baldwin 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

https://shop-pdp.net/
\end_layout

\end_inset

.
 In 2009 Alan made his ASxxxx Cross Assemblers version 5.0 available under the GPL license (GPLv3 or later),
 so a reunion is now a work in progress.
 Thanks Alan!
\end_layout

\begin_layout Subsection
ucsim_51,
 ucsim_z80,
 ucsim_stm8 etc.
 - The Simulators
\end_layout

\begin_layout Standard
ucsim_51 (or s51)
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
s51 (simulator)
\end_layout

\end_inset

,
 ucsim_z80
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sz80 (simulator)
\end_layout

\end_inset

 ucsim_m68hc08
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
shc08 (simulator)
\end_layout

\end_inset

 and ucsim_stm8 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sstm8 (simulator)
\end_layout

\end_inset

,
 as well as similarly named programs provided with SDCC,
 are free open source simulators developed by Daniel Drotos.
 The simulators are built as part of the build process.
 For more information visit Daniel's web site at:
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://mazsola.iit.uni-miskolc.hu/~drdani/embedded/s51
\end_layout

\end_inset

.
 It currently supports the core mcs51,
 the Dallas DS80C390,
 the Phillips XA51 family,
 the Z80,
 6808 the STM8 and various others.
\end_layout

\begin_layout Subsection
sdcdb - Source Level Debugger
\end_layout

\begin_layout Standard
SDCDB
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCDB (debugger)
\end_layout

\end_inset

 is the companion source level debugger.
 More about SDCDB in section 
\begin_inset CommandInset ref
LatexCommand ref
reference "cha:Debugging-with-SDCDB"
nolink "false"

\end_inset

.
 The current version of the debugger uses Daniel's Simulator S51
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
s51 (simulator)
\end_layout

\end_inset

,
 but can be easily changed to use other simulators.
\end_layout

\begin_layout Chapter
Using SDCC
\end_layout

\begin_layout Section
Standard-Compliance
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Standard-compliance
\end_layout

\end_inset


\begin_inset CommandInset label
LatexCommand label
name "subsec:Standard-Compliance"

\end_inset


\end_layout

\begin_layout Standard
SDCC aims to be a conforming freestanding implementation of the C programming language.
 The latest publicly available version of the standard 
\emph on
ISO/IEC 9899 - Programming languages - C
\emph default
 should be available at:
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

https://www.open-std.org/jtc1/sc22/wg14/www/projects#9899
\end_layout

\end_inset

.
\end_layout

\begin_layout Subsection
ISO C90 and ANSI C89
\end_layout

\begin_layout Standard
Use 
\series bold

\begin_inset Flex Code
status open

\begin_layout Plain Layout

\series bold
--std-c90
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-std-c90
\end_layout

\end_inset


\series default
 to compile in this mode.
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Subsubsection*
Deviations from standard compliance
\end_layout

\begin_layout Itemize
initialization of structure arrays must be fully braced.
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_deeper
\begin_layout Verse

\family typewriter
struct s { char x } a[] = {1,
 2};
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* invalid in SDCC */
\begin_inset Newline newline
\end_inset

struct s { char x } a[] = {{1},
 {2}};
 /* OK */
\end_layout

\end_deeper
\begin_layout Itemize
\begin_inset Flex Code
status open

\begin_layout Plain Layout
float
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Floating point support
\end_layout

\end_inset

 is substituted for (
\begin_inset Flex Code
status open

\begin_layout Plain Layout
long
\end_layout

\end_inset

) 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
double
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
double (not supported)
\end_layout

\end_inset

 and a warning is emitted.
\end_layout

\begin_layout Itemize
K&R style
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
K
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
&
\end_layout

\end_inset

R style
\end_layout

\end_inset

 functions are syntactically supported,
 but with the semantics of ISO style functions.
\end_layout

\begin_layout Subsubsection*
Features missing in some ports
\end_layout

\begin_layout Itemize
pic14,
 pic16:
 structures
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
struct
\end_layout

\end_inset

 and unions
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
union
\end_layout

\end_inset

 cannot be passed as function parameters
\end_layout

\begin_layout Itemize
hc08,
 s08,
 mos6502,
 pic14,
 pic16:
 they cannot be a return value
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
return value
\end_layout

\end_inset

 from a function,
 e.g.:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_deeper
\begin_layout Verse

\family typewriter
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\begin_inset Newline newline
\end_inset


\series bold
struct
\family default
\series default
 
\family typewriter
s foo1 (
\series bold
struct
\family default
\series default
 
\family typewriter
s parms) /* unsupported in these SDCC ports */
\begin_inset Newline newline
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{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
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\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

struct s rets;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
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...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return rets;
 /* unsupported in these SDCC ports */
\begin_inset Newline newline
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\end_deeper
\begin_layout Itemize
mcs51,
 ds390,
 hc08,
 s08,
 pdk13,
 pdk14,
 pdk15 and mos6502 ports:
 functions are not reentrant unless explicitly declared as such or 
\series bold

\begin_inset Flex Code
status open

\begin_layout Plain Layout

\series bold
--
\series default
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\end_layout

\end_inset


\series default
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\begin_layout Subsection
ISO C95
\end_layout

\begin_layout Standard
Use 
\series bold

\begin_inset Flex Code
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\begin_layout Plain Layout

\series bold
--std-c95
\end_layout

\end_inset


\begin_inset Index idx
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-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

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-std-c95
\end_layout

\end_inset


\series default
 to compile in this mode.
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\begin_layout Subsubsection*
Implementation status
\end_layout

\begin_layout Standard
Except for the issues mentioned in the section above,
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\end_layout

\begin_layout Subsection
ISO C99
\end_layout

\begin_layout Standard
Use 
\series bold

\begin_inset Flex Code
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\begin_layout Plain Layout

\series bold
--std-c99
\end_layout

\end_inset


\begin_inset Index idx
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status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-std-c99
\end_layout

\end_inset


\series default
 to compile in this mode.
\end_layout

\begin_layout Subsubsection*
Deviations from standard compliance
\end_layout

\begin_layout Standard
In addition to what is mentioned in the section above,
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\end_layout

\begin_layout Itemize
Compound literals.
 
\end_layout

\begin_layout Itemize
Objects of variably-modified types.
\end_layout

\begin_layout Itemize
\begin_inset Flex Code
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ptrdiff_t
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 has 16 bits,
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\end_layout

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Features missing in some ports
\end_layout

\begin_layout Itemize
pic14:
 there is no support for 64 bit integer types.
 
\end_layout

\begin_layout Subsection
ISO C11 and ISO C17
\end_layout

\begin_layout Standard
Use 
\series bold

\begin_inset Flex Code
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\begin_layout Plain Layout

\series bold
--std-c11
\end_layout

\end_inset


\begin_inset Index idx
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status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-std-c11
\end_layout

\end_inset


\series default
 to compile in this mode.
\end_layout

\begin_layout Subsubsection*
Implementation status
\end_layout

\begin_layout Standard
Except for the issues mentioned in the section above,
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\end_layout

\begin_layout Subsection
ISO C23
\end_layout

\begin_layout Standard
Use 
\series bold

\begin_inset Flex Code
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\begin_layout Plain Layout

\series bold
--std-c23
\end_layout

\end_inset


\begin_inset Index idx
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status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-std-c23
\end_layout

\end_inset


\series default
 to compile in this mode.
\end_layout

\begin_layout Subsubsection*
Deviations from standard compliance
\end_layout

\begin_layout Itemize
initialization of structure arrays must be fully braced.
\begin_inset Separator latexpar
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\begin_deeper
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\family typewriter
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\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* invalid in SDCC */
\begin_inset Newline newline
\end_inset

struct s { char x } a[] = {{1},
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\begin_layout Itemize
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Floating point support
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\begin_layout Plain Layout
double (not supported)
\end_layout

\end_inset

 and a warning is emitted.
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\begin_layout Itemize
Compound literals are not supported.
\end_layout

\begin_layout Itemize
Support for attributes is slightly incomplete.
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\begin_layout Itemize
Checked integer arithmetic is not supported for (
\begin_inset Flex Code
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) 
\begin_inset Flex Code
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long long
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.
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\begin_layout Itemize
\begin_inset Flex Code
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\begin_layout Plain Layout
constexpr
\end_layout

\end_inset

 is not implemented.
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\begin_layout Subsubsection*
Features missing in some ports
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\begin_layout Itemize
pic14,
 pic16:
 structures
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\begin_layout Plain Layout
struct
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\begin_inset Index idx
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union
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 cannot be passed as function parameters
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hc08,
 s08,
 mos6502,
 pic14,
 pic16:
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\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
return value
\end_layout

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 from a function,
 e.g.:
\begin_inset Separator latexpar
\end_inset


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\begin_deeper
\begin_layout Verse

\family typewriter
struct s { ...
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\begin_inset Newline newline
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\series bold
struct
\family default
\series default
 
\family typewriter
s foo1 (
\series bold
struct
\family default
\series default
 
\family typewriter
s parms) /* unsupported in these SDCC ports */
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

struct s rets;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return rets;
 /* unsupported in these SDCC ports */
\begin_inset Newline newline
\end_inset

}
\end_layout

\end_deeper
\begin_layout Itemize
mcs51,
 ds390,
 hc08,
 s08,
 pdk13,
 pdk14,
 pdk15 and mos6502 ports:
 functions are not reentrant unless explicitly declared as such or 
\series bold

\begin_inset Flex Code
status open

\begin_layout Plain Layout

\series bold
--
\series default
stack-auto
\end_layout

\end_inset


\series default
 is specified.
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\begin_layout Itemize
pic14:
 there is no support for 64 bit integer types.
 
\end_layout

\begin_layout Itemize
pic14,
 pic16:
 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
_BitInt
\end_layout

\end_inset

 is not supported.
\end_layout

\begin_layout Subsection
ISO C2y preview
\end_layout

\begin_layout Standard
Use 
\series bold

\begin_inset Flex Code
status open

\begin_layout Plain Layout

\series bold
--std-c2y
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-std-c2y
\end_layout

\end_inset


\series default
 to compile in this mode.
\end_layout

\begin_layout Subsubsection*
Implementation status
\end_layout

\begin_layout Standard
In anticipation of the upcoming version of the language standard,
 C2y,
 SDCC supports the following prospective features:
\end_layout

\begin_layout Itemize
\begin_inset CommandInset href
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:
 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
_Generic
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\end_inset

 selection expression with a type operand
\end_layout

\begin_layout Itemize
\begin_inset CommandInset href
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:
 Case range expressions
\end_layout

\begin_layout Subsection
Embedded C
\end_layout

\begin_layout Standard
SDCC supports objects in named address spaces and to some degree pointers to such objects.
 The support for fixed-point math in SDCC is inconsistent with the standard.
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\end_layout

\begin_layout Subsection
Implementation-defined behavior
\end_layout

\begin_layout Subsubsection
Translation
\end_layout

\begin_layout Itemize
Diagnostics are output to stderr,
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 <diagnostic-description>
\end_layout

\begin_layout Itemize
Nonempty sequences of white-space are retained in translation phase 3.
\end_layout

\begin_layout Subsubsection
Environment
\end_layout

\begin_layout Itemize
See SDCC source (and your own code if you use a custom crt0 for a target that supports it) for any information on the environment.
\end_layout

\begin_layout Subsubsection
Identifiers
\end_layout

\begin_layout Itemize
See the compiler and assembler source for information on characters that may appear in identifiers and on the number of significant initial characters.
\end_layout

\begin_layout Subsubsection
Characters
\end_layout

\begin_layout Itemize
There are 8 bits in a byte.
\end_layout

\begin_layout Itemize
Values of members of the execution character set:
 TODO.
\end_layout

\begin_layout Itemize
Values of members of the execution character set for escape sequences:
 TODO.
\end_layout

\begin_layout Itemize
Value of char with something weird stored in it:
 TODO.
\end_layout

\begin_layout Itemize
unsigned char has the same range,
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\begin_inset Quotes sld
\end_inset

plain
\begin_inset Quotes srd
\end_inset

 char (unless -
\series bold

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series default
-fsigned-char
\series bold

\begin_inset Index idx
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pageformat default
status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-fsigned-char
\end_layout

\end_inset


\series default
 is used).
\end_layout

\begin_layout Itemize
See the SDCC source for further information on character sets.
\end_layout

\begin_layout Subsubsection
Integers
\end_layout

\begin_layout Itemize
There are no extended integer types.
\end_layout

\begin_layout Subsubsection
Floating point
\end_layout

\begin_layout Itemize
See the implementation (soft float library) for any information on floating point.
\end_layout

\begin_layout Subsubsection
Arrays and Pointers
\end_layout

\begin_layout Itemize
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\end_layout

\begin_layout Itemize
For the size of the result of subtracting two pointers to elements of the same array see the SDCC source code.
\end_layout

\begin_layout Subsubsection
Hints
\end_layout

\begin_layout Itemize
The extend to which suggestions made by register are effective depends on the target.
\end_layout

\begin_layout Itemize
SDCC will inline functions if and only if they are declared using inline and do not have variable arguments.
\end_layout

\begin_layout Subsubsection
Structures,
 unions,
 enumerations and bit-fields
\end_layout

\begin_layout Itemize
A plain int bit-field is treated as an unsigned int bit-field.
\end_layout

\begin_layout Itemize
There are no allowed bit-field types other than _Bool,
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 signed int,
 unsigned int and the bit-precise integer types.
\end_layout

\begin_layout Itemize
Atomic types are not permitted for bit-fields.
\end_layout

\begin_layout Itemize
If a bit-fields does not fit into the same byte as the previous bit-fields,
 it starts on the next byte.
\end_layout

\begin_layout Itemize
bit-fields are allocated in the same order as they appear in the source.
\end_layout

\begin_layout Itemize
Non-bit-field members of structures are aligned on byte boundaries (i.e.
 there are no padding bytes).
\end_layout

\begin_layout Itemize
For enumerations,
 the compatible type is the first from the following list that fits the constants:
 bool,
 unsigned char,
 signed char,
 unsigned int,
 signed int,
 unsigned long int,
 signed long int,
 unsigned long long int,
 signed long long int.
\end_layout

\begin_layout Subsubsection
Qualifiers
\end_layout

\begin_layout Itemize
SDCC shall preserve all volatile reads and writes,
 but does not guarantee them to be atomic (except for atomic types and volatile sig_atomic_t).
\end_layout

\begin_layout Subsubsection
Preprocessing directives
\end_layout

\begin_layout Itemize
See the preprocessor source for information on preprocessing directives.
\end_layout

\begin_layout Subsubsection
Library functions
\end_layout

\begin_layout Itemize
See the respective library headers for the library functions available.
\end_layout

\begin_layout Itemize
See assert.h and library source for the format of the diagnostic printed by the assert macro.
\end_layout

\begin_layout Itemize
There is no fegetexceptflag function.
\end_layout

\begin_layout Itemize
There is no feraiseexcept function.
\end_layout

\begin_layout Itemize
There is no setlocale function.
\end_layout

\begin_layout Itemize
There is no FLT_EVAL_METHOD macro.
\end_layout

\begin_layout Itemize
There is no DEC_EVAL_METHOD macro.
\end_layout

\begin_layout Itemize
There are no non-required domain errors for mathematics functions.
\end_layout

\begin_layout Itemize
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\end_layout

\begin_layout Itemize
See library headers for the null-pointer constant to which NULL expands.
\end_layout

\begin_layout Itemize
See library headers and source for anything else about the library.
\end_layout

\begin_layout Subsubsection
Architecture
\end_layout

\begin_layout Itemize
See the respective library headers for the values or expressions for macros specified in float.h,
 limits.h,
 stdint.h.
\end_layout

\begin_layout Itemize
Multithreading is not supported.
\end_layout

\begin_layout Itemize
The number of bytes in any object is the minimum allowed (except for some padding bits on bit-fields),
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\end_layout

\begin_layout Itemize
No extended alignments are supported.
\end_layout

\begin_layout Itemize
There are no valid alignments other than those returned by _Alignof.
\end_layout

\begin_layout Itemize
sizeof always returns the smallest value allowed assuming an 8-bit char.
 _Alignof always returns 0.
\end_layout

\begin_layout Section
Compiling
\end_layout

\begin_layout Subsection
Single Source File Projects
\end_layout

\begin_layout Standard
For single source file 8051 projects the process is very simple.
 Compile your programs with the following command 
\family sans
\series bold
"sdcc sourcefile.c".

\family default
\series default
 This will compile,
 assemble and link your source file.
 Output files are as follows:
\end_layout

\begin_layout Itemize
sourcefile.asm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.asm
\end_layout

\end_inset

 - Assembler source
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status collapsed

\begin_layout Plain Layout
Assembler source
\end_layout

\end_inset

 file created by the compiler
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\begin_layout Itemize
sourcefile.lst
\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
<file>.lst
\end_layout

\end_inset

 - Assembler listing
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Assembler listing
\end_layout

\end_inset

 file created by the Assembler
\end_layout

\begin_layout Itemize
sourcefile.rst
\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
<file>.rst
\end_layout

\end_inset

 - Assembler listing
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Assembler listing
\end_layout

\end_inset

 file updated with linkedit information,
 created by linkage editor
\end_layout

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sourcefile.sym
\begin_inset Index idx
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pageformat default
status collapsed

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<file>.sym
\end_layout

\end_inset

 - symbol listing
\begin_inset Index idx
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pageformat default
status collapsed

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\end_layout

\end_inset

 for the sourcefile,
 created by the assembler
\end_layout

\begin_layout Itemize
sourcefile.rel
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pageformat default
status collapsed

\begin_layout Plain Layout
<file>.rel
\end_layout

\end_inset

 - Object file
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pageformat default
status collapsed

\begin_layout Plain Layout
Object file
\end_layout

\end_inset

 created by the assembler,
 input to Linkage editor
\end_layout

\begin_layout Itemize
sourcefile.map
\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
<file>.map
\end_layout

\end_inset

 - The memory map
\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
Memory map
\end_layout

\end_inset

 for the load module,
 created by the Linker
\end_layout

\begin_layout Itemize
sourcefile.mem
\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
<file>.mem
\end_layout

\end_inset

 - A file with a summary of the memory usage
\end_layout

\begin_layout Itemize
sourcefile.ihx
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.ihx
\end_layout

\end_inset

 - The load module in Intel hex format
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Intel hex format
\end_layout

\end_inset

 (you can select the Motorola S19 format
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Motorola S19 format
\end_layout

\end_inset

 with -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-out-fmt-s19
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-out-fmt-s19
\end_layout

\end_inset

.
 If you need another format you might want to use 
\family sans
\shape italic
objdump
\family default
\shape default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
objdump (tool)
\end_layout

\end_inset

 or 
\family sans
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srecord
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\shape default

\begin_inset Index idx
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\begin_layout Plain Layout
srecord (bin,
 hex,
 ...
 tool)
\end_layout

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\begin_inset Note Note
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hyperlinks needed
\end_layout

\end_inset

 - see also section 
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reference "subsec:Postprocessing-the-Intel"
nolink "false"

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).
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\begin_inset Index idx
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srecord (bin,
 hex,
 ...
 tool)
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
sourcefile.adb
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.adb
\end_layout

\end_inset

 - An intermediate file containing debug information needed to create the .cdb file (with -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug
\end_layout

\end_inset

) 
\end_layout

\begin_layout Itemize
sourcefile.cdb
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.cdb
\end_layout

\end_inset

 - An optional file (with -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug) containing debug information.
 The format is documented in cdbfileformat.pdf
\end_layout

\begin_layout Itemize
sourcefile.omf
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.omf
\end_layout

\end_inset

 - An optional AOMF or AOMF51
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
AOMF,
 AOMF51
\end_layout

\end_inset

 
\begin_inset CommandInset label
LatexCommand label
name "OMF file"

\end_inset

file containing debug information (generated with option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug).
 The (Intel) 
\emph on
a
\emph default
bsolute 
\emph on
o
\emph default
bject 
\emph on
m
\emph default
odule 
\emph on
f
\emph default
ormat is a subformat of the OMF51 format and is commonly used by third party tools (debuggers
\begin_inset Index idx
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pageformat default
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\begin_layout Plain Layout
Debugger
\end_layout

\end_inset

,
 simulators,
 emulators).
\end_layout

\begin_layout Itemize
sourcefile.dump*
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.dump*
\end_layout

\end_inset

 - Dump file to debug the compiler it self (generated with option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-dumpall) (see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Intermediate-Dump-Options"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset

 and section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:The-anatomy-of"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset


\begin_inset Quotes sld
\end_inset

Anatomy of the compiler
\begin_inset Quotes srd
\end_inset

).
\end_layout

\begin_layout Subsection
Postprocessing the Intel Hex
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Intel hex format
\end_layout

\end_inset

 file
\begin_inset CommandInset label
LatexCommand label
name "subsec:Postprocessing-the-Intel"

\end_inset


\end_layout

\begin_layout Standard
In most cases this won't be needed but the Intel Hex file
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.ihx
\end_layout

\end_inset

 which is generated by SDCC might include lines of varying length and the addresses within the file are not guaranteed to be strictly ascending.
 If your toolchain or a bootloader does not like this you can use the tool 
\family typewriter
packihx
\family default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
packihx (tool)
\end_layout

\end_inset

 which is part of the SDCC distribution:
 
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

 
\family sans
\series bold
packihx sourcefile.ihx >sourcefile.hex
\family default
\series default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The separately available 
\emph on
srecord
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
srecord (bin,
 hex,
 ...
 tool)
\end_layout

\end_inset

 package additionally allows to set undefined locations to a predefined value,
 to insert checksums
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
checksum
\end_layout

\end_inset

 of various flavours (crc,
 add,
 xor) and to perform other manipulations (convert,
 split,
 crop,
 offset,
 ...).
 
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
srec_cat
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sourcefile.ihx -intel
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

-o sourcefile.hex -intel
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family default
\series default
An example for a more complex command line
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
the command backfills
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
backfill unused memory
\end_layout

\end_inset

 unused memory with 0x12 and the overall 16 bit sum of the complete 64 kByte block is zero.
 If the program counter on an mcs51 runs wild the backfill pattern 0x12 will be interpreted as an 
\family typewriter
lcall
\family default
 to address 
\family typewriter
0x1212
\family default
 (where an emergency routine could sit).
\end_layout

\end_inset

 could look like:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
\size footnotesize
srec_cat
\begin_inset space ~
\end_inset

sourcefile.ihx -intel
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

-fill 0x12 0x0000 0xfffe
\begin_inset space ~
\end_inset

-little-endian-checksum-negative 0xfffe 0x02 0x02
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

-o sourcefile.hex -intel
\size default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family default
\series default
The srecord package is available at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/projects/srecord/
\end_layout

\end_inset

.
\end_layout

\begin_layout Subsection
Projects with Multiple Source Files
\end_layout

\begin_layout Standard
SDCC can compile only ONE file at a time.
 Let us for example assume that you have a project containing the following files:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

foo1.c (contains some functions)
\begin_inset Newline newline
\end_inset

foo2.c (contains some more functions)
\begin_inset Newline newline
\end_inset

foomain.c (contains more functions and the function main)
\begin_inset Newline newline
\end_inset


\size footnotesize

\begin_inset Newline newline
\end_inset


\size default
The first two files will need to be compiled separately with the commands:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
sdcc
\begin_inset space ~
\end_inset

-c
\begin_inset space ~
\end_inset

foo1.c
\family default
\series default
\size footnotesize

\begin_inset Newline newline
\end_inset


\family sans
\series bold
\size default
sdcc
\begin_inset space ~
\end_inset

-c
\begin_inset space ~
\end_inset

foo2.c
\family default
\series default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Then compile the source file containing the 
\emph on
main()
\emph default
 function and link
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Linker
\end_layout

\end_inset

 the files together with the following command:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
sdcc
\begin_inset space ~
\end_inset

foomain.c
\begin_inset space ~
\end_inset

foo1.rel
\begin_inset space ~
\end_inset

foo2.rel
\family default
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.rel
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Note that in this case,
 
\begin_inset Flex Strong
status open

\begin_layout Plain Layout
the source file being compiled is always linked in first
\end_layout

\end_inset

,
 regardless of its position in the command line.
 This can be problematic when a custom CRT is supplied as object file.
 As an alternative to the above,
 
\emph on
foomain.c
\emph default
 can be compiled separately,
 and the resulting object file can then be linked with the other object files using a separate command:
\family sans
\series bold

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

sdcc
\begin_inset space ~
\end_inset

-c
\begin_inset space ~
\end_inset

foomain.c
\begin_inset Newline newline
\end_inset

sdcc foomain.rel foo1.rel foo2.rel
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family default
\series default

\begin_inset Flex Strong
status open

\begin_layout Plain Layout
The file containing the 
\emph on
main()
\emph default
 function must be the first file specified in the command line
\end_layout

\end_inset

,
 since the linkage editor processes object files in the order they are presented to it.
 The linker is invoked from SDCC using a script file with extension .lnk
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.lnk
\end_layout

\end_inset

.
 You can view this file to troubleshoot linking problems such as those arising from missing libraries.
\end_layout

\begin_layout Subsection
Projects with Additional Libraries
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Libraries
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Some reusable routines may be compiled into a library,
 see the documentation for the assembler and linkage editor (which are in <installdir>/share/sdcc/doc) for how to create a 
\emph on
.lib
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.lib
\end_layout

\end_inset


\emph default
 library file.
 Section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Using-sdar-to"
plural "false"
caps "false"
noprefix "false"
nolink "false"

\end_inset

 below contains a minimal example.
 Libraries created in this manner can be included in the command line.
 Make sure you include the -L <library-path> option to tell the linker where to look for these files if they are not in the current directory.
 Here is an example,
 assuming you have the source file 
\emph on
foomain.c
\emph default
 and a library 
\emph on
foolib.lib
\emph default
 in the directory 
\emph on
mylib
\emph default
 (if that is not the same as your current project):
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
sdcc foomain.c foolib.lib -L mylib
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family default
\series default
Note here that 
\emph on
mylib
\emph default
 must be an absolute path name.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The most efficient way to use libraries is to keep separate modules in separate source files.
 The lib file now should name all the modules.rel
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.rel
\end_layout

\end_inset

 files.
 For an example see the standard library file 
\emph on
libsdcc.lib
\emph default
 in the directory <installdir>/share/lib/small.
\end_layout

\begin_layout Subsection
Using sdar to Create and Manage Libraries
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sdar
\end_layout

\end_inset


\begin_inset CommandInset label
LatexCommand label
name "subsec:Using-sdar-to"

\end_inset


\end_layout

\begin_layout Standard
Support for sdar format libraries was introduced in SDCC 2.9.0.
\series bold

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\series default
Both the GNU and BSD ar format variants are supported by sdld linkers.
\series bold

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\series default
To create a library containing sdas object files,
 you should use the following sequence:
\series bold

\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard

\family sans
\series bold
sdar -rc <library name>.lib <list of .rel files>
\end_layout

\begin_layout Section
Command Line Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Command Line Options
\end_layout

\end_inset


\begin_inset CommandInset label
LatexCommand label
name "sec:Command-Line-Options"

\end_inset


\end_layout

\begin_layout Subsection
Processor Selection Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options processor selection
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Processor selection options
\end_layout

\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mmcs51
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mmcs51
\end_layout

\end_inset


\series default
 Generate code for the Intel MCS51
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
MCS51
\end_layout

\end_inset

 family of processors.
 This is the default processor target.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mds390
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mds390
\end_layout

\end_inset


\series default
 Generate code for the Dallas DS80C390
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS80C390
\end_layout

\end_inset

 processor.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mds400
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mds400
\end_layout

\end_inset


\series default
 Generate code for the Dallas DS80C400
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS80C400
\end_layout

\end_inset

 processor.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mhc08
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mhc08
\end_layout

\end_inset


\series default
 Generate code for the Freescale/Motorola HC08 (aka 68HC08) 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
HC08
\end_layout

\end_inset

 family of processors.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-ms08
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-ms08
\end_layout

\end_inset


\series default
 Generate code for the Freescale/Motorola S08 (aka 68HCS08,
 HCS08,
 CS08) 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
S08
\end_layout

\end_inset

 family of processors.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mz80
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mz80
\end_layout

\end_inset


\series default
 Generate code for the Zilog Z80
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80
\end_layout

\end_inset

 family of processors.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mz180
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mz180
\end_layout

\end_inset


\series default
 Generate code for the Zilog Z180
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z180
\end_layout

\end_inset

 family of processors.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mr2k
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mr2k
\end_layout

\end_inset


\series default
 Generate code for the Rabbit 2000 / Rabbit 3000 family of processors.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mr3ka
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mr3ka
\end_layout

\end_inset


\series default
 Generate code for the Rabbit 3000A family of processors.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-msm83
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-msm83
\end_layout

\end_inset


\series default
 Generate code for the Sharp SM83
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
sm83 (GameBoy Z80)
\end_layout

\end_inset

 processor.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mtlcs90
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-mtlcs90
\end_layout

\end_inset


\series default
 Generate code for the Toshiba TLCS-90 processor.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mez80_z80
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-mez80_z80
\end_layout

\end_inset


\series default
 Generate code for the Zilog eZ80 processor in Z80 mode.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mstm8
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mstm8
\end_layout

\end_inset


\series default
 Generate code for the STMicroelectronics STM8 family of processors.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mpdk13
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-mpdk13
\end_layout

\end_inset


\series default
 Generate code for Padauk processors with 13 bit wide program memory.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mpdk14
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-mpdk14
\end_layout

\end_inset


\series default
 Generate code for Padauk processors with 14 bit wide program memory.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mpdk15
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-mpdk15
\end_layout

\end_inset


\series default
 Generate code for Padauk processors with 15 bit wide program memory.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mpic14
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mpic14
\end_layout

\end_inset


\series default
 Generate code for the Microchip PIC 14
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14
\end_layout

\end_inset

-bit processors (p16f84 and variants.
 In development,
 not complete).
\end_layout

\begin_layout Standard
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
p16f627 p16f628 p16f84 p16f873 p16f877?
\end_layout

\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mpic16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mpic16
\end_layout

\end_inset


\series default
 Generate code for the Microchip PIC 16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16
\end_layout

\end_inset

-bit processors (p18f452 and variants.
 In development,
 not complete).
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mmos6502
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mmos6502
\end_layout

\end_inset


\series default
 Generate code for the original MOS Technology NMOS 6502 processor and compatible derivatives including the 6510 and 8502.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-mmos65c02
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-mmos65c02
\end_layout

\end_inset


\series default
 Generate code for the CMOS Rockwell/WDC 65C02.
 
\end_layout

\begin_layout Standard
SDCC inspects the program name it was called with so the processor family can also be selected by renaming the sdcc binary (to f.e.
 z80-sdcc) or by calling SDCC from a suitable link.
 Option -m has higher priority than setting from program name.
\end_layout

\begin_layout Subsection
Preprocessor Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options preprocessor
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Preprocessor!Options
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sdcpp (preprocessor)
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC uses 
\shape italic
sdcpp
\shape default
,
 an adapted version of the GNU Compiler Collection
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
gcc (GNU Compiler Collection)
\end_layout

\end_inset

 preprocessor 
\emph on
cpp
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
cpp|see
\begin_inset ERT
status collapsed

\begin_layout Plain Layout

{
\end_layout

\end_inset

sdcpp
\begin_inset ERT
status collapsed

\begin_layout Plain Layout

}
\end_layout

\end_inset


\end_layout

\end_inset

 (
\emph on
gcc
\emph default
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://gcc.gnu.org/
\end_layout

\end_inset

).
 If you need more dedicated options than those listed below please refer to the GCC
\begin_inset space ~
\end_inset

CPP
\begin_inset space ~
\end_inset

Manual at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.gnu.org/software/gcc/onlinedocs/
\end_layout

\end_inset

.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-I<path>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-I<path>
\end_layout

\end_inset


\series default
 The additional location where the preprocessor will look for <..h> or 
\begin_inset Quotes eld
\end_inset

..h
\begin_inset Quotes erd
\end_inset

 files.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-D<macro[=value]>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-D<macro[=value]>
\end_layout

\end_inset


\series default
 Command line definition of macros.
 Passed to the preprocessor.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-M
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-M
\end_layout

\end_inset


\series default
 Tell the preprocessor to output a rule suitable for make describing the dependencies of each object file.
 For each source file,
 the preprocessor outputs one make-rule whose target is the object file name for that source file and whose dependencies are all the files `#include'd in it.
 This rule may be a single line or may be continued with `
\backslash
'-newline if it is long.
 The list of rules is printed on standard output instead of the preprocessed C program.
 `-M' implies `-E
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-E
\end_layout

\end_inset

'.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-C
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-C
\end_layout

\end_inset


\series default
 Tell the preprocessor not to discard comments.
 Used with the `-E' option.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-MM
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-MM
\end_layout

\end_inset


\series default
\size large
 
\size default
Like `-M' but the output mentions only the user header files included with `#include 
\begin_inset Quotes eld
\end_inset

file"'.
 System header files included with `#include <file>' are omitted.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-Aquestion(answer)
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-Aquestion(answer)
\end_layout

\end_inset


\series default
 Assert the answer answer for question,
 in case it is tested with a preprocessor conditional such as `#if #question(answer)'.
 `-A-' disables the standard assertions that normally describe the target machine.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-Umacro
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-Umacro
\end_layout

\end_inset


\series default
 Undefine macro macro.
 `-U' options are evaluated after all `-D' options,
 but before any `-include' and `-imacros' options.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-dM
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-dM
\end_layout

\end_inset


\series default
 Tell the preprocessor to output only a list of the macro definitions that are in effect at the end of preprocessing.
 Used with the `-E' option.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-dD
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-dD
\end_layout

\end_inset


\series default
 Tell the preprocessor to pass all macro definitions into the output,
 in their proper sequence in the rest of the output.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-dN
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-dN
\end_layout

\end_inset


\series default
\size large
 
\size default
Like `-dD' except that the macro arguments and contents are omitted.
 Only `#define name' is included in the output.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-Wp
\begin_inset space ~
\end_inset

preprocessorOption[,preprocessorOption]
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-Wp preprocessorOption[,preprocessorOption]
\end_layout

\end_inset

...
 Pass the preprocessorOption to the preprocessor 
\family typewriter
sdcpp
\family default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sdcpp (preprocessor)
\end_layout

\end_inset

.
 
\end_layout

\begin_layout Subsection
Optimization Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options optimization
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Optimization options
\end_layout

\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nogcse
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nogcse
\end_layout

\end_inset


\series default
 Will not do global common subexpression elimination,
 this option may be used when the compiler creates undesirably large stack/data spaces to store compiler temporaries (
\emph on
s
\emph default
pill 
\emph on
loc
\emph default
ations,
 sloc
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sloc (spill location)
\end_layout

\end_inset

).
 A warning message will be generated when this happens and the compiler will indicate the number of extra bytes it allocated.
 It is recommended that this option NOT be used,
 #pragma
\begin_inset space ~
\end_inset

nogcse
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma nogcse
\end_layout

\end_inset

 can be used to turn off global subexpression elimination
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Subexpression elimination
\end_layout

\end_inset

 for a given function only.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-noinvariant
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-noinvariant
\end_layout

\end_inset


\series default
 Will not do loop invariant optimizations,
 this may be turned off for reasons explained for the previous option.
 For more details of loop optimizations performed see Loop Invariants in section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Loop-Optimizations"
nolink "false"

\end_inset

.
 It is recommended that this option NOT be used,
 #pragma
\begin_inset space ~
\end_inset

noinvariant
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma noinvariant
\end_layout

\end_inset

 can be used to turn off invariant optimizations for a given function only.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-noinduction
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-noinduction
\end_layout

\end_inset


\series default
 Will not do loop induction optimizations,
 see section strength reduction for more details.
 It is recommended that this option is NOT used,
 #pragma
\begin_inset space ~
\end_inset

noinduction
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma noinduction
\end_layout

\end_inset

 can be used to turn off induction optimizations for a given function only.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-noloopreverse
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-noloopreverse
\end_layout

\end_inset


\series default
\size large
 
\size default
Will not do loop reversal 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Loop reversing
\end_layout

\end_inset

optimization.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\series bold
nolabelopt
\series default
 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nolabelopt 
\end_layout

\end_inset

Will not optimize labels (makes the dumpfiles more readable).
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-xinit-opt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-xinit-opt
\end_layout

\end_inset


\series default
 Will not memcpy initialized data from code space into xdata space.
 This saves a few bytes in code space if you don't have initialized data
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Variable initialization
\end_layout

\end_inset

.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nooverlay
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nooverlay
\end_layout

\end_inset


\series default
  The compiler will not overlay parameters and local variables of any function,
 see section Parameters and local variables for more details.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-peep
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-peep
\end_layout

\end_inset


\series default
 Disable peep-hole optimization with built-in rules.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-file
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-file
\end_layout

\end_inset


\begin_inset space ~
\end_inset

<filename> This option can be used to use additional rules to be used by the peep hole optimizer.
 See section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Peephole-Optimizer"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset

Peep Hole optimizations for details on how to write these rules.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-asm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-asm
\end_layout

\end_inset


\series default
 Pass the inline assembler code through the peep hole optimizer.
 This can cause unexpected changes to inline assembler code,
 please go through the peephole optimizer
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Peephole optimizer
\end_layout

\end_inset

 rules defined in the source file tree '<target>/peeph.def' before using this option.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-return
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-return
\end_layout

\end_inset


\series default
 Let the peep hole optimizer do return optimizations.
 This is the default without 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\series default
debug
\series bold

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug
\end_layout

\end_inset


\series default
.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-peep-return
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-peep-return
\end_layout

\end_inset


\series default
 Do not let the peep hole optimizer do return optimizations.
 This is the default with 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\series default
debug
\series bold

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug
\end_layout

\end_inset


\series default
.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-opt-code-speed
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-opt-code-speed
\end_layout

\end_inset


\series default
 The compiler will optimize code generation towards fast code,
 possibly at the expense of code size.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-opt-code-size
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-opt-code-size
\end_layout

\end_inset


\series default
 The compiler will optimize code generation towards compact code,
 possibly at the expense of code speed.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\series bold
fomit-frame-pointer
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-fomit-frame-pointer
\end_layout

\end_inset

 Frame pointer will be omitted when the function uses no local variables.
 On the z80-related ports this option will result in the frame pointer always being omitted.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\series bold
max-allocs-per-node
\series default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-max-allocs-per-node
\end_layout

\end_inset

 Setting this to a high value will result in increased compilation time (and increased memory use during compilation) and more optimized code being generated.
 Setting it to lower values speeds up compilation,
 but does not optimize as much.
 The default value is 3000.
 This option currently does not affect the mcs51,
 ds390,
 pic14 and pic16 ports.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\series bold
nolospre
\series default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nolospre
\end_layout

\end_inset

 Disable lospre.
 lospre is an advanced redundancy elimination technique,
 essentially an improved variant of global subexpression elimination.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\series bold
allow-unsafe-read
\series default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-allow-unsafe-read
\end_layout

\end_inset

 Allow optimizations to generate unsafe reads.
 This will enable additional optimizations,
 but can result in spurious reads from undefined memory addresses,
 which can be harmful if the target system uses certain ways of doing memory-mapped I/O.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\series bold
nostdlibcall
\series default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nostdlibcall
\end_layout

\end_inset

 Disable the optimization of calls to the standard library.
\end_layout

\begin_layout Subsection
Other Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options other
\end_layout

\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-v
\begin_inset space ~
\end_inset

-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-version
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-version
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-v
\end_layout

\end_inset


\series default
 displays the sdcc version.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-c
\begin_inset space ~
\end_inset

-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-compile-only
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-compile-only
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-c
\end_layout

\end_inset


\series default
 will compile and assemble the source,
 but will not call the linkage editor.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\series default

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series bold
-c1mode
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-c1mode
\end_layout

\end_inset


\series default
 reads the preprocessed source from standard input and compiles it.
 The file name for the assembler output must be specified using the -o option.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-E
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-E
\end_layout

\end_inset


\series default
 Run only the C preprocessor
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Preprocessor
\end_layout

\end_inset

.
 Preprocess all the C source files specified and output the results to standard output.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-syntax-only
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-syntax-only
\end_layout

\end_inset


\series default
\size large
 
\size default
Parse and verify syntax only,
 no output files are produced.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-o
\begin_inset space ~
\end_inset

<path/file>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-o <path/file>
\end_layout

\end_inset


\series default
 The output path where everything will be placed or the file name used for all generated output files.
 If the parameter is a path,
 it must have a trailing slash (or backslash for the Windows binaries) to be recognized as a path.
 Note for Windows users:
 if the path contains spaces,
 it should be surrounded by quotes.
 The trailing backslash should be doubled in order to prevent escaping the final quote,
 for example:
 
\emph on
-o 
\begin_inset Quotes sld
\end_inset

F:
\backslash
Projects
\backslash
test3
\backslash
output 1
\backslash

\backslash

\begin_inset Quotes srd
\end_inset


\emph default
 or put after the final quote,
 for example:
 
\emph on
-o 
\begin_inset Quotes sld
\end_inset

F:
\backslash
Projects
\backslash
test3
\backslash
output 1
\begin_inset Quotes srd
\end_inset


\backslash

\emph default
.
 The path using slashes for directory delimiters can be used too,
 for example:
 
\emph on
-o 
\begin_inset Quotes sld
\end_inset

F:/Projects/test3/output 1/
\begin_inset Quotes srd
\end_inset


\emph default
.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-x
\begin_inset space ~
\end_inset

<type>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-x <type>
\end_layout

\end_inset


\series default
 The specified type overrides the file type that SDCC detected based on the file name extension.
 The currently supported options are 
\begin_inset Quotes sld
\end_inset

c
\begin_inset Quotes srd
\end_inset

,
 
\begin_inset Quotes sld
\end_inset

c-header
\begin_inset Quotes srd
\end_inset

 and 
\begin_inset Quotes sld
\end_inset

none
\begin_inset Quotes srd
\end_inset

.
 The option 
\begin_inset Quotes sld
\end_inset

none
\begin_inset Quotes srd
\end_inset

 restores the default behavior.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\end_layout

\end_inset


\series default
\size large
 
\size default
All functions in the source file will be compiled as 
\emph on
reentrant
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
reentrant
\end_layout

\end_inset

,
 i.e.
 the parameters and local variables will be allocated on the stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset

.
 See section 
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LatexCommand ref
reference "sec:Parameters-and-Local-Variables"
nolink "false"

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 Parameters and Local Variables for more details.
 If this option is used all source files in the project should be compiled with this option.
 It automatically implies -
\series bold

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\backslash
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\series default
-int-long-reent and -
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\begin_inset ERT
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-callee-saves
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function1[,function2][,function3]....

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 The compiler by default uses a caller saves convention for register saving across function calls,
 however this can cause unnecessary register pushing and popping when calling small functions from larger functions.
 This option can be used to switch the register saving convention for the function names specified.
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 no extra code will be generated at the entry and exit (function prologue
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\series default
 and epilogue
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function epilogue
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\series default
) for these functions to save and restore the registers used by these functions,
 this can SUBSTANTIALLY reduce code and improve run time performance of the generated code.
 In the future the compiler (with inter procedural analysis) will be able to determine the appropriate scheme to use for each function call.
 DO NOT use this option for built-in functions such as _mulint...,
 if this option is used for a library function the appropriate library function needs to be recompiled with the same option.
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\backslash
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callee_saves 
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\backslash
#
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pragma callee
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\backslash
_
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saves
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\end_inset

 
\begin_inset CommandInset ref
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reference "ite:callee_saves-function1[,function2[,function3...]]--"
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.
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\begin_layout Labeling
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-
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\backslash
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\begin_inset ERT
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-all-callee-saves
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\series default
 Function of -
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-callee-saves will be applied to all functions by default.
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-
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-
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\begin_layout Plain Layout


\backslash
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\end_inset

 
\series default
When this option is used the compiler will generate debug information.
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AOMF,
 AOMF51
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 format which is commonly used by third party tools.
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-S
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\begin_layout Plain Layout
-S
\end_layout

\end_inset


\series default
\size large
 
\size default
Stop after the stage of compilation proper;
 do not assemble.
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\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-int-long-reent
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-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

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-int-long-reent
\end_layout

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\series default
 Integer (16 bit) and long (32 bit) libraries have been compiled as reentrant.
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 See section Installation for more details.
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\begin_layout Labeling
\labelwidthstring 00.00.0000

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-
\begin_inset ERT
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\backslash
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\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-cyclomatic
\end_layout

\end_inset

 
\series default
This option will cause the compiler to generate an information message for each function in the source file.
 The message contains some 
\emph on
important
\emph default
 information about the function.
 The number of edges and nodes the compiler detected in the control flow graph of the function,
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\emph on
cyclomatic complexity
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\begin_layout Plain Layout
Cyclomatic complexity
\end_layout

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 see section on Cyclomatic Complexity for more details.
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\begin_inset ERT
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\backslash
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\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\series default
 Floating point library is compiled as reentrant
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reentrant
\end_layout

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.
 See section Installation for more details.
\end_layout

\begin_layout Labeling
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\series bold
-
\begin_inset ERT
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\backslash
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\end_layout

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-fsigned-char
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\begin_inset ERT
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\backslash
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-fsigned-char
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\series default
 By default char is 
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\family default
.
 To set the signedness for characters to signed,
 use the option -
\series bold

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series default
-fsigned-char.
 If this option is set and no signedness keyword (unsigned/signed) is given,
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\begin_layout Labeling
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\series bold
-
\begin_inset ERT
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\backslash
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\end_layout

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-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nostdinc
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\series default
 This will prevent the compiler from passing on the default include path to the preprocessor.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nostdlib
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\begin_layout Plain Layout
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nostdlib
\end_layout

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\series default
 This will prevent the compiler from passing on the default library
\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
Libraries
\end_layout

\end_inset

 path to the linker.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-verbose
\begin_inset Index idx
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status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-verbose
\end_layout

\end_inset


\series default
 Shows the various actions the compiler is performing.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-V
\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
-V
\end_layout

\end_inset


\series default
 Shows the actual commands the compiler is executing.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-no-c-code-in-asm
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\begin_layout Plain Layout
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\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-no-c-code-in-asm
\end_layout

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\series default
 Hides your ugly and inefficient c-code from the asm file,
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\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

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-no-peep-comments
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\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_inset

-no-peep-comments
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\series default
 Don't include peep-hole comments in the generated asm files even if -
\series bold

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series default
-fverbose-asm option is specified.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
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\backslash
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\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-i-code-in-asm
\end_layout

\end_inset


\series default
 Include i-codes in the asm file.
 Sounds like noise but is helpful for debugging the compiler itself.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

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pedantic
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\end_inset


\begin_inset Index idx
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\begin_layout Plain Layout
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\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_inset

-less-pedantic
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\end_inset


\series default

\begin_inset CommandInset label
LatexCommand label
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\end_inset

 Disable some of the more pedantic warnings
\begin_inset Index idx
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status collapsed

\begin_layout Plain Layout
Warnings
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.
 For more details,
 see the less_pedantic pragma 
\begin_inset CommandInset ref
LatexCommand vpageref
reference "ite:less_pedantic"
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\end_inset

.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-warning
\begin_inset space ~
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<nnnn>
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\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-disable-warning
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\end_inset


\series default
 Disable specific warning with number <nnnn>.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-Werror
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\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-Werror
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\series default
 Treat all warnings as errors.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-print-search-dirs
\begin_inset Index idx
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status collapsed

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-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-print-search-dirs
\end_layout

\end_inset


\series default
 Display the directories in the compiler's search path
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-vc
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\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-vc
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\end_inset


\series default
 Display errors and warnings using MSVC style,
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\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
IDE
\end_layout

\end_inset

.
 With SDCC both offering a GCC-like (the default) and a MSVC-like
\begin_inset Index idx
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\begin_layout Plain Layout
MSVC output style
\end_layout

\end_inset

 output style,
 integration into most programming editors should be straightforward.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-use-stdout
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\begin_layout Plain Layout
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-use-stdout
\end_layout

\end_inset


\series default
 Send errors and warnings to stdout instead of stderr.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-Wa
\begin_inset space ~
\end_inset

asmOption[,asmOption]
\series default

\begin_inset Index idx
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pageformat default
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\begin_layout Plain Layout
-Wa asmOption[,asmOption]
\end_layout

\end_inset

...
 Pass the asmOption to the assembler
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Options assembler
\end_layout

\end_inset


\begin_inset Index idx
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pageformat default
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\begin_layout Plain Layout
Assembler options
\end_layout

\end_inset

.
 See file sdcc/sdas/doc/asmlnk.txt for assembler options.cd
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\begin_layout Labeling
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\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-std-<arg>
\series default
 Determine the language standard.
 For enhanced compatibility with other compilers,
 
\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-std
\series default
 can also be used with a single dash (i.e.
 
\series bold
-std
\series default
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\series bold
=
\series default
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\series bold

\begin_inset space \textvisiblespace{}
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\series default
 (whitespace) as delimiter.
 The language standard,
 specified via 
\series bold
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\series default
,
 can be one of the following:
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\begin_deeper
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\labelwidthstring 00.00.0000

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\begin_layout Plain Layout


\backslash
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-std-c89
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\series default
 Follow the ISO/IEC 9899 First Edition standard (ANSI C89 / ISO C90).
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\series bold
c89
\series default
,
 
\series bold
iso9899:1990
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\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
c94 
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-
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\begin_layout Plain Layout


\backslash
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\end_inset

-std-sdcc99
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\series default
 Follow the ISO/IEC 9899 First Edition standard as modified in amendment 1.
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\series bold
c95,
 iso9899:199409
\end_layout

\begin_layout Labeling
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-std-sdcc99
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\series default
 Follow the ISO/IEC 9899 Second Edition standard (ISO C99).
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\series bold
iso9899:1999
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
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\backslash
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-std-sdcc11
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\series default
 Follow the ISO/IEC 9899 Third Edition standard (ISO C11).
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\series bold
iso9899:2011
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
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-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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-std-sdcc17
\end_layout

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 Follow the ISO/IEC 9899 Fourth Edition standard (ISO C17).
 Alternative spellings:
 
\series bold
iso9899:2017
\series default
,
 
\series bold
c18
\series default
,
 
\series bold
iso9899:2018
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\begin_layout Labeling
\labelwidthstring 00.00.0000

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c23 
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\backslash
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-std-sdcc23
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\series default
 Follow the ISO/IEC 9899 Fifth Edition standard (ISO C23).
 Alternative spelling:
 
\series bold
c2x
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
c2y 
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\backslash
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-std-sdcc2y
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 Enable features anticipated for the Sixth Edition standard (currently abbreviated ISO C2y).
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\labelwidthstring 00.00.0000

\series bold
sdcc90 
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\begin_inset ERT
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\backslash
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-std-sdcc89
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 Generally follow ANSI C89 / ISO C90,
 but allow some SDCC behaviour that conflicts with the standard.
 Alternative spelling:
 
\series bold
sdcc89
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\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
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-std-sdcc99
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 Generally follow ISO C99,
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\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
sdcc11 
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-std-sdcc11
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 Generally follow ISO C11,
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\labelwidthstring 00.00.0000

\series bold
sdcc17 
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\begin_inset ERT
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-std-sdcc17
\end_layout

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\series default
 Generally follow ISO C17,
 but allow some SDCC behaviour that conflicts with the standard.
 Alternative spelling:
 
\series bold
sdcc18
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
sdcc23 
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-
\begin_inset ERT
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\begin_layout Plain Layout


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\end_inset

-std-sdcc23
\end_layout

\end_inset


\series default
 Generally follow ISO C23,
 but allow some SDCC behaviour that conflicts with the standard.
 Alternative spelling:
 
\series bold
sdcc2x
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
sdcc2y 
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\begin_layout Plain Layout
-
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\end_inset

-std-sdcc2y
\end_layout

\end_inset


\series default
 Generally follow ISO C2y,
 but allow some SDCC behaviour that conflicts with the standard.
\end_layout

\end_deeper
\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

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\begin_layout Plain Layout
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-codeseg <Value>
\end_layout

\end_inset


\begin_inset CommandInset label
LatexCommand label
name "lyx:-codeseg"

\end_inset


\begin_inset space ~
\end_inset

<Name> The name to be used for the code
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
code
\end_layout

\end_inset

 segment,
 default CSEG.
 This is useful if you need to tell the compiler to put the code in a special segment so you can later on tell the linker to put this segment in a special place in memory.
 Can be used for instance when using bank switching to put the code in a bank.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
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\backslash
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\end_layout

\end_inset

-constseg
\series default

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status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-constseg <Value>
\end_layout

\end_inset


\begin_inset space ~
\end_inset

<Name> The name to be used for the const
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
const
\end_layout

\end_inset

 segment,
 default CONST.
 This is useful if you need to tell the compiler to put the const data in a special segment so you can later on tell the linker to put this segment in a special place in memory.
 Can be used for instance when using bank switching to put the const data in a bank.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-fdollars-in-identifiers
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\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-fdollars-in-identifiers
\end_layout

\end_inset


\series default
 Permit '$' as an identifier character.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
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\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-more-pedantic
\series default

\begin_inset Index idx
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\begin_layout Plain Layout
-
\begin_inset ERT
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\begin_layout Plain Layout


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\end_inset

-more-pedantic
\end_layout

\end_inset


\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
pedantic
\end_layout

\end_inset

 Actually this is 
\series bold
\emph on
not
\series default
\emph default
 a SDCC compiler option but if you want 
\emph on
more
\emph default
 warnings you can use a separate tool dedicated to syntax checking like splint
\begin_inset CommandInset label
LatexCommand label
name "lyx:more-pedantic-SPLINT"

\end_inset


\begin_inset Index idx
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\begin_layout Plain Layout
lint (syntax checking tool)
\end_layout

\end_inset

 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.splint.org
\end_layout

\end_inset

.
 To make your source files parseable by splint you will have to include 
\family sans
lint.h
\family default

\begin_inset Index idx
range none
pageformat default
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\begin_layout Plain Layout
splint (syntax checking tool)
\end_layout

\end_inset

 in your source file and add brackets around extended keywords (like 
\family sans

\begin_inset Quotes sld
\end_inset

__at
\begin_inset space ~
\end_inset


\series bold
(
\series default
0xab
\series bold
)
\series default

\begin_inset Quotes srd
\end_inset


\family default
 and 
\family sans

\begin_inset Quotes sld
\end_inset

__interrupt
\begin_inset space ~
\end_inset

(2)
\begin_inset Quotes srd
\end_inset


\family default
).
 
\begin_inset Newline newline
\end_inset

Splint has an excellent on line manual at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.splint.org/manual/
\end_layout

\end_inset

 and it's capabilities go beyond pure syntax checking.
 You'll need to tell splint the location of SDCC's include files so a typical command line could look like this:
 
\begin_inset Newline newline
\end_inset


\family sans
splint
\begin_inset space ~
\end_inset

-I
\begin_inset space ~
\end_inset

/usr/local/share/sdcc/include/mcs51/
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

myprogram.c
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\end_layout

\end_inset


\begin_inset CommandInset label
LatexCommand label
name "lyx:--use-non-free"

\end_inset

 Search / include non-free licensed libraries and header files,
 located under the non-free directory - see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Search-Paths"
nolink "false"

\end_inset


\end_layout

\begin_layout Subsection
Linker Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options linker
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Linker options
\end_layout

\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\series default

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series bold
-lib-path
\begin_inset Index idx
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pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-lib-path <path>
\end_layout

\end_inset


\series default

\begin_inset space ~
\end_inset

<absolute path to additional libraries> This option is passed to the linkage editor's additional libraries
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Libraries
\end_layout

\end_inset

 search path.
 The path name must be absolute.
 Additional library files may be specified in the command line.
 See section Compiling programs for more details.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-L
\begin_inset space ~
\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-L <path>
\end_layout

\end_inset


\series default

\begin_inset space ~
\end_inset

<absolute path to additional libraries> Same as above.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xram-loc
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xram-loc <Value>
\end_layout

\end_inset


\begin_inset space ~
\end_inset

<Value> The start location of the external ram
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

xdata (mcs51,
 ds390 named address space)
\end_layout

\end_inset

,
 default value is 0.
 The value entered can be in Hexadecimal or Decimal format,
 e.g.:
 -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xram-loc 0x8000 or -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xram-loc 32768.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-code-loc
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-code-loc <Value>
\end_layout

\end_inset


\begin_inset space ~
\end_inset

<Value> The start location of the code
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
code
\end_layout

\end_inset

 segment,
 default value 0.
 Note when this option is used the interrupt vector table
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt vector table
\end_layout

\end_inset

 is also relocated to the given address.
 The value entered can be in Hexadecimal or Decimal format,
 e.g.:
 -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-code-loc 0x8000 or -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-code-loc 32768.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-loc
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-loc <Value>
\end_layout

\end_inset


\begin_inset space ~
\end_inset

<Value> The value entered can be in Hexadecimal or Decimal format,
 e.g.
 -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-loc 0x20 or -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-loc 32.
\end_layout

\begin_deeper
\begin_layout Standard
For stm8,
 by default the stack is placed at the device-specific reset value.
 By using this option,
 the stack can be placed anywhere in the lower 16-bits of the stm8 memory space.
 This is particularly useful for working around the stack roll-over antifeature present in some stm8 devices.
\end_layout

\end_deeper
\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-xstack-loc
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack-loc <Value>
\end_layout

\end_inset


\begin_inset space ~
\end_inset

<Value> By default the external stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
xstack
\end_layout

\end_inset

 is placed after the __pdata
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

pdata (mcs51,
 ds390 named address space)
\end_layout

\end_inset

 segment.
 Using this option the xstack can be placed anywhere in the external memory space of the 8051.
 The value entered can be in Hexadecimal or Decimal format,
 e.g.
 -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack-loc 0x8000 or -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack-loc 32768.
 The provided value should not overlap any other memory areas such as the pdata or xdata segment and with enough space for the current application.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-data-loc
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-data-loc <Value>
\end_layout

\end_inset


\begin_inset space ~
\end_inset

<Value> The start location of the internal ram data
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

data (mcs51,
 ds390 named address space)
\end_layout

\end_inset

 segment.
 The value entered can be in Hexadecimal or Decimal format,
 eg.
 -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-data-loc 0x20 or -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-data-loc 32.
 (By default,
 the start location of the internal ram data segment  is set as low as possible in memory,
 taking into account the used register banks and the bit segment at address 0x20.
 For example if register banks 0 and 1 are used without bit variables,
 the data segment will be set,
 if -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-data-loc is not used,
 to location 0x10.)
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-idata-loc
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-idata-loc <Value>
\end_layout

\end_inset


\begin_inset space ~
\end_inset

<Value> The start location of the indirectly addressable internal ram
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

idata (mcs51,
 ds390 named address space)
\end_layout

\end_inset

 of the 8051,
 default value is 0x80.
 The value entered can be in Hexadecimal or Decimal format,
 eg.
 -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-idata-loc 0x88 or -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-idata-loc 136.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-bit-loc
\series default

\begin_inset space ~
\end_inset

<Value> The start location of the bit
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
bit
\end_layout

\end_inset

 addressable internal ram of the 8051.
 This is 
\emph on
not
\emph default
 implemented yet.
 Instead an option can be passed directly to the linker:
 -Wl
\begin_inset space ~
\end_inset

-bBSEG=<Value>.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-out-fmt-ihx
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-out-fmt-ihx
\end_layout

\end_inset

 
\series default
The linker output (final object code) is in Intel Hex format.
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Intel hex format
\end_layout

\end_inset

 This is the default option.
 The format itself is documented in the documentation of srecord
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
srecord (bin,
 hex,
 ...
 tool)
\end_layout

\end_inset

.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-out-fmt-s19
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-out-fmt-s19
\end_layout

\end_inset

 
\series default
The linker output (final object code) is in Motorola S19 format
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Motorola S19 format
\end_layout

\end_inset

.
 The format itself is documented in the documentation of srecord.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-out-fmt-elf
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-out-fmt-s19
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
HC08!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-out-fmt-elf
\end_layout

\end_inset

 
\series default
The linker output (final object code) is in ELF format
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
ELF format
\end_layout

\end_inset

.
 (Currently only supported for the HC08
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
HC08
\end_layout

\end_inset

,
 S08 and STM8 processors).
 When used with –debug,
 the debug info is in DWARF format instead of CDB.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-Wl
\begin_inset space ~
\end_inset

linkOption[,linkOption]
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-Wl linkOption[,linkOption]
\end_layout

\end_inset


\begin_inset CommandInset label
LatexCommand label
name "lyx:-Wl option"

\end_inset

...
 Pass the linkOption to the linker.
 If a bootloader is used an option like 
\begin_inset Quotes sld
\end_inset

-Wl
\begin_inset space ~
\end_inset

-bCSEG=0x1000
\begin_inset Quotes srd
\end_inset

 would be typical to set the start of the code segment.
 Either use the double quotes around this option or use no space (e.g.
 -Wl-bCSEG=0x1000).
 See also #pragma constseg and #pragma codeseg in section
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Pragmas"
nolink "false"

\end_inset

.
 File sdcc/sdas/doc/asmlnk.txt has more on linker options.
\end_layout

\begin_layout Subsection
MCS51 Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options MCS51
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
MCS51 options
\end_layout

\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-small
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-small
\end_layout

\end_inset


\series default
\size large
 
\size default
Generate code for Small model programs,
 see section Memory Models for more details.
 This is the default model.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-model-medium
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-model-medium
\end_layout

\end_inset


\series default
 Generate code for Medium model programs,
 see section Memory Models for more details.
 If this option is used all source files in the project have to be compiled with this option.
 It must also be used when invoking the linker.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-model-large
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-large
\end_layout

\end_inset


\series default
 Generate code for Large model programs,
 see section Memory Models for more details.
 If this option is used all source files in the project have to be compiled with this option.
 It must also be used when invoking the linker.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-huge
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-huge
\end_layout

\end_inset


\series default
 Generate code for Huge model programs,
 see section Memory Models for more details.
 If this option is used all source files in the project have to be compiled with this option.
 It must also be used when invoking the linker.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack
\end_layout

\end_inset


\series default
 Uses a pseudo stack in the __pdata
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

pdata (mcs51,
 ds390 named address space)
\end_layout

\end_inset

 area (usually the first 256 bytes in the external ram) for allocating variables and passing parameters.
 See section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:External-Stack"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset

 External Stack for more details.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-iram-size
\series default

\begin_inset space ~
\end_inset

<Value>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-iram-size <Value>
\end_layout

\end_inset

 Causes the linker to check if the internal ram usage is within limits of the given value.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xram-size
\series default

\begin_inset space ~
\end_inset

<Value>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xram-size <Value>
\end_layout

\end_inset

 Causes the linker to check if the external ram usage is within limits of the given value.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-code-size
\series default

\begin_inset space ~
\end_inset

<Value>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-code-size <Value>
\end_layout

\end_inset

 Causes the linker to check if the code memory usage is within limits of the given value.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-size
\series default

\begin_inset space ~
\end_inset

<Value>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-size <Value>
\end_layout

\end_inset

 Causes the linker to check if there is at minimum <Value> bytes for stack.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-acall-ajmp
\series default

\begin_inset space ~
\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-acall-ajmp
\end_layout

\end_inset

 Replaces the three byte instructions lcall/ljmp with the two byte instructions acall/ajmp.
 Only use this option if your code is in the same 2k block of memory.
 You may need to use this option for some 8051 derivatives which lack the lcall/ljmp instructions.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-ret-without-call
\series default

\begin_inset space ~
\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-ret-without-call
\end_layout

\end_inset

 Causes the code generator to insert an extra lcall or acall instruction whenever it needs to use a ret instruction in a context other than a function returning.
 This option is needed when using the Infineon
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Infineon
\end_layout

\end_inset

 XC800 series microcontrollers to keep its Memory Extension Stack balanced.
\end_layout

\begin_layout Subsection
DS390 / DS400 Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options DS390
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS390
\end_layout

\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-flat24
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS390!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-flat24
\end_layout

\end_inset


\size large
 
\size default
Generate 24-bit flat mode code.
 This is the one and only that the ds390 code generator supports right now and is default when using 
\emph on
-mds390
\emph default
.
 See section Memory Models for more details.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-protect-sp-update
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS390!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-protect-sp-update
\end_layout

\end_inset


\series default
 disable interrupts during ESP:SP updates.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-10bit
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS390!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-10bit
\end_layout

\end_inset

 Generate code for the 10 bit stack mode of the Dallas DS80C390 part.
 This is the one and only that the ds390 code generator supports right now and is default when using 
\emph on
-mds390
\emph default
.
 In this mode,
 the stack is located in the lower 1K of the internal RAM,
 which is mapped to 0x400000.
 Note that the support is incomplete,
 since it still uses a single byte as the stack pointer.
 This means that only the lower 256 bytes of the potential 1K stack space will actually be used.
 However,
 this does allow you to reclaim the precious 256 bytes of low RAM for use for the DATA and IDATA segments.
 The compiler will not generate any code to put the processor into 10 bit stack mode.
 It is important to ensure that the processor is in this mode before calling any re-entrant functions compiled with this option.
 In principle,
 this should work with the 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\end_layout

\end_inset


\emph default
 option,
 but that has not been tested.
 It is incompatible with the 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack
\end_layout

\end_inset


\emph default
 option.
 It also only makes sense if the processor is in 24 bit contiguous addressing mode (see the 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-flat24 option
\emph default
).
\series bold

\begin_inset Note Note
status collapsed

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-8-bit - switches off the 10-bit mode
\end_layout

\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-probe
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS390!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-probe
\end_layout

\end_inset


\series default
 insert call to function __stack_probe at each function prologue.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-tini-libid
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS390!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-tini-libid
\end_layout

\end_inset


\series default
 <nnnn> LibraryID used in -mTININative.
 
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-accelerator
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS390!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-accelerator
\end_layout

\end_inset


\series default
 generate code for DS390 Arithmetic Accelerator.
 
\end_layout

\begin_layout Subsection
Options common to all z80-related ports (z80,
 z180,
 r2k,
 r3ka,
 sm83,
 tlcs90,
 ez80_z80)
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-std-crt0
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-std-crt0
\end_layout

\end_inset

 When linking,
 skip the standard crt0.rel object file.
 You must provide your own crt0.rel for your system when linking.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-callee-saves-bc
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-callee-saves-bc
\end_layout

\end_inset


\size large
 
\size default
Force a called function to always save BC.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-codeseg
\series default

\begin_inset space ~
\end_inset

<Value>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-codeseg <Value>
\end_layout

\end_inset

 Use <Value> for the code segment name.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-constseg
\series default

\begin_inset space ~
\end_inset

<Value>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-constseg <Value>
\end_layout

\end_inset

 Use <Value> for the const segment name.
\end_layout

\begin_layout Subsection
Z80 Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options Z80
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80
\end_layout

\end_inset

 (apply to z80,
 z180,
 r2k,
 r3ka,
 tlcs90,
 ez80_z80)
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-portmode=
\series default
<Value>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-portmode=<Value>
\end_layout

\end_inset

 Determinate PORT I/O mode (<Value> is z80 or z180).
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-asm=
\series default
<Value>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-asm=<Value>
\end_layout

\end_inset

 Define assembler name (<Value> is rgbds,
 sdasz80,
 isas or z80asm).
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-reserve-regs-iy
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-reserve-regs-iy
\end_layout

\end_inset


\size large
 
\size default
This option tells the compiler that it is not allowed to use register pair iy.
 The option can be useful for systems where iy is reserved for the OS.
 This option is incompatible with -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-fomit-frame-pointer.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-fno-omit-frame-pointer
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-fno-omit-frame-pointer
\end_layout

\end_inset


\size large
 
\size default
Never omit the frame pointer.
\end_layout

\begin_layout Subsection
SM83 Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options GBZ80
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
SM83
\end_layout

\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-bo
\series default

\begin_inset space ~
\end_inset

<Num>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
GBZ80!Options!-bo <Num>
\end_layout

\end_inset

 Use code bank <Num>.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-ba
\series default

\begin_inset space ~
\end_inset

<Num>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
GBZ80!Options!-ba <Num>
\end_layout

\end_inset

 Use data bank <Num>.
\end_layout

\begin_layout Subsection
STM8 Options
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
Options STM8
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
STM8 options
\end_layout

\end_inset


\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-medium
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-medium
\end_layout

\end_inset


\series default
 Generate code for Medium model programs,
 see section Memory Models for more details.
 This is the default model.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-large
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-large
\end_layout

\end_inset


\series default
 Generate code for Large model programs,
 see section Memory Models for more details.
 If this option is used all source files in the project have to be compiled with this option.
 It must also be used when invoking the linker.
\end_layout

\begin_layout Subsection
MOS6502 Options
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
Options MOS6502
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
MOS6502 options
\end_layout

\end_inset

 (apply to mos6502,
 mos65c02)
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-small
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-small
\end_layout

\end_inset


\series default
 Generate code for small model programs,
 see section Memory Models for more details.
 
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-large
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-large
\end_layout

\end_inset


\series default
 Generate code for large model programs,
 see section Memory Models for more details.
 This is the default memory model.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-zp-spill
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-zp-spill
\end_layout

\end_inset


\series default
 Force the compiler to spill registers to 16-bit addressable memory (xdata) instead of Page Zero.
 When running out of Page Zero space,
 this option will allow to free many Page Zero locations at the expense of slightly larger and slower code
\end_layout

\begin_layout Subsection
Intermediate Dump Options
\begin_inset CommandInset label
LatexCommand label
name "subsec:Intermediate-Dump-Options"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options intermediate dump
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Intermediate dump options
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The following options are provided for the purpose of retargetting and debugging the compiler.
 They provide a means to dump the intermediate code (iCode
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
iCode
\end_layout

\end_inset

) generated by the compiler in human readable form at various stages of the compilation process.
 More on iCodes see chapter 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:The-anatomy-of"
nolink "false"

\end_inset

 
\begin_inset Quotes srd
\end_inset

The anatomy of the compiler
\begin_inset Quotes srd
\end_inset

.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-dum-ast
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-dump-ast
\end_layout

\end_inset


\series default
 This option will cause the compiler to dump the abstract syntax tree to the econsole.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-dump-i-code
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-dump-i-code
\end_layout

\end_inset


\size large
 
\series default
\size default
Will dump iCodes at various stages into files named 
\emph on
<source filename>.dump<stage>
\emph default
.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-dump-graphs
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-dump-graphs
\end_layout

\end_inset


\size large
 
\series default
\size default
Will dump internal representations as graphviz .dot files.
 Depending on other options,
 this can include the control-flow graph at lospre,
 insertion of bank selection instructions or register allocation and the conflict graph and tree-decomposition at register allocation.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-fverbose-asm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-gen-comments
\end_layout

\end_inset


\series default
 Include code generator and peep-hole comments in the generated asm files.
\end_layout

\begin_layout Subsection
Redirecting output on Windows Shells
\end_layout

\begin_layout Standard
By default SDCC writes its error messages to 
\begin_inset Quotes sld
\end_inset

standard error
\begin_inset Quotes srd
\end_inset

.
 To force all messages to 
\begin_inset Quotes sld
\end_inset

standard output
\begin_inset Quotes srd
\end_inset

 use 
\series bold
-
\series default
\emph on

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series bold
\emph default
-
\series default
use-stdout
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-stdout
\end_layout

\end_inset

.
 Additionally,
 if you happen to have visual studio installed in your Windows machine,
 you can use it to compile your sources using a custom build and the SDCC -
\emph on

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\emph default
-vc
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-vc
\end_layout

\end_inset

 option.
 Something like this should work:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\series bold
c:
\backslash
sdcc
\backslash
bin
\backslash
sdcc.exe -
\series default
\emph on

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series bold
\emph default
-vc -
\series default
\emph on

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series bold
\emph default
-model-large -c $(InputPath)
\end_layout

\begin_layout Section
Environment variables
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Environment variables
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC recognizes the following environment variables:
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
SDCC_LEAVE_SIGNALS
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Environment variables!SDCC
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

LEAVE
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

SIGNALS
\end_layout

\end_inset


\series default
 SDCC installs a signal handler
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
signal handler
\end_layout

\end_inset

 to be able to delete temporary files after an user break (^C) or an exception.
 If this environment variable is set,
 SDCC won't install the signal handler in order to be able to debug SDCC.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
TMP,
\begin_inset space ~
\end_inset

TEMP,
\begin_inset space ~
\end_inset

TMPDIR
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Environment variables!TMP,
 TEMP,
 TMPDIR
\end_layout

\end_inset


\series default
 Path,
 where temporary files will be created.
 The order of the variables is the search order.
 In a standard *nix environment these variables are not set,
 and there's no need to set them.
 On Windows it's recommended to set one of them.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
SDCC_HOME
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Environment variables!SDCC
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

HOME
\end_layout

\end_inset


\series default
 Path,
 see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Install-paths"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset


\begin_inset Quotes sld
\end_inset

 Install Paths
\begin_inset Quotes srd
\end_inset

.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
SDCC_INCLUDE
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Environment variables!SDCC
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

INCLUDE
\end_layout

\end_inset


\series default
 Path,
 see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Search-Paths"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset


\begin_inset Quotes sld
\end_inset

Search Paths
\begin_inset Quotes srd
\end_inset

.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series bold
SDCC_LIB
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Environment variables!SDCC
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

LIB
\end_layout

\end_inset


\series default
 Path,
 see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Search-Paths"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset


\begin_inset Quotes sld
\end_inset

Search Paths
\begin_inset Quotes srd
\end_inset

..
\end_layout

\begin_layout Standard
There are some more environment variables recognized by SDCC,
 but these are mainly used for debugging purposes.
 They can change or disappear very quickly,
 and won't be documented
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
if you are curious search in SDCC's sources for 
\family typewriter

\begin_inset Quotes sld
\end_inset

getenv
\begin_inset Quotes srd
\end_inset


\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Environment variables!undocumented
\end_layout

\end_inset

.
\end_layout

\begin_layout Section
SDCC Language Extensions
\end_layout

\begin_layout Standard
SDCC supports some language extensions useful for embedded systems.
 These include named address spaces (see also section 5.1 of the Embedded C standard).
 SDCC supports both intrinsic named address spaces (which ones are supported depends on the target architecture) and non-intrinsic named address spaces (defined by the user using the keyword __addressmod,
 they are particularly useful with custom bank-switching hardware).
 Unlike the Embedded C standard,
 SDCC allows local variables to have an intrinsic named address space even when not explicitly declared as static or extern.
 Depending on the target architecture,
 support can be limited to objects in such address spaces and exclude pointer-based access to those.
\end_layout

\begin_layout Subsection
MCS51/DS390 intrinsic named address spaces
\end_layout

\begin_layout Standard
SDCC supports the following MCS51-specific intrinsic address spaces:
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename MCS51_named.svg

\end_inset


\end_layout

\begin_layout Subsubsection
__data
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

data (mcs51,
 ds390 named address space)
\end_layout

\end_inset

 / __near
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

near (named address space)
\end_layout

\end_inset


\end_layout

\begin_layout Standard
This is the 
\series bold
default
\series default
 (generic) address space for the Small Memory model.
 Variables in this address space will be allocated in the directly addressable portion of the internal RAM of a 8051,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__data unsigned char test_data;
\end_layout

\begin_layout Standard
Writing 0x01 to this variable generates the assembly code:
\end_layout

\begin_layout Verse

\family typewriter
75*00 01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

_test_data,#0x01
\end_layout

\begin_layout Subsubsection
__xdata
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

xdata (mcs51,
 ds390 named address space)
\end_layout

\end_inset

 / __far
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

far (named address space)
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Variables in this address space will be placed in the external RAM.
 This is the 
\series bold
default
\series default
 (generic) address space for the Large Memory model,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__xdata unsigned char test_xdata;
\end_layout

\begin_layout Standard
Writing 0x01 to this variable generates the assembly code:
\end_layout

\begin_layout Verse

\family typewriter
90s00r00
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dptr,#_test_xdata
\begin_inset Newline newline
\end_inset

74
\begin_inset space ~
\end_inset

01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,#0x01
\begin_inset Newline newline
\end_inset

F0
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

movx
\begin_inset space ~
\end_inset

@dptr,a 
\end_layout

\begin_layout Subsubsection
__idata
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

idata (mcs51,
 ds390 named address space)
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Variables in this address space will be allocated into the indirectly addressable portion of the internal ram of a 8051,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__idata unsigned char test_idata;
\end_layout

\begin_layout Standard
Writing 0x01 to this variable generates the assembly code:
\end_layout

\begin_layout Verse

\family typewriter
78r00
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

r0,#_test_idata
\begin_inset Newline newline
\end_inset

76
\begin_inset space ~
\end_inset

01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

@r0,#0x01
\end_layout

\begin_layout Standard
Please note,
 the first 128 byte of idata physically access the same RAM as the data memory.
 The original 8051 had 128 byte idata memory,
 nowadays most devices have 256 byte idata memory.
 The stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset

 is located in idata memory (unless 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--xstack
\end_layout

\end_inset

 is specified).
\end_layout

\begin_layout Subsubsection
__pdata
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

pdata (mcs51,
 ds390 named address space)
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Paged xdata access is just as straightforward as using the other addressing modes of a 8051.
 It is typically located at the start of xdata and has a maximum size of 256 bytes.
 The following example writes 0x01 to the pdata variable.
 Please note,
 pdata access physically accesses xdata memory.
 The high byte of the address is determined by port P2 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
P2 (mcs51 sfr)
\end_layout

\end_inset

(or in case of some 8051 variants by a separate Special Function Register,
 see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:MCS51-variants"
nolink "false"

\end_inset

).
 This is the 
\series bold
default
\series default
 (generic) address space for the Medium Memory model,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__pdata unsigned char test_pdata;
\end_layout

\begin_layout Standard
Writing 0x01 to this variable generates the assembly code:
\end_layout

\begin_layout Verse

\family typewriter
78r00
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r0,#_test_pdata
\begin_inset Newline newline
\end_inset

74 01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,#0x01
\begin_inset Newline newline
\end_inset

F2
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

movx @r0,a
\end_layout

\begin_layout Standard
If the -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack
\end_layout

\end_inset

 option is used the pdata memory area is followed by the xstack memory area and the sum of their sizes is limited to 256 bytes.
\end_layout

\begin_layout Subsubsection
__code
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

code
\end_layout

\end_inset


\end_layout

\begin_layout Standard
'Variables' in this address space will be placed in the code memory:
\end_layout

\begin_layout Verse

\family typewriter
__code unsigned char test_code;
\end_layout

\begin_layout Standard
Read access to this variable generates the assembly code:
\end_layout

\begin_layout Verse

\family typewriter
90s00r6F
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov dptr,#_test_code
\begin_inset Newline newline
\end_inset

E4
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

clr a
\begin_inset Newline newline
\end_inset

93
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

movc a,@a+dptr 
\end_layout

\begin_layout Standard

\family typewriter
char
\family default
 indexed arrays of characters in code memory can be accessed efficiently:
\end_layout

\begin_layout Verse

\family typewriter
__code char test_array[] = {'c','h','e','a','p'};
 
\end_layout

\begin_layout Standard
Read access to this array using an 8-bit unsigned index generates the assembly code:
\end_layout

\begin_layout Verse

\family typewriter
E5*00
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,_index 
\end_layout

\begin_layout Verse

\family typewriter
90s00r41
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov dptr,#_test_array
\end_layout

\begin_layout Verse

\family typewriter
93
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

movc a,@a+dptr 
\end_layout

\begin_layout Subsubsection
__bit
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

bit
\end_layout

\end_inset


\end_layout

\begin_layout Standard
This is a data-type and an address space.
 When a variable is declared as a bit,
 it is allocated into the bit addressable memory of 8051,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__bit test_bit;
\end_layout

\begin_layout Standard
Writing 1 to this variable generates the assembly code:
\end_layout

\begin_layout Verse

\family typewriter
D2*00
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

setb
\begin_inset space ~
\end_inset

_test_bit
\end_layout

\begin_layout Standard
The bit addressable memory consists of 128 bits which are located from 0x20 to 0x2f in data memory.
\begin_inset Newline newline
\end_inset

Apart from this 8051 specific intrinsic named address space most architectures support ANSI-C bit-fields
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
bit-fields
\end_layout

\end_inset


\begin_inset Foot
status collapsed

\begin_layout Plain Layout
Not really meant as examples,
 but nevertheless showing what bit-fields are about:
 device/include/mc68hc908qy.h and support/regression/tests/bitfields.c
\end_layout

\end_inset

.
 In accordance with ISO/IEC 9899 bits and bitfields without an explicit signed modifier are implemented as unsigned.
\end_layout

\begin_layout Subsubsection
__sfr
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sfr
\end_layout

\end_inset

 / __sfr16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sfr16
\end_layout

\end_inset

 / __sfr32
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sfr32
\end_layout

\end_inset

 / __sbit
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sbit
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Like the __bit keyword,
 
\emph on
__sfr / __sfr16 / __sfr32 / __sbit
\emph default
 signify both a data-type and named address space,
 they are used to describe the 
\emph on
s
\emph default
pecial 
\emph on
f
\emph default
unction 
\emph on
r
\emph default
egisters and special 
\emph on
__bit
\emph default
 variables of a 8051,
 eg:
\end_layout

\begin_layout Verse

\family typewriter
__sfr __at
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

at
\end_layout

\end_inset

 (0x80) P0;
\begin_inset space ~
\end_inset

 /* special function register P0 at location 0x80 */
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

/* 16 bit special function register combination for timer 0
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 with the high byte at location 0x8C and the low byte at location 0x8A */
\begin_inset Newline newline
\end_inset

__sfr16 __at (0x8C8A) TMR0;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

__sbit __at
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

at
\end_layout

\end_inset

 (0xd7) CY;
\begin_inset space ~
\end_inset

 /* CY (Carry Flag
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Flags
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Carry flag
\end_layout

\end_inset

) */
\end_layout

\begin_layout Standard
Special function registers which are located on an address dividable by 8 are bit-addressable,
 an 
\emph on
__sbit
\emph default
 addresses a specific bit within these sfr.
\begin_inset Newline newline
\end_inset

16 Bit and 32 bit special function register combinations which require a certain access order are better not declared using 
\emph on
__sfr16
\emph default
 or 
\emph on
__sfr32.

\emph default
 Although SDCC usually accesses them Least Significant Byte (LSB) first,
 this is not guaranteed.
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
Please note,
 if you use a header file which was written for another compiler then the __sfr / __sfr16 / __sfr32 / __sbit intrinsic named address spaces will most likely be 
\emph on
not
\emph default
 compatible.
 Specifically the syntax 
\family typewriter

\begin_inset space ~
\end_inset

sfr P0 = 0x80;
\begin_inset space ~
\end_inset


\family default
 is compiled 
\emph on
without warning
\emph default
 by SDCC to an assignment of 0x80 to a variable called P0
\family typewriter
.

\family default
 
\series bold
Nevertheless with the file 
\family typewriter
compiler.h
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
compiler.h (include file)
\end_layout

\end_inset


\family default
 it is possible to write header files
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Header files
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Include files
\end_layout

\end_inset

 which can be shared among different compilers (see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Porting-code-to-other-compilers"
nolink "false"

\end_inset

).
 
\end_layout

\begin_layout Subsubsection
Pointers
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Pointer
\end_layout

\end_inset

 to MCS51/DS390 intrinsic named address spaces
\end_layout

\begin_layout Standard
SDCC allows (via language extensions) pointers to explicitly point to any of the named address spaces
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Memory model
\end_layout

\end_inset

 of the 8051.
 In addition to the explicit pointers,
 the compiler uses (by default) generic pointers which can be used to point to any of the memory spaces.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Pointer declaration examples:
\end_layout

\begin_layout Verse

\family typewriter
/* pointer physically in internal ram pointing to object in external ram */
\begin_inset Newline newline
\end_inset

__xdata unsigned char * __data p;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

/* pointer physically in external ram pointing to object in internal ram */
\begin_inset Newline newline
\end_inset

__data unsigned char * __xdata p;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

/* pointer physically in code rom pointing to data in xdata space */
\begin_inset Newline newline
\end_inset

__xdata unsigned char * __code p;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

/* pointer physically in code space pointing to data in code space */
\begin_inset Newline newline
\end_inset

__code unsigned char * __code p;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

/* generic pointer physically located in xdata space */
\begin_inset Newline newline
\end_inset

unsigned char * __xdata p;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

/* generic pointer physically located in default memory space */
\begin_inset Newline newline
\end_inset

unsigned char * p;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

/* the following is a function pointer
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
function pointer
\end_layout

\end_inset

 physically located in data space */
\begin_inset Newline newline
\end_inset

char (* __data fp)(void);
\end_layout

\begin_layout Standard
Well you get the idea.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

All unqualified pointers are treated as 3-byte (4-byte for the ds390) 
\emph on
generic
\emph default
 pointers.
\size small

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\size default
The highest order byte of the 
\emph on
generic
\emph default
 pointers contains the data space information.
 Assembler support routines are called whenever data is stored or retrieved using 
\emph on
generic
\emph default
 pointers.
 These are useful for developing reusable library
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Libraries
\end_layout

\end_inset

 routines.
 Explicitly specifying the pointer
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Pointer
\end_layout

\end_inset

 type will generate the most efficient code.
\end_layout

\begin_layout Subsubsection
Notes on MCS51 memory
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
MCS51 memory
\end_layout

\end_inset

 layout
\end_layout

\begin_layout Standard
The 8051 family of microcontrollers have a minimum of 128 bytes of internal RAM memory 
\emph on
__data
\emph default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

data (mcs51,
 ds390 named address space)
\end_layout

\end_inset

 which is structured as follows:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

- Bytes 00-1F - 32 bytes to hold up to 4 banks of the registers R0 to R7,
\begin_inset Newline newline
\end_inset

- Bytes 20-2F - 16 bytes to hold 128 bit
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
bit
\end_layout

\end_inset

 variables and,
\begin_inset Newline newline
\end_inset

- Bytes 30-7F - 80 bytes for general purpose use.
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
Additionally some members of the MCS-51 family may have up to 128 bytes of additional,
 indirectly addressable,
 internal RAM memory (
\emph on
__idata
\emph default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

idata (mcs51,
 ds390 named address space)
\end_layout

\end_inset

).
 Furthermore,
 some chips may have some built in external memory (
\emph on
__xdata
\emph default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

xdata (mcs51,
 ds390 named address space)
\end_layout

\end_inset

) which should not be confused with the internal,
 directly addressable RAM memory (
\emph on
__data
\emph default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

data (mcs51,
 ds390 named address space)
\end_layout

\end_inset

).
 Sometimes this built in 
\emph on
__xdata
\emph default
 memory has to be activated before using it (you can probably find this information on the datasheet of the microcontroller your are using,
 see also section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:MCS51-Startup-Code"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset

Startup-Code).
\end_layout

\begin_layout Standard
Normally SDCC will only use the first bank
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
register bank (mcs51,
 ds390)
\end_layout

\end_inset

 of registers (register bank 0),
 but it is possible to specify that other banks of registers (keyword 
\emph on
__using
\emph default
 
\emph on

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

using (mcs51,
 ds390 register bank)
\end_layout

\end_inset


\emph default
) should be used for example in interrupt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

interrupt
\end_layout

\end_inset

 routines.
 By default,
 the compiler will place the stack after the last byte of allocated memory for variables.
 For example,
 if the first 2 banks of registers are used,
 and only four bytes are used for 
\emph on
__data
\emph default
 variables,
 it will position the base of the internal stack at address 20 (0x14).
 This implies that as the stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset

 grows,
 it will use up the remaining register banks,
 and the 16 bytes used by the 128 bit variables,
 and 80 bytes for general purpose use.
 If any bit variables are used,
 the 
\emph on
__data
\emph default
 variables will be placed in unused register banks and after the byte holding the last __bit variable.
 For example,
 if register banks 0 and 1 are used,
 and there are 9 bit variables (two bytes used),
 
\emph on
__data
\emph default
 variables will be placed starting from address 0x10 to 0x20 and continue at address 0x22.
 You can also use -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-data-loc
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-data-loc <Value>
\end_layout

\end_inset

 to specify the start address of the 
\emph on
__data
\emph default
 and -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-iram-size
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-iram-size <Value>
\end_layout

\end_inset

 to specify the size of the total internal RAM (
\emph on
__idata
\emph default
).
 
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
By default the 8051 linker will place the stack after the last byte of __(i)data variables.
 Option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-loc
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-loc <Value>
\end_layout

\end_inset

 allows you to specify the start of the stack,
 i.e.
 you could start it after any data in the general purpose area.
 If your microcontroller has additional indirectly addressable internal RAM (
\emph on
idata
\emph default
) you can place the stack on it.
 You may also need to use -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xdata-loc
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xdata-loc<Value>
\end_layout

\end_inset

 to set the start address of the external RAM (
\emph on
xdata
\emph default
) and -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xram-size
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xram-size <Value>
\end_layout

\end_inset

 to specify its size.
 Same goes for the code memory,
 using -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-code-loc
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-code-loc <Value>
\end_layout

\end_inset

 and -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-code-size
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-code-size <Value>
\end_layout

\end_inset

.
 If in doubt,
 don't specify any options and see if the resulting memory layout is appropriate,
 then you can adjust it.
\end_layout

\begin_layout Standard
The linker generates two files with memory allocation information.
 The first,
 with extension .map
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.map
\end_layout

\end_inset

 shows all the variables and segments.
 The second with extension .mem
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.mem
\end_layout

\end_inset

 shows the final memory layout.
 The linker will complain either if memory segments overlap,
 there is not enough memory,
 or there is not enough space for stack.
 If you get any linking warnings and/or errors related to stack or segments allocation,
 take a look at either the .map or .mem files to find out what the problem is.
 The .mem file may even suggest a solution to the problem.
\end_layout

\begin_layout Subsection
Z80/Z180/eZ80 intrinsic named address spaces
\end_layout

\begin_layout Subsubsection
__sfr
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sfr
\end_layout

\end_inset

 (in/out to 8-bit addresses)
\end_layout

\begin_layout Standard
The Z80
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80
\end_layout

\end_inset

 family has separate address spaces for memory and 
\emph on
i
\emph default
nput/
\emph on
o
\emph default
utput memory.
 I/O memory
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
I/O memory (Z80,
 Z180)
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80!I/O memory
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z180!I/O memory
\end_layout

\end_inset

 is accessed with special instructions,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__sfr __at(0x78) IoPort;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* define a var in I/O space at 78h called IoPort */ 
\end_layout

\begin_layout Standard
Writing 0x01 to this variable generates the assembly code:
\end_layout

\begin_layout Verse

\family typewriter
3E 01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ld a,#0x01
\begin_inset Newline newline
\end_inset

D3 78
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

out (_IoPort),a 
\end_layout

\begin_layout Subsubsection
__banked __sfr
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sfr
\end_layout

\end_inset

 (in/out to 16-bit addresses)
\end_layout

\begin_layout Standard
The keyword 
\emph on
__banked
\emph default
 is used to support 16 bit addresses in I/O memory e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__sfr __banked __at
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

at
\end_layout

\end_inset

(0x123) IoPort;
 
\end_layout

\begin_layout Standard
Writing 0x01 to this variable generates the assembly code:
\end_layout

\begin_layout Verse

\family typewriter
01 23 01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ld bc,#_IoPort
\begin_inset Newline newline
\end_inset

3E 01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ld a,#0x01
\begin_inset Newline newline
\end_inset

ED 79
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

out (c),a 
\end_layout

\begin_layout Subsubsection
__sfr
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sfr
\end_layout

\end_inset

 (in0/out0 to 8 bit addresses on Z180
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z180
\end_layout

\end_inset

/HD64180
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
HD64180 (see Z180)
\end_layout

\end_inset

)
\end_layout

\begin_layout Standard
The compiler option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-portmode
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z180!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-portmode
\end_layout

\end_inset

=180 (80) and a compiler #pragma
\begin_inset space ~
\end_inset

portmode
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z180!Pragmas!
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma portmode
\end_layout

\end_inset

 z180 (z80) is used to turn on (off) the Z180/HD64180 port addressing instructions 
\family typewriter
in0/out0
\family default
 instead of 
\family typewriter
in/out
\family default
.
 If you include the file z180.h this will be set automatically.
\end_layout

\begin_layout Subsection
SM83 intrinsic named address spaces
\end_layout

\begin_layout Subsubsection
__sfr
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sfr
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The keyword 
\emph on
__sfr
\emph default
 is an alternative way to access memory locations 0xff00 to 0xffff,
 which are typically used for memory-mapped I/O e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__sfr __at
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

at
\end_layout

\end_inset

(0xff01) IoPort;
 
\end_layout

\begin_layout Subsection
HC08/S08 intrinsic named address spaces
\end_layout

\begin_layout Subsubsection
__data
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

data (hc08 named address space)
\end_layout

\end_inset

 
\end_layout

\begin_layout Standard
Variables in the address space __data resides in the first 256 bytes of memory (the direct page).
 The HC08
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
HC08
\end_layout

\end_inset

 is most efficient at accessing variables (especially pointers) stored here.
\end_layout

\begin_layout Subsubsection
__xdata
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

xdata (hc08 named address space)
\end_layout

\end_inset

 
\end_layout

\begin_layout Standard
Variables in the address space__xdata can reside anywhere in memory.
 This is the default (generic address space).
\end_layout

\begin_layout Subsection
PDK14/PDK15 intrinsic named address spaces
\end_layout

\begin_layout Subsubsection
__sfr
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sfr
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The Padauk family has separate address spaces for memory and 
\emph on
i
\emph default
nput/
\emph on
o
\emph default
utput memory.
 I/O memory is accessed with special instructions,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__sfr __at(0x18) gpcc;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* define a var in I/O space at 18h called gpcc */
\end_layout

\begin_layout Subsubsection
__sfr16
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sfr16
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The Padauk family has a 16-bit timer accessed with special instructions.
\end_layout

\begin_layout Subsection
MOS6502 intrinsic named address spaces
\end_layout

\begin_layout Subsubsection
__zp/__data
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

data (mos6502 named address space)
\end_layout

\end_inset

 /__near
\end_layout

\begin_layout Standard
Variables in the address space __zp reside in the first 256 bytes of memory (the Page Zero).
 The MOS6502
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
MOS6502
\end_layout

\end_inset

 is most efficient at accessing variables stored here.
 Pointers can only be dereferenced directly if they reside in Page Zero.
 This is the default for the small memory model.
\end_layout

\begin_layout Subsubsection
__xdata
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

xdata (mos6502 named address space)
\end_layout

\end_inset

 /__far
\end_layout

\begin_layout Standard
Variables in the address space __xdata can reside anywhere in the 64K memory space.
 This is the default (for the large memory model).
\end_layout

\begin_layout Subsection
Non-intrinsic named address spaces
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
Non-intrinsic named address spaces
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC supports user-defined non-intrinsic named address spaces.
 So far SDCC only supports them for bank-switching.
 You need to have a function that switches to the desired memory bank and declare a corresponding named address space:
\end_layout

\begin_layout Verse

\family typewriter
void setb0(void);
 // The function that sets the currently active memory bank to b0
\begin_inset Newline newline
\end_inset

void setb1(void);
 // The function that sets the currently active memory bank to b1
\begin_inset Newline newline
\end_inset

__addressmod
\family default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

addressmod
\end_layout

\end_inset


\family typewriter
 setb0 spaceb0;
 // Declare a named address space called spaceb0 that uses setb0()
\begin_inset Newline newline
\end_inset

__addressmod setb1 spaceb1;
 // Declare a named address space called spaceb1 that uses setb1()
\begin_inset Newline newline
\end_inset

spaceb0 int x;
 // An int in address space spaceb0
\begin_inset Newline newline
\end_inset

spaceb1 int *y;
 // A pointer to an int in address space spaceb1
\begin_inset Newline newline
\end_inset

spaceb0 int *spaceb1 z;
 // A pointer in address space spaceb1 that points to an int in address space spaceb0
\end_layout

\begin_layout Standard
Non-intrinsic named address spaces for data in ROM are declared using the const keyword:
\end_layout

\begin_layout Verse

\family typewriter
void setb0(void);
 // The function that sets the currently active memory bank to b0
\begin_inset Newline newline
\end_inset

void setb1(void);
 // The function that sets the currently active memory bank to b1
\begin_inset Newline newline
\end_inset

__addressmod
\family default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

addressmod
\end_layout

\end_inset


\family typewriter
 setb0 const spaceb0;
 // Declare a named address space called spaceb0 that uses setb0() and resides in ROM
\begin_inset Newline newline
\end_inset

__addressmod setb1 spaceb1;
 // Declare a named address space called spaceb1 that uses setb1() and resides in RAM
\begin_inset Newline newline
\end_inset

const spaceb0 int x = 42;
 // An int in address space spaceb0
\begin_inset Newline newline
\end_inset

spaceb1 int *y;
 // A pointer to an int in address space spaceb1
\begin_inset Newline newline
\end_inset

const spaceb0 int *spaceb1 z;
 // A pointer in address space spaceb1 that points to a constant int in address space spaceb0
\end_layout

\begin_layout Standard
Variables in non-intrinsic named address spaces will be placed in areas of the same name (this can be used for the placement of named address spaces in memory by the linker).
\end_layout

\begin_layout Standard
SDCC will automatically insert calls to the corresponding function before accessing the variable.
 SDCC inserts the minimum possible number calls to the bank selection functions.
 See Philipp Klaus Krause,
 
\begin_inset Quotes sld
\end_inset

Optimal Placement of Bank Selection Instructions in Polynomial Time
\begin_inset Quotes srd
\end_inset

 for details on how this works.
\end_layout

\begin_layout Subsection
Absolute Addressing
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
Absolute addressing
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Data items can be assigned an absolute address with the 
\emph on
__at
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

at
\end_layout

\end_inset

 <address>
\emph default
 keyword (the address needs to be either a parenthesized constant expression or a constant),
 which can also be used in addition to a named address space,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__xdata unsigned int __at (0x7ffe) chksum;
\end_layout

\begin_layout Standard
In the above example the variable chksum will be located at 0x7ffe and 0x7fff of the external ram.
 The compiler does 
\emph on
not
\emph default
 reserve any space for variables declared in this way
\begin_inset Marginal
status collapsed

\begin_layout Plain Layout

\series bold
\begin_inset space ~
\end_inset

!
\end_layout

\end_inset

 (they are implemented with an equate in the assembler).
 Thus it is left to the programmer to make sure there are no overlaps with other variables that are declared without the absolute address.
 The assembler listing file (.lst
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.lst
\end_layout

\end_inset

) and the linker output files (.rst
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.rst
\end_layout

\end_inset

) and (.map
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.map
\end_layout

\end_inset

) are good places to look for such overlaps.
\end_layout

\begin_layout Standard
If however you provide an initializer
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Variable initialization
\end_layout

\end_inset

 actual memory allocation will take place and overlaps will be detected by the linker.
 E.g.:
\end_layout

\begin_layout Verse

\family typewriter
__code char __at (0x7ff0) Id[5] = 
\begin_inset Quotes sld
\end_inset

SDCC
\begin_inset Quotes srd
\end_inset

;
\end_layout

\begin_layout Standard
In the above example the variable Id will be located from 0x7ff0 to 0x7ff4 in code memory.
\end_layout

\begin_layout Standard
In case of memory mapped I/O devices the keyword 
\emph on
volatile
\emph default
 has to be used to tell the compiler that accesses might not be removed:
\end_layout

\begin_layout Verse

\family typewriter
volatile
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
volatile
\end_layout

\end_inset

 __xdata
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

xdata (mcs51,
 ds390 named address space)
\end_layout

\end_inset

 unsigned char __at
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

at
\end_layout

\end_inset

 (0x8000) PORTA_8255;
\end_layout

\begin_layout Standard
For some architectures (mcs51) array accesses are more efficient if an (xdata/far) array
\family typewriter
\size footnotesize

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Aligned array
\end_layout

\end_inset


\family default
\size default
 starts at a block (256 byte) boundary
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
block boundary
\end_layout

\end_inset

 (section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:A-Step-by Assembler Introduction"
nolink "false"

\end_inset

 has an example).
\begin_inset Newline newline
\end_inset

Absolute addresses can be specified for variables in all named address spaces,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
__bit
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

bit
\end_layout

\end_inset

 __at
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

at
\end_layout

\end_inset

 (0x02) bvar;
\end_layout

\begin_layout Standard
The above example will allocate the variable at offset 0x02 in the bit-addressable space.
 There is no real advantage to assigning absolute addresses to variables in this manner,
 unless you want strict control over all the variables allocated.
 One possible use would be to write hardware portable code.
 For example,
 if you have a routine that uses one or more of the microcontroller I/O pins,
 and such pins are different for two different hardwares,
 you can declare the I/O pins in your routine using:
\end_layout

\begin_layout Verse

\family typewriter
extern volatile
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
volatile
\end_layout

\end_inset

 __bit MOSI;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* master out,
 slave in */
\begin_inset Newline newline
\end_inset

extern volatile __bit MISO;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* master in,
 slave out */
\begin_inset Newline newline
\end_inset

extern volatile __bit MCLK;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* master clock */
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

/* Input and Output of a byte on a 3-wire serial bus.
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

If needed adapt polarity of clock,
 polarity of data and bit order
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset

*/
\begin_inset Newline newline
\end_inset

unsigned char spi_io(unsigned char out_byte)
\begin_inset Newline newline
\end_inset

{ 
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

unsigned char i=8;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

do { 
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

MOSI = out_byte & 0x80;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

out_byte <<= 1;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

MCLK = 1;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* __asm nop __endasm;
 */
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* for slow peripherals */
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

if(MISO)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

out_byte += 1;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

MCLK = 0;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

} while(--i);
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return out_byte;
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
Then,
 someplace in the code for the first hardware you would use
\end_layout

\begin_layout Verse

\family typewriter
__bit __at
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

at
\end_layout

\end_inset

 (0x80) MOSI;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* I/O port 0,
 bit 0 */
\begin_inset Newline newline
\end_inset

__bit __at (0x81) MISO;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* I/O port 0,
 bit 1 */
\begin_inset Newline newline
\end_inset

__bit __at (0x82) MCLK;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* I/O port 0,
 bit 2 */
\end_layout

\begin_layout Standard
Similarly,
 for the second hardware you would use
\end_layout

\begin_layout Verse

\family typewriter
__bit __at (0x83) MOSI;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* I/O port 0,
 bit 3 */
\begin_inset Newline newline
\end_inset

__bit __at (0x91) MISO;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* I/O port 1,
 bit 1 */
\begin_inset Newline newline
\end_inset

__bit
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

bit
\end_layout

\end_inset

 __at (0x92) MCLK;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* I/O port 1,
 bit 2 */
\end_layout

\begin_layout Standard
and you can use the same hardware dependent routine without changes,
 as for example in a library.
 This is somehow similar to sbit,
 but only one absolute address has to be specified in the whole project.
\end_layout

\begin_layout Subsection
__sdcc_external_startup
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sdcc
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

external
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

startup
\end_layout

\end_inset


\end_layout

\begin_layout Standard
When a function 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
unsigned char __sdcc_external_startup(void)
\end_layout

\end_inset

 is present,
 it is executed before both the initialization of static and global variables,
 as well as 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
main
\end_layout

\end_inset

.
 This allows to implement functionality that needs to be done early.
 For example:
 disabling a hardware watchdog that would otherwise bite during the time it takes to initialize global variables;
 setup or calibration of system/peripheral clocks;
 or,
 a memory check that needs to be done before any memory (other than the return address for 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
__sdcc_external_startup
\end_layout

\end_inset

 itself) is in use.
\end_layout

\begin_layout Standard
If this routine returns a non-zero value,
 the static and global variable initialization will be skipped and the function 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
main
\end_layout

\end_inset

 will be invoked.
 Otherwise static and global variables will be initialized before the function 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
main
\end_layout

\end_inset

 is invoked.
\end_layout

\begin_layout Standard
For mos6502,
 z80,
 z80n,
 z180,
 sm83,
 ez80_z80,
 tlcs90,
 r2k,
 r2ka,
 r3ka,
 when using a custom crt0,
 support depends on the custom crt0.
\end_layout

\begin_layout Subsection
Preserved register specification
\end_layout

\begin_layout Standard
SDCC allows to specify preserved registers in function declarations,
 to enable further optimizations on calls to functions implemented in assembler.
 Example for the Z80 architecture specifying that a function will preserve register pairs bc and iy:
\end_layout

\begin_layout Verse

\family typewriter
void f(void) __preserves_regs(b,
 c,
 iyl,
 iyh);
\end_layout

\begin_layout Subsection
Binary constants
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
Binary constants
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC supports the use of C23 binary constants,
 such as 0b01100010 when the compiler is invoked using 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--std-sdccxx
\end_layout

\end_inset

,
 even when the corresponding 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--std-cxx
\end_layout

\end_inset

,
 does not.
 Note:
 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
xx
\end_layout

\end_inset

 is a placeholder for the desired version of the C standard.
\end_layout

\begin_layout Subsection
Returning void
\end_layout

\begin_layout Standard
SDCC allows functions to return expressions of type void.
 This feature is only enabled when the compiler is invoked using 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--std-sdccxx
\end_layout

\end_inset

.
 Note:
 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
xx
\end_layout

\end_inset

 is a placeholder for the desired version of the C standard.
\end_layout

\begin_layout Subsection
Omitting promotion on arguments of vararg function (does not apply to pdk13,
 pdk14,
 pdk15)
\end_layout

\begin_layout Standard
Arguments to vararg functions are not promoted when explicitly cast.
 This feature is only enabled when the compiler is invoked using 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--std-sdccxx
\end_layout

\end_inset

.
 This breaks compability with the C standards,
 so linking code compiled with 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--std-sdccxx
\end_layout

\end_inset

 with code compiled using 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--std-cxx
\end_layout

\end_inset

 can result in failing programs when arguments to vararg functions are explicitly cast.
 Note:
 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
xx
\end_layout

\end_inset

 is a placeholder for the desired version of the C standard.
\end_layout

\begin_layout Section
Parameters
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Parameters
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
function parameter
\end_layout

\end_inset

 and Local Variables
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
local variables
\end_layout

\end_inset


\begin_inset CommandInset label
LatexCommand label
name "sec:Parameters-and-Local-Variables"

\end_inset


\end_layout

\begin_layout Standard
Automatic (local) variables and parameters to functions are placed on the stack for most targets.
 For MCS51/DS390/HC08/S08/MOS6502/PDK13/PDK14/PDK15 they can either be placed on the stack or in data-space.
 The default action of the compiler is to place these variables in the internal RAM (for small model) or external RAM (for medium or large model).
 This in fact makes them similar to 
\emph on
static
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
static
\end_layout

\end_inset


\emph default
 so by default functions are non-reentrant
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
reentrant
\end_layout

\end_inset

.
 
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

They can be placed on the stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset

 by using the 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\end_layout

\end_inset


\emph default
 option,
 by using 
\emph on
#pragma
\begin_inset space ~
\end_inset

stackauto
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma stackauto
\end_layout

\end_inset

 or by using the 
\emph on
__reentrant
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
reentrant
\end_layout

\end_inset


\emph default
 keyword in the function declaration,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
unsigned char foo(char i) __reentrant
\begin_inset Newline newline
\end_inset

{ 
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
 
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
Since stack space on 8051 and MOS6502 is limited,
 and accessing the stack is slow for the Padauk,
 the 
\emph on
__reentrant
\emph default
 keyword or the 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\emph default
 option should be used sparingly.
 Note that the 
\emph on
__reentrant
\emph default
 keyword just means that the parameters & local variables will be allocated to the stack,
 it 
\emph on
does not
\emph default
 mean that the function is register bank
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
register bank (mcs51,
 ds390)
\end_layout

\end_inset

 independent.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Local variables
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
local variables
\end_layout

\end_inset

 can be assigned intrinsic named address spaces and absolute
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Absolute addressing
\end_layout

\end_inset

 addresses,
 e.g.:
 
\end_layout

\begin_layout Verse

\family typewriter
unsigned char foo(__xdata int parm)
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__xdata unsigned char i;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__bit bvar;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__data unsigned char __at
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
at
\end_layout

\end_inset

 (0x31) j;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
 
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
In the above example the parameter
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
function parameter
\end_layout

\end_inset

 
\emph on
parm
\emph default
 and the variable 
\emph on
i
\emph default
 will be allocated in the external ram,
 
\emph on
bvar
\emph default
 in bit addressable space and 
\emph on
j
\emph default
 in internal ram.
 When compiled with 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\emph default
 or when a function is declared as 
\emph on
reentrant
\emph default
 this should only be done for static variables.
\end_layout

\begin_layout Standard
It is however allowed to use bit parameters in reentrant functions and also non-static local bit variables are supported.
 Efficient use is limited to 8 semi-bitregisters in bit space.
 They are pushed and popped to stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset

 as a single byte just like the normal registers.
\end_layout

\begin_layout Section
Overlaying
\begin_inset CommandInset label
LatexCommand label
name "subsec:Overlaying"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Overlaying
\end_layout

\end_inset


\end_layout

\begin_layout Standard
For non-reentrant
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
reentrant
\end_layout

\end_inset

 functions SDCC will try to reduce internal ram space usage by overlaying parameters and local variables of a function (if possible).
 Parameters and local variables
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
local variables
\end_layout

\end_inset

 of a function will be allocated to an overlayable segment if the function has 
\emph on
no other function calls and the function is non-reentrant and the memory model
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Memory model
\end_layout

\end_inset

 is small.

\emph default
 If an explicit intrinsic named address space
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
intrinsic named address space
\end_layout

\end_inset

 is specified for a local variable,
 it will NOT be overlaid.
\end_layout

\begin_layout Standard
Note that the compiler (not the linkage editor) makes the decision for overlaying the data items.
 Functions that are called from an interrupt service routine
\begin_inset Marginal
status collapsed

\begin_layout Plain Layout

\series bold
!
\end_layout

\end_inset

 should be preceded by a #pragma
\begin_inset space ~
\end_inset

nooverlay
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma nooverlay
\end_layout

\end_inset

 if they are not reentrant.
\end_layout

\begin_layout Standard
Also note that the compiler does not do any processing of inline assembler code,
 so the compiler might incorrectly assign local variables and parameters of a function into the overlay segment if the inline assembler code calls other c-functions that might use the overlay.
 In that case the #pragma
\begin_inset space ~
\end_inset

nooverlay should be used.
\end_layout

\begin_layout Standard
Parameters and local variables of functions that contain 16 or 32 bit multiplication
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Multiplication
\end_layout

\end_inset

 or division
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Division
\end_layout

\end_inset

 will NOT be overlaid since these are implemented using external functions,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
#pragma save
\begin_inset Newline newline
\end_inset

#pragma nooverlay
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma nooverlay
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset

void set_error(unsigned char errcd)
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

P3 = errcd;
\begin_inset Newline newline
\end_inset

} 
\begin_inset Newline newline
\end_inset

#pragma restore
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void some_isr () __interrupt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset

 (2)
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

set_error(10);
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
In the above example the parameter 
\emph on
errcd
\emph default
 for the function 
\emph on
set_error
\emph default
 would be assigned to the overlayable segment if the #pragma
\begin_inset space ~
\end_inset

nooverlay was not present,
 this could cause unpredictable runtime behaviour when called from an interrupt service routine.
 The #pragma
\begin_inset space ~
\end_inset

nooverlay ensures that the parameters and local variables for the function are NOT overlaid.
\end_layout

\begin_layout Section
Interrupt Service Routines
\begin_inset CommandInset label
LatexCommand label
name "subsec:Interrupt-Service-Routines"

\end_inset


\end_layout

\begin_layout Subsection
General Information
\end_layout

\begin_layout Standard
SDCC allows 
\emph on
i
\emph default
nterrupt 
\emph on
s
\emph default
ervice 
\emph on
r
\emph default
outines to be coded in C,
 with some extended keywords.
\end_layout

\begin_layout Verse

\family typewriter
void timer_isr (void) __interrupt (1) __using (1)
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
The optional number following the 
\emph on
__interrupt
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

interrupt
\end_layout

\end_inset


\emph default
 keyword is the interrupt number this routine will service.
 When present,
 the compiler will insert a call to this routine in the interrupt vector table
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt vector table
\end_layout

\end_inset

 for the interrupt number specified.
 If you have multiple source files in your project,
 interrupt service routines can be present in any of them,
 but a prototype of the isr MUST be present or included in the file that contains the function 
\emph on
main
\emph default
.
 The optional (8051 specific) keyword 
\emph on
__using
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

using (mcs51,
 ds390 register bank)
\end_layout

\end_inset


\emph default
 can be used to tell the compiler to use the specified register bank when generating code for this function.
\begin_inset Newline newline
\end_inset

Interrupt service routines open the door for some very interesting bugs:
\end_layout

\begin_layout Subsubsection
\begin_inset CommandInset label
LatexCommand label
name "subsec:Common-interrupt-pitfall-volatile"

\end_inset

Common interrupt pitfall:
 variable not declared 
\emph on
volatile
\end_layout

\begin_layout Standard
If an interrupt service routine changes variables which are accessed by other functions these variables have to be declared 
\emph on
volatile
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
volatile
\end_layout

\end_inset

.
 See 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://en.wikipedia.org/wiki/Volatile_variable
\end_layout

\end_inset

.
\end_layout

\begin_layout Subsubsection
\begin_inset CommandInset label
LatexCommand label
name "subsec:Common-interrupt-pitfall-non-atomic"

\end_inset

Common interrupt pitfall:
 
\emph on
non-atomic access
\end_layout

\begin_layout Standard
If the access to these variables is not 
\emph on
atomic
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
atomic
\end_layout

\end_inset


\emph default
 (i.e.
 the processor needs more than one instruction for the access and could be interrupted while accessing the variable) the interrupt must be disabled during the access to avoid inconsistent data.
 
\begin_inset Newline newline
\end_inset

Access to 16 or 32 bit variables is obviously not atomic on 8 bit CPUs and should be protected by disabling interrupts.
 You're not automatically on the safe side if you use 8 bit variables though.
 We need an example here:
 f.e.
 on the 8051 the harmless looking 
\begin_inset Quotes srd
\end_inset


\family typewriter
flags
\begin_inset space ~
\end_inset

|=
\begin_inset space ~
\end_inset

0x80;
\family default

\begin_inset Quotes sld
\end_inset

 is not atomic if 
\family typewriter
flags
\family default
 resides in xdata.
 Setting 
\begin_inset Quotes srd
\end_inset


\family typewriter
flags
\begin_inset space ~
\end_inset

|=
\begin_inset space ~
\end_inset

0x40;
\family default

\begin_inset Quotes sld
\end_inset

 from within an interrupt routine might get lost if the interrupt occurs at the wrong time.
 
\begin_inset Quotes sld
\end_inset


\family typewriter
counter
\begin_inset space ~
\end_inset

+=
\begin_inset space ~
\end_inset

8;
\family default

\begin_inset Quotes srd
\end_inset

 is not atomic on the 8051 even if 
\family typewriter
counter
\family default
 is located in data memory.
\begin_inset Newline newline
\end_inset

Bugs like these are hard to reproduce and can cause a lot of trouble.
 
\end_layout

\begin_layout Subsubsection
\begin_inset CommandInset label
LatexCommand label
name "subsec:Common-interrupt-pitfall-stack-overflow"

\end_inset

Common interrupt pitfall:
 
\emph on
stack overflow
\end_layout

\begin_layout Standard
The return address and the registers used in the interrupt service routine are saved on the stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset

 so there must be sufficient stack space.
 If there isn't variables or registers (or even the return address itself) will be corrupted.
 This 
\emph on
stack overflow
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack overflow
\end_layout

\end_inset

 is most likely to happen if the interrupt occurs during the 
\begin_inset Quotes sld
\end_inset

deepest
\begin_inset Quotes srd
\end_inset

 subroutine when the stack is already in use for f.e.
 many return addresses.
\end_layout

\begin_layout Subsubsection
\begin_inset CommandInset label
LatexCommand label
name "subsec:Common-interrupt-pitfall-non-reentrant"

\end_inset

Common interrupt pitfall:
 
\emph on
use of non-reentrant functions
\end_layout

\begin_layout Standard
A special note here,
 integer multiplicative operators and floating-point
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Floating point support
\end_layout

\end_inset

 operations might be implemented using external support routines,
 depending on the target architecture.
 If an interrupt service routine needs to do any of these operations on a target where functions are non-reentrant by default,
 then the support routines (as mentioned in a following section) will have to be recompiled using the 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\end_layout

\end_inset


\emph default
 option and the source file will need to be compiled using the 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-int-long-reent
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-int-long-reent
\end_layout

\end_inset

 compiler option.
 
\begin_inset Newline newline
\end_inset

Note,
 the type promotion
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
type promotion
\end_layout

\end_inset

 required by ANSI C can cause 16 bit routines to be used
\begin_inset Marginal
status collapsed

\begin_layout Plain Layout

\series bold
\begin_inset space ~
\end_inset

!
\end_layout

\end_inset

 without the programmer being aware of it.
 See f.e.
 the cast 
\family typewriter
\series bold
(unsigned char)(tail-1)
\family default
\series default
 
\series bold
within the if clause in section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:A-Step-by Assembler Introduction"
nolink "false"

\end_inset

.
\end_layout

\begin_layout Standard
Calling other functions from an interrupt service routine on a target where functions are non-reentrant by default is not recommended,
 avoid it if possible.
 Note that when some function is called from an interrupt service routine it should be preceded by a #pragma
\begin_inset space ~
\end_inset

nooverlay
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma nooverlay
\end_layout

\end_inset

 if it is not reentrant.
 Furthermore non-reentrant functions should not be called from the main program while the interrupt service routine might be active.
 They also must not be called from low priority interrupt service routines while a high priority interrupt service routine might be active.
 You could use semaphores or make the function 
\emph on
critical
\emph default
 if all parameters are passed in registers.
\begin_inset Newline newline
\end_inset

 Also see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Overlaying"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset

about Overlaying and section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Functions-using-private-banks"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset

about Functions using private register banks.
\end_layout

\begin_layout Subsection
MCS51/DS390 Interrupt Service Routines
\end_layout

\begin_layout Standard
Interrupt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset

 numbers and the corresponding address & descriptions for the Standard 8051/8052 are listed below.
 SDCC will automatically adjust the 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt vector table
\end_layout

\end_inset

 to the maximum interrupt number specified.
\begin_inset Newline newline
\end_inset


\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="9" columns="3">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0in">
<column alignment="left" valignment="top" width="0in">
<column alignment="left" valignment="top" width="0in">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interrupt #
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Description
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Vector Address
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
External 0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0x0003
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Timer 0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0x000b
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
External 1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0x0013
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Timer 1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0x001b
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
4
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Serial
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0x0023
\end_layout

\end_inset
</cell>
</row>
<row>
<cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
5
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Timer 2 (8052)
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0x002b
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
...
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
...
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
n
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0x0003 + 8*n
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
If the interrupt service routine is defined without 
\emph on
__using
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
using (mcs51,
 ds390 register bank)
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

using (mcs51,
 ds390 register bank)
\end_layout

\end_inset


\emph default
 a register bank or with register bank 0 (
\emph on
__using
\emph default
 (0)),
 the compiler will save the registers used by itself on the stack upon entry and restore them at exit,
 however if such an interrupt service routine calls another function then the entire register bank will be saved on the stack.
 This scheme may be advantageous for small interrupt service routines which have low register usage.
\end_layout

\begin_layout Standard
If the interrupt service routine is defined to be using a specific register bank then only 
\emph on
a,
 b,
 dptr
\emph default
 & psw are saved and restored,
 if such an interrupt service routine calls another function (using another register bank) then the entire register bank of the called function will be saved on the stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset

.
 This scheme is recommended for larger interrupt service routines.
\end_layout

\begin_layout Subsection
HC08
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
HC08
\end_layout

\end_inset

 Interrupt Service Routines
\end_layout

\begin_layout Standard
Since the number of interrupts
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
HC08!interrupt
\end_layout

\end_inset

 available is chip specific and the interrupt vector table always ends at the last byte of memory,
 the interrupt numbers corresponds to the interrupt vectors in reverse order of address.
 For example,
 interrupt 1 will use the interrupt vector at 0xfffc,
 interrupt 2 will use the interrupt vector at 0xfffa,
 and so on.
 However,
 interrupt 0 (the reset vector at 0xfffe) is not redefinable in this way;
 instead see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:MCS51-Startup-Code"
nolink "false"

\end_inset

 for details on customizing startup.
\end_layout

\begin_layout Subsection
Z80,
 Z180 and eZ80 Interrupt Service Routines
\end_layout

\begin_layout Standard
The Z80
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80
\end_layout

\end_inset

 uses several different methods for determining the correct interrupt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80!interrupt
\end_layout

\end_inset

 vector depending on the hardware implementation.
 Therefore,
 SDCC does not attempt to generate an interrupt vector table.
\end_layout

\begin_layout Standard
By default,
 SDCC generates code for a maskable interrupt,
 which uses a RETI instruction to return from the interrupt.
 To write an interrupt handler for the non-maskable interrupt,
 which needs a RETN instruction instead,
 leave out the interrupt number:
\end_layout

\begin_layout Verse

\family typewriter
void nmi_isr (void) __critical __interrupt
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
Since interrupts on the Z80 and Z180 are level-triggered (except for the NMI),
 interruptible interrupt handlers should only be used where hardware acknowledge is available.
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="4" columns="3">
<features tabularvalignment="middle">
<column alignment="left" valignment="top">
<column alignment="left" valignment="top">
<column alignment="left" valignment="top" width="30text%">
<row>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Type
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Syntax
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Behaviour
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interruptible interrupt handler
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
void f(void) __interrupt
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interrupt handler can be interrupted by further interrupts
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Non-interruptible interrupt handler
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
void f(void) __critical __interrupt(0)
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interrupt handler can be interrupted by NMI only
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
NMI handler
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
void f(void) __critical __interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interrupt handler can be interrupted by NMI only
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Subsection
Rabbit 2000,
 3000 and 3000A Interrupt Service Routines
\end_layout

\begin_layout Standard
SDCC does not attempt to generate an interrupt vector table.
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="3">
<features tabularvalignment="middle">
<column alignment="left" valignment="top">
<column alignment="left" valignment="top">
<column alignment="left" valignment="top" width="30text%">
<row>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Type
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Syntax
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Behaviour
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interruptible interrupt handler
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
void f(void) __interrupt
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interrupt handler can be interrupted by further interrupts of same priority
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Non-interruptible interrupt handler
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
void f(void) __critical __interrupt(0)
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interrupt handler can be interrupted by interrupts of higher priority only
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Subsection
SM83 and TLCS-90 Interrupt Service Routines
\end_layout

\begin_layout Standard
SDCC does not attempt to generate an interrupt vector table.
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="3">
<features tabularvalignment="middle">
<column alignment="left" valignment="top">
<column alignment="left" valignment="top">
<column alignment="left" valignment="top" width="30text%">
<row>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Type
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Syntax
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Behaviour
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interruptible interrupt handler
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
void f(void) __interrupt
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interrupt handler can be interrupted by further interrupts
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Non-interruptible interrupt handler
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
void f(void) __critical __interrupt(0)
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interrupt handler cannot be interrupted by further interrupts
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Subsection
STM8 Interrupt Service Routines
\end_layout

\begin_layout Standard
The STM8 interrupt table contains 31 entries:
 Reset (used by SDCC for program startup),
 trap and user interrupts 0 to 29.
 Where the keyword 
\emph on
__interrupt
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset


\emph default
 is used for normal user interrupts,
 the 
\emph on
__trap
\emph default
 keyword is used for the trap handler:
\end_layout

\begin_layout Verse

\family typewriter
void handler (void) __trap
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Section
Enabling and Disabling Interrupts
\end_layout

\begin_layout Subsection
Critical Functions and Critical Statements
\end_layout

\begin_layout Standard
A special keyword may be associated with a block or a function declaring it as 
\emph on
__critical
\emph default
.
 SDCC will generate code to disable all interrupts
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset

 upon entry to a critical function and restore the interrupt enable to the previous state before returning (for architectures where there is no efficient way to do so (sm83,
 tlcs90,
 stm8),
 interrupts will be unconditionally enabled instead).
 Nesting critical functions will need one additional byte on the stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset

 for each call.
\end_layout

\begin_layout Verse

\family typewriter
int foo () __critical
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
critical
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

critical
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
The critical attribute maybe used with other attributes like 
\emph on
reentrant.
\emph default

\begin_inset Newline newline
\end_inset

The keyword 
\emph on
__critical
\emph default
 may also be used to disable interrupts more locally:
\end_layout

\begin_layout Verse

\family typewriter
__critical{ i++;
 }
\end_layout

\begin_layout Standard
More than one statement could have been included in the block.
\end_layout

\begin_layout Subsection
Enabling and Disabling Interrupts directly
\end_layout

\begin_layout Standard
Interrupts
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset

 can also be disabled and enabled directly (8051):
\end_layout

\begin_layout Verse

\family typewriter
EA = 0;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

or:
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

EA_SAVE = EA;
\end_layout

\begin_layout Verse

\family typewriter
...
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

EA = 0;
\end_layout

\begin_layout Verse

\family typewriter
EA = 1;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset

...
\end_layout

\begin_layout Verse

\family typewriter
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

EA = EA_SAVE;
\end_layout

\begin_layout Standard
On other architectures which have separate opcodes for enabling and disabling interrupts you might want to make use of defines with inline assembly
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Assembler routines
\end_layout

\end_inset

 (HC08
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
HC08!interrupt
\end_layout

\end_inset

):
\end_layout

\begin_layout Verse

\family typewriter
#define CLI __asm
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

asm
\end_layout

\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

cli
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__endasm
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

endasm
\end_layout

\end_inset

;
 
\end_layout

\begin_layout Verse

\family typewriter
#define SEI __asm
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sei
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__endasm;
 
\end_layout

\begin_layout Verse
or for SDCC version 3.2.0 or newer:
\end_layout

\begin_layout Verse

\family typewriter
#define CLI __asm__ (
\begin_inset Quotes sld
\end_inset

cli
\begin_inset Quotes srd
\end_inset

);
 
\end_layout

\begin_layout Verse

\family typewriter
#define SEI __asm__ (
\begin_inset Quotes sld
\end_inset

sei
\begin_inset Quotes srd
\end_inset

);
 
\end_layout

\begin_layout Standard
Note:
 it is sometimes sufficient to disable only a specific interrupt source like f.e.
 a timer or serial interrupt by manipulating an 
\emph on
interrupt mask
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt mask
\end_layout

\end_inset


\emph default
 register.
 
\end_layout

\begin_layout Standard
Usually the time during which interrupts are disabled should be kept as short as possible.
 This minimizes both 
\emph on
interrupt latency
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt latency
\end_layout

\end_inset

 (the time between the occurrence of the interrupt and the execution of the first code in the interrupt routine) and 
\emph on
interrupt jitter
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt jitter
\end_layout

\end_inset

 (the difference between the shortest and the longest interrupt latency).
 These really are something different,
 f.e.
 a serial interrupt has to be served before its buffer overruns so it cares for the maximum interrupt latency,
 whereas it does not care about jitter.
 On a loudspeaker driven via a digital to analog converter which is fed by an interrupt a latency of a few milliseconds might be tolerable,
 whereas a much smaller jitter will be very audible.
\end_layout

\begin_layout Standard
You can re-enable interrupts within an interrupt routine and on some architectures you can make use of two (or more) levels of 
\emph on
interrupt priorities
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt priority
\end_layout

\end_inset

.
 On some architectures which don't support interrupt priorities these can be implemented by manipulating the interrupt mask and re-enabling interrupts within the interrupt routine.
 Check there is sufficient space on the stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset

 and don't add complexity unless you have to.
 
\end_layout

\begin_layout Subsection
Semaphore
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
semaphore
\end_layout

\end_inset

 locking (mcs51/ds390)
\end_layout

\begin_layout Standard
Some architectures (mcs51/ds390) have an atomic
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
atomic
\end_layout

\end_inset

 bit test and clear instruction.
 These type of instructions are typically used in preemptive multitasking systems,
 where a routine f.e.
 claims the use of a data structure ('acquires a lock
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
lock
\end_layout

\end_inset

 on it'),
 makes some modifications and then releases the lock when the data structure is consistent again.
 The instruction may also be used if interrupt and non-interrupt code have to compete for a resource.
 With the atomic bit test and clear instruction interrupts
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset

 don't have to be disabled for the locking operation.
 
\end_layout

\begin_layout Standard
SDCC generates this instruction if the source follows this pattern:
\end_layout

\begin_layout Verse

\family typewriter
volatile
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
volatile
\end_layout

\end_inset

 bit resource_is_free;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

if (resource_is_free)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

resource_is_free=0;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

resource_is_free=1;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

} 
\end_layout

\begin_layout Standard
Note,
 mcs51 and ds390 support only an atomic
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
atomic
\end_layout

\end_inset

 bit test and 
\emph on
clear
\emph default
 instruction (as opposed to atomic bit test and 
\emph on
set).
\end_layout

\begin_layout Section
Functions using private register banks
\begin_inset CommandInset label
LatexCommand label
name "subsec:Functions-using-private-banks"

\end_inset

 (mcs51/ds390)
\end_layout

\begin_layout Standard
Some architectures have support for quickly changing register sets.
 SDCC supports this feature with the 
\emph on
__using
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
using (mcs51,
 ds390 register bank)
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

using (mcs51,
 ds390 register bank)
\end_layout

\end_inset


\emph default
 attribute (which tells the compiler to use a register bank
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
register bank (mcs51,
 ds390)
\end_layout

\end_inset

 other than the default bank zero).
 It should only be applied to 
\emph on
interrupt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset


\emph default
 functions (see footnote below).
 This will in most circumstances make the generated ISR code more efficient since it will not have to save registers on the stack.
\end_layout

\begin_layout Standard
The 
\emph on
__using
\emph default
 attribute will have no effect on the generated code for a 
\emph on
non-interrupt
\emph default
 function (but may occasionally be useful anyway
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
possible exception:
 if a function is called ONLY from 'interrupt' functions using a particular bank,
 it can be declared with the same 'using' attribute as the calling 'interrupt' functions.
 For instance,
 if you have several ISRs using bank one,
 and all of them call memcpy(),
 it might make sense to create a specialized version of memcpy() 'using 1',
 since this would prevent the ISR from having to save bank zero to the stack on entry and switch to bank zero before calling the function
\end_layout

\end_inset

).
\begin_inset Newline newline
\end_inset


\emph on
(pending:
 Note,
 nowadays the
\emph default
 __using 
\emph on
attribute has an effect on
\emph default
 
\emph on
the generated code for a
\emph default
 non-interrupt 
\emph on
function
\emph default
.
\emph on
)
\end_layout

\begin_layout Standard
An 
\emph on
interrupt
\emph default
 function using a non-zero bank will assume that it can trash that register bank,
 and will not save it.
 Since high-priority interrupts
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupts
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt priority
\end_layout

\end_inset

 can interrupt low-priority ones on the 8051 and friends,
 this means that if a high-priority ISR 
\emph on
using
\emph default
 a particular bank occurs while processing a low-priority ISR 
\emph on
using
\emph default
 the same bank,
 terrible and bad things can happen.
 To prevent this,
 no single register bank should be 
\emph on
used
\emph default
 by both a high priority and a low priority ISR.
 This is probably most easily done by having all high priority ISRs use one bank and all low priority ISRs use another.
 If you have an ISR which can change priority at runtime,
 you're on your own:
 I suggest using the default bank zero and taking the small performance hit.
\end_layout

\begin_layout Standard
It is most efficient if your ISR calls no other functions.
 If your ISR must call other functions,
 it is most efficient if those functions use the same bank as the ISR (see note 1 below);
 the next best is if the called functions use bank zero.
 It is very inefficient to call a function using a different,
 non-zero bank from an ISR.
 
\end_layout

\begin_layout Section
Inline Assembler Code
\begin_inset CommandInset label
LatexCommand label
name "sec:Inline-Assembler-Code"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Assembler routines
\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Inline Assembler Code Formats
\end_layout

\begin_layout Standard
SDCC supports two formats for inline assembler code definition:
\end_layout

\begin_layout Subsubsection
Old __asm ...
 __endasm;
 Format
\end_layout

\begin_layout Standard
Most of inline assembler code examples in this manual use the old inline assembler code format,
 but the new format could be used equivalently.
\end_layout

\begin_layout Standard
Example:
\end_layout

\begin_layout Verse

\family typewriter
__asm
\family default

\begin_inset Newline newline
\end_inset


\family typewriter

\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 This is a comment
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

label:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

nop
\begin_inset Newline newline
\end_inset

__endasm;
\end_layout

\begin_layout Standard
Note:
 As of SDCC 4.2.9,
 assembler comments occurring in this type of inline assembler block are affected by macro expansion.
\end_layout

\begin_layout Subsubsection
New __asm__ (
\begin_inset Quotes sld
\end_inset

inline_assembler_code
\begin_inset Quotes srd
\end_inset

) Format
\end_layout

\begin_layout Standard
The __asm__ inline assembler code format was introduced in SDCC version 3.2.0.
 Its main advantage is that it is compatible with all standard compliant C preprocessors.
\end_layout

\begin_layout Standard
Example:
\end_layout

\begin_layout Verse

\family typewriter
__asm__ (
\begin_inset Quotes sld
\end_inset

;
 This is a comment
\backslash
nlabel:
\backslash
n
\backslash
tnop
\begin_inset Quotes srd
\end_inset

);
\end_layout

\begin_layout Standard
\begin_inset Separator plain
\end_inset


\end_layout

\begin_layout Standard
Or for better readability:
\end_layout

\begin_layout Verse

\family typewriter
__asm__ (
\end_layout

\begin_layout Verse

\family typewriter
\begin_inset Quotes sld
\end_inset

;
 This is a comment
\backslash
n
\begin_inset Quotes srd
\end_inset


\end_layout

\begin_layout Verse

\family typewriter
\begin_inset Quotes sld
\end_inset

label:
\backslash
n
\begin_inset Quotes srd
\end_inset


\end_layout

\begin_layout Verse

\family typewriter
\begin_inset Quotes sld
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

nop
\begin_inset Quotes srd
\end_inset


\end_layout

\begin_layout Verse

\family typewriter
);
\end_layout

\begin_layout Subsection
A Step by Step Introduction
\begin_inset CommandInset label
LatexCommand label
name "subsec:A-Step-by Assembler Introduction"

\end_inset


\end_layout

\begin_layout Standard
Starting from a small snippet of c-code this example shows for the MCS51 how to use inline assembly,
 access variables,
 a function parameter and an array in xdata memory.
 The example uses an MCS51 here but is easily adapted for other architectures.
 This is a buffer routine which should be optimized:
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
unsigned char __far
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

far (named address space)
\end_layout

\end_inset

 __at
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

at
\end_layout

\end_inset

(0x7f00) buf[0x100];
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Aligned array
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset

unsigned char head,
 tail;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* if interrupts
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset

 are involved see
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Common-interrupt-pitfall-volatile"
nolink "false"

\end_inset

 about
\family default
 
\family typewriter
\series bold
volatile
\family default
\series default
 
\family typewriter
*/
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void to_buffer( unsigned char c ) 
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

if( head != (unsigned char)(tail-1) )
\begin_inset space ~
\end_inset

/* cast
\family default
 
\family typewriter
\series bold
needed
\family default
\series default
 
\family typewriter
to avoid promotion
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
promotion to signed int
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
type promotion
\end_layout

\end_inset

 to integer */
\begin_inset Marginal
status collapsed

\begin_layout Plain Layout

\series bold
\begin_inset space ~
\end_inset

!
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

buf[ head++ ] = c;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* access to a 256 byte aligned array */
\begin_inset Newline newline
\end_inset

} 
\end_layout

\begin_layout Standard
If the code snippet (assume it is saved in buffer.c) is compiled with SDCC then a corresponding buffer.asm file is generated.
 We define a new function 
\family typewriter
to_buffer_asm()
\family default
 in file buffer.c in which we cut and paste the generated code,
 removing unwanted comments and some ':'.
 Then add 
\begin_inset Quotes sld
\end_inset


\series bold
__asm
\series default

\begin_inset Quotes srd
\end_inset

 and 
\begin_inset Quotes sld
\end_inset


\series bold
__endasm;
\series default

\begin_inset Quotes srd
\end_inset


\begin_inset Foot
status collapsed

\begin_layout Plain Layout
Note,
 that the single underscore form (_asm and _endasm) are not C99 compatible,
 and for C99 compatibility,
 the double-underscore form (__asm and __endasm) has to be used.
 The latter is also used in the library functions.
\end_layout

\end_inset

 to the beginning and the end of the function body:
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
/* With a cut and paste from the .asm file,
 we have something to start with.
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

The function is not yet OK!
 (registers aren't saved) */ 
\begin_inset Newline newline
\end_inset

void to_buffer_asm( unsigned char c ) 
\begin_inset Newline newline
\end_inset

{ 
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__asm
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

asm
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

r2,dpl
\begin_inset Newline newline
\end_inset

;buffer.c if( head != (unsigned char)(tail-1) ) 
\begin_inset space ~
\end_inset

/* cast
\family default
 
\family typewriter
\series bold
needed
\family default
\series default
 
\family typewriter
to avoid promotion
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
promotion to signed int
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
type promotion
\end_layout

\end_inset

 to integer */
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,_tail
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dec
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

r3,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,_head
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

cjne a,ar3,00106$
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ret
\begin_inset Newline newline
\end_inset

00106$:
\begin_inset Newline newline
\end_inset

;buffer.c buf[ head++ ] = c;
 /* access to a 256 byte aligned array */
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Aligned array
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

r3,_head
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

_head
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dpl,r3
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dph,#(_buf >> 8)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,r2
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

movx @dptr,a
\begin_inset Newline newline
\end_inset

00103$:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ret
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__endasm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

endasm
\end_layout

\end_inset

;
\begin_inset Newline newline
\end_inset

} 
\end_layout

\begin_layout Standard
The new file buffer.c should compile with only one warning about the unreferenced function argument 'c'.
 Now we hand-optimize the assembly code and insert an #define USE_ASSEMBLY (1) and finally have:
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
unsigned char __far __at(0x7f00) buf[0x100];
\begin_inset Newline newline
\end_inset

unsigned char head,
 tail;
\begin_inset Newline newline
\end_inset

#define USE_ASSEMBLY (1)
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

#if !USE_ASSEMBLY
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void to_buffer( unsigned char c )
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

if( head != (unsigned char)(tail-1) )
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

buf[ head++ ] = c;
\begin_inset Newline newline
\end_inset

}
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

#else
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void to_buffer( unsigned char c )
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

c;
 // to avoid warning:
 unreferenced function argument
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__asm
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

asm
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 save used registers here.
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 If we were still using r2,r3 we would have to push them here.
\begin_inset Newline newline
\end_inset

;
 if( head != (unsigned char)(tail-1) )
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset

 a,_tail
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dec
\begin_inset space ~
\end_inset

 a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

xrl
\begin_inset space ~
\end_inset

 a,_head
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 we could do an ANL a,#0x0f here to use a smaller buffer (see below)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

jz
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 t_b_end$
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
\begin_inset Newline newline
\end_inset

;
 buf[ head++ ] = c;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset

 a,dpl 
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 dpl holds lower byte of function argument
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset

 dpl,_head 
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 buf is 0x100 byte aligned so head can be used directly
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset

 dph,#(_buf>>8)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

movx @dptr,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc 
\begin_inset space ~
\end_inset

_head
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 we could do an ANL _head,#0x0f here to use a smaller buffer (see above)
\begin_inset Newline newline
\end_inset

t_b_end$:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 restore used registers here
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__endasm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

endasm
\end_layout

\end_inset

;
\begin_inset Newline newline
\end_inset

}
\begin_inset Newline newline
\end_inset

#endif
\end_layout

\begin_layout Standard
The inline assembler code can contain any valid code understood by the assembler,
 this includes any assembler directives and comment lines.
 The assembler does not like some characters like ':' or ''' in comments.
 You'll find an 100+ pages assembler manual in sdcc/sdas/doc/asmlnk.txt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sdas (sdasgb,
 sdas6808,
 sdas8051,
 sdasz80)
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Assembler documentation
\end_layout

\end_inset

 or online at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://svn.code.sf.net/p/sdcc/code/trunk/sdcc/sdas/doc/asmlnk.txt
\end_layout

\end_inset

.
\end_layout

\begin_layout Standard
The compiler does not do any validation of the code within the 
\family typewriter
__asm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

asm
\end_layout

\end_inset

 ...
 __endasm
\size footnotesize

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

endasm
\end_layout

\end_inset


\size default
;

\family default
 keyword pair.
 Specifically it will not know which registers are used and thus register pushing/popping
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
push/pop
\end_layout

\end_inset

 has to be done manually.
 
\end_layout

\begin_layout Standard
It is required that each assembly instruction be placed on a separate line.
 This is also recommended for labels (as the example shows).
 This is especially important to note when the inline assembler is placed in a C preprocessor macro as the preprocessor will normally put all replacing code on a single line.
 Only when the macro has each assembly instruction on a single line that ends with a line continuation character will it be placed as separate lines in the resulting .asm file.
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
#define
\begin_inset space ~
\end_inset

DELAY
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\backslash

\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__asm
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\backslash

\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

nop
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\backslash

\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

nop
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\backslash

\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__endasm
\end_layout

\begin_layout Standard
When the -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\emph on
peep-asm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-asm
\end_layout

\end_inset


\emph default
 command line option is used,
 the inline assembler code will be passed through the peephole optimizer
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Peephole optimizer
\end_layout

\end_inset

.
 There are only a few (if any) cases where this option makes sense,
 it might cause some unexpected changes in the inline assembler code.
 Please go through the peephole optimizer rules defined in file 
\emph on
peeph.def
\emph default
 before using this option.
\end_layout

\begin_layout Subsection
Naked Functions
\begin_inset CommandInset label
LatexCommand label
name "subsec:Naked-Functions"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Naked functions
\end_layout

\end_inset


\end_layout

\begin_layout Standard
A special keyword may be associated with a function declaring it as 
\emph on
__naked
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

naked
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

naked
\end_layout

\end_inset

.

\emph default
 The 
\emph on
_naked
\emph default
 function modifier attribute prevents the compiler from generating prologue
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
function prologue
\end_layout

\end_inset

 and epilogue
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
function epilogue
\end_layout

\end_inset

 code for that function.
 This means that the user is entirely responsible for such things as saving any registers that may need to be preserved,
 selecting the proper register bank,
 generating the 
\emph on
return
\emph default
 instruction at the end,
 etc.
 Practically,
 this means that the contents of the function must be written in inline assembler.
 This is particularly useful for interrupt functions,
 which can have a large (and often unnecessary) prologue/epilogue.
 For example,
 compare the code generated by these two functions:
\end_layout

\begin_layout Verse

\family typewriter
volatile
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
volatile
\end_layout

\end_inset

 __data unsigned char counter;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void simpleInterrupt(void) __interrupt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

interrupt
\end_layout

\end_inset

 (1)
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

counter++;
\begin_inset Newline newline
\end_inset

}
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void nakedInterrupt(void) __interrupt (2) __naked
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__asm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

asm
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

_counter ;
 does not change flags,
 no need to save psw
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

reti
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 MUST explicitly include ret or reti in _naked function.
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__endasm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

endasm
\end_layout

\end_inset

;
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
For an 8051 target,
 the generated simpleInterrupt looks like:
\end_layout

\begin_layout Verse

\family typewriter
Note,
 this is an
\family default
 
\family typewriter
\emph on
outdated
\family default
\emph default
 
\family typewriter
example,
 recent versions of SDCC generate
\begin_inset Newline newline
\end_inset

the
\family default
 
\family typewriter
\emph on
same
\family default
\emph default
 
\family typewriter
code for simpleInterrupt() and nakedInterrupt()!
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

_simpleInterrupt:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

push
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

acc
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

push
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

b
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

push
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dpl
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

push
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dph
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

push
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

psw
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

psw,#0x00
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

_counter
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

pop
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

psw
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

pop
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dph
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

pop
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dpl
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

pop
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

b
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

pop
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

acc
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

reti
\end_layout

\begin_layout Standard
whereas nakedInterrupt looks like:
\end_layout

\begin_layout Verse

\family typewriter
_nakedInterrupt:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

_counter ;
 does not change flags,
 no need to save psw
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

reti
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 MUST explicitly include ret or reti in _naked function
\end_layout

\begin_layout Standard
The related directive #pragma exclude
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma exclude
\end_layout

\end_inset

 allows a more fine grained control over pushing & popping
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
push/pop
\end_layout

\end_inset

 the registers.
\end_layout

\begin_layout Standard
While there is nothing preventing you from writing C code inside a 
\family typewriter
_naked
\family default
 function,
 there are many ways to shoot yourself in the foot doing this,
 and it is recommended that you stick to inline assembler.
\end_layout

\begin_layout Subsection
Use of Labels within Inline Assembler
\end_layout

\begin_layout Standard
SDCC allows the use of in-line assembler with a few restrictions regarding labels.
 All labels defined within inline assembler code have to be of the form 
\emph on
nnnnn$
\emph default
 where nnnnn is a number less than 100 (which implies a limit of utmost 100 inline assembler labels 
\emph on
per function
\emph default
\noun on
)
\noun default
.
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
This is a slightly more stringent rule than absolutely necessary,
 but stays always on the safe side.
 Labels in the form of nnnnn$ are local labels in the assembler,
 locality of which is confined within two labels of the standard form.
 The compiler uses the same form for labels within a function (but starting from nnnnn=00100);
 and places always a standard label at the beginning of a function,
 thus limiting the locality of labels within the scope of the function.
 So,
 if the inline assembler part would be embedded into C-code,
 an improperly placed non-local label in the assembler would break up the reference space for labels created by the compiler for the C-code,
 leading to an assembling error.
\end_layout

\begin_layout Plain Layout
The numeric part of local labels does not need to have 5 digits (although this is the form of labels output by the compiler),
 any valid integer will do.
 Please refer to the assemblers documentation for further details.
\end_layout

\end_inset

 
\end_layout

\begin_layout Verse

\family typewriter
__asm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

asm
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

b,#10
\begin_inset Newline newline
\end_inset

00001$:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

djnz
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

b,00001$
\begin_inset Newline newline
\end_inset

__endasm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

endasm
\end_layout

\end_inset

 ;
\end_layout

\begin_layout Standard
Inline assembler code cannot reference any C-labels,
 however it can reference labels
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Labels
\end_layout

\end_inset

 defined by the inline assembler,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
foo() {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* some c code */
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__asm
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 some assembler code
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ljmp 0003$
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__endasm;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* some more c code */
\begin_inset Newline newline
\end_inset

clabel:
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* inline assembler cannot reference this label */ 
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
Here,
 the C-label 
\family typewriter
clabel
\family default
 is translated by the compiler into a local label,
 so the locality of labels within the function is not broken.
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__asm
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

0003$:
 ;label (can be referenced by inline assembler only)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__endasm
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

endasm
\end_layout

\end_inset

 ;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* some more c code */
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
In other words inline assembly code can access labels defined in inline assembly within the scope of the function.
 The same goes the other way,
 i.e.
 labels defines in inline assembly can not be accessed by C statements.
\end_layout

\begin_layout Section
Support routines for integer multiplicative operators
\end_layout

\begin_layout Standard
Depending on the target architecture,
 some integer multiplicative operators might be implemented by support routines.
 These support routines exist in portable C versions to facilitate porting to other MCUs,
 although depending on the target,
 assembler routines might be used instead.
 The following files contain some of the described routines,
 all of them can be found in <installdir>/share/sdcc/lib.
\begin_inset Newline newline
\end_inset


\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="11" columns="2">
<features tabularvalignment="middle">
<column alignment="left" valignment="top">
<column alignment="left" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
Function
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
Description
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
_mulint.c 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
16 bit multiplication
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
_divsint.c 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
 signed 16 bit division (calls _divuint)
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
_divuint.c 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
 unsigned 16 bit division
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
_modsint.c
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
signed 16 bit modulus (calls _moduint)
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
_moduint.c
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
unsigned 16 bit modulus
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
_mullong.c
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
32 bit multiplication
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
_divslong.c 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
 signed 32 division (calls _divulong)
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
_divulong.c 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
unsigned 32 division
\end_layout

\end_inset
</cell>
</row>
<row>
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\begin_inset Text

\begin_layout Plain Layout
_modslong.c
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
 signed 32 bit modulus (calls _modulong)
\end_layout

\end_inset
</cell>
</row>
<row>
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\begin_inset Text

\begin_layout Plain Layout
_modulong.c
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
unsigned 32 bit modulus
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
In the mcs51,
 ds390,
 hc08,
 s08,
 pdk13,
 pdk14,
 pdk15,
 pic14 and pic16 backends they are by default compiled as 
\emph on
non-reentrant
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
reentrant
\end_layout

\end_inset

;
 when targeting on of these architectures,
 interrupt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset

 service routines should not do any of the above operations.
 If this is unavoidable then the above routines will need to be compiled with the 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\end_layout

\end_inset


\emph default
 option,
 after which the source program will have to be compiled with 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-int-long-reent
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-int-long-reent
\end_layout

\end_inset


\emph default
 option.
 Notice that you don't have to call these routines directly.
 The compiler will use them automatically every time an integer operation is required.
\end_layout

\begin_layout Section
Floating Point Support
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Floating point support
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC supports (single precision 4 bytes) floating point numbers;
 the format is somewhat similar to IEEE,
 but it is not IEEE;
 in particular,
 denormalized floating -point numbers are not supported.
 The floating point support routines are derived from gcc's floatlib.c and consist of the following routines:
\begin_inset Newline newline
\end_inset


\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center

\size footnotesize
\begin_inset Tabular
<lyxtabular version="3" rows="19" columns="2">
<features tabularvalignment="middle">
<column alignment="left" valignment="top">
<column alignment="left" valignment="top">
<row>
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\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
Function 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Description
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
_fsadd.c
\end_layout

\end_inset
</cell>
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\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
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\emph off
\bar no
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\color none
add floating point numbers
\end_layout

\end_inset
</cell>
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<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
_fssub.c 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
subtract floating point numbers
\end_layout

\end_inset
</cell>
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<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
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\emph off
\bar no
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\color none
_fsdiv.c 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
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\color none
divide floating point numbers
\end_layout

\end_inset
</cell>
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<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

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\series medium
\shape up
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\emph off
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_fsmul.c 
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\end_inset
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\begin_inset Text

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\family roman
\series medium
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\emph off
\bar no
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multiply floating point numbers
\end_layout

\end_inset
</cell>
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<row>
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\begin_inset Text

\begin_layout Plain Layout

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\emph off
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_fs2uchar.c
\end_layout

\end_inset
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\begin_inset Text

\begin_layout Plain Layout

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\series medium
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\emph off
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convert floating point to unsigned char
\end_layout

\end_inset
</cell>
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<row>
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\begin_inset Text

\begin_layout Plain Layout

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_fs2schar.c
\end_layout

\end_inset
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convert floating point to signed char
\end_layout

\end_inset
</cell>
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<row>
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\begin_inset Text

\begin_layout Plain Layout

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_fs2uint.c
\end_layout

\end_inset
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\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
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\emph off
\bar no
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convert floating point to unsigned int
\end_layout

\end_inset
</cell>
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<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

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\series medium
\shape up
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\emph off
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_fs2sint.c
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\end_inset
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convert floating point to signed int
\end_layout

\end_inset
</cell>
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\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
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_fs2ulong.
\family default
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\end_layout

\end_inset
</cell>
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\begin_inset Text

\begin_layout Plain Layout

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convert floating point to unsigned long
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<row>
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\begin_inset Text

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\series medium
\shape up
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_fs2slong.c
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convert floating point to signed long
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_uchar2fs.c
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convert unsigned char to floating point
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\emph off
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_schar2fs.c
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_sint2fs.c
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_ulong2fs.c
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convert unsigned long long to floating point
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convert singed long long to floating point
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\begin_inset Newline newline
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\end_layout

\begin_layout Section
Library Routines
\begin_inset Index idx
range none
pageformat default
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\begin_layout Plain Layout
Libraries
\end_layout

\end_inset


\end_layout

\begin_layout Standard

\emph on
<pending:
 this is messy and incomplete - a little more information is at 
\emph default

\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/wiki/index.php/List_of_the_SDCC_library
\end_layout

\end_inset

>
\end_layout

\begin_layout Subsection
Compiler support routines (_gptrget,
 _mulint etc.)
\end_layout

\begin_layout Subsection
Stdclib functions (puts,
 printf,
 strcat etc.)
\end_layout

\begin_layout Subsubsection
<stdio.h>
\end_layout

\begin_layout Paragraph
getchar(),
 putchar()
\end_layout

\begin_layout Standard
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\begin_layout Plain Layout
<stdio.h>
\end_layout

\end_inset

As usual on embedded systems you have to provide your own 
\family typewriter
getchar()
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getchar()
\end_layout

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\family default
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putchar()
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putchar()
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printf()!putchar()
\end_layout

\end_inset


\family default
 routines.
 SDCC does not know whether the system connects to a serial line with or without handshake,
 LCD,
 keyboard or other device.
 And whether a 
\family typewriter
lf
\family default
 to 
\family typewriter
crlf
\family default
 conversion within 
\family typewriter
putchar()
\family default
 is intended.
 You'll find examples for serial routines f.e.
 in sdcc/device/lib.
 For the mcs51 this minimalistic polling 
\family typewriter
putchar()
\family default
 routine might be a start:
\end_layout

\begin_layout Verse

\family typewriter
int putchar (int c) {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

while (!TI)
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
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 /* assumes UART is initialized */
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;
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\begin_inset space ~
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TI = 0;
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\begin_inset space ~
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\begin_inset space ~
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SBUF = c;
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\begin_layout Verse

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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
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\begin_inset space ~
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return c;
\end_layout

\begin_layout Verse

\family typewriter
}
\end_layout

\begin_layout Paragraph
printf()
\end_layout

\begin_layout Standard
The default 
\family typewriter
printf()
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printf()
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\family default
 implementation in 
\family typewriter
printf_large.c
\family default
 does not support float
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\begin_layout Plain Layout
Floating point support
\end_layout

\end_inset

 (except on ds390),
 only <NO FLOAT>
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<NO FLOAT>
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\begin_layout Plain Layout
printf()!floating point support
\end_layout

\end_inset

 will be printed instead of the value.
 To enable floating point output,
 recompile it with the option 
\emph on
-
\begin_inset ERT
status collapsed

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\backslash
/
\end_layout

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DUSE_FLOATS=1
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USE
\begin_inset ERT
status collapsed

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\backslash
_
\end_layout

\end_inset

FLOATS
\end_layout

\end_inset


\emph default
 on the command line.
 Use 
\emph on
-
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\backslash
/
\end_layout

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-model-large
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\backslash
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\end_layout

\end_inset

-model-large
\end_layout

\end_inset


\emph default
 for the mcs51 port,
 since this uses a lot of memory.
 To enable float support for the pic16 targets,
 see 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:pic16Libraries"
nolink "false"

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.
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 '!',
 '
\backslash
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 standard 8051 @ 22.1184 MHz,
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\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.40 / 0.40 ms
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
-
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
float speed
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
Execution time of printf("%.3f",
 -12345.678);
 standard 8051 @ 22.1184 MHz,
 empty putchar()
\end_layout

\end_inset

,
\end_layout

\begin_layout Plain Layout
small / large
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
-
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
7.49 / 22.47 ms
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
-
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
-
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1.04 / 1.04 ms
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
-
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Subsubsection
<malloc.h>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
malloc.h
\end_layout

\end_inset


\end_layout

\begin_layout Standard
As of SDCC 2.6.2 you no longer need to call an initialization routine before using dynamic memory allocation
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
dynamic memory allocation (malloc)
\end_layout

\end_inset

 and a default heap
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
heap (malloc)
\end_layout

\end_inset

 space of 1024 bytes is provided for malloc to allocate memory from.
 If you need a different heap size you need to recompile _heap.c with the required size defined in HEAP_SIZE.
 It is recommended to make a copy of this file into your project directory and compile it there with:
\end_layout

\begin_layout Verse

\family typewriter
sdcc -c _heap.c -D HEAP_SIZE=2048
\end_layout

\begin_layout Standard
And then link it with:
\end_layout

\begin_layout Verse

\family typewriter
sdcc main.rel _heap.rel
\end_layout

\begin_layout Subsection
Math functions (sinf,
 powf,
 sqrtf etc.)
\end_layout

\begin_layout Subsubsection
<math.h>
\end_layout

\begin_layout Standard
See definitions in file <math.h>.
\end_layout

\begin_layout Subsection
Other libraries
\end_layout

\begin_layout Standard
Libraries
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Libraries
\end_layout

\end_inset

 included in SDCC should have a license at least as liberal as the GPLv2+LE
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
GPLv2+LE
\end_layout

\end_inset

.
 Exception are pic device libraries and header files which are derived from Microchip header (.inc) and linker script (.lkr) files.
 Microchip requires that "The header files should state that they are only to be used with authentic Microchip devices" which makes them incompatible with GPL.
\end_layout

\begin_layout Standard
If you have ported some library or want to share experience about some code which f.e.
 falls into any of these categories Busses (I
\begin_inset Formula $^{\textrm{2}}$
\end_inset

C,
 CAN,
 Ethernet,
 Profibus,
 Modbus,
 USB,
 SPI,
 JTAG ...),
 Media (IDE,
 Memory cards,
 eeprom,
 flash...),
 En-/Decryption,
 Remote debugging,
 Realtime kernel,
 Keyboard,
 LCD,
 RTC,
 FPGA,
 PID then the sdcc-user mailing list 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/p/sdcc/mailman/sdcc-user/
\end_layout

\end_inset

 would certainly like to hear about it.
\end_layout

\begin_layout Standard
Programmers coding for embedded systems are not especially famous for being enthusiastic,
 so don't expect a big hurray but as the mailing list is searchable these references are very valuable.
 Let's help to create a climate where information is shared.
\end_layout

\begin_layout Section
Memory Models
\end_layout

\begin_layout Subsection
MCS51 Memory Models
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Memory model
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
MCS51 memory model
\end_layout

\end_inset


\end_layout

\begin_layout Subsubsection
Small,
 Medium,
 Large and Huge
\end_layout

\begin_layout Standard
SDCC allows four memory models for MCS51 code,
 
\shape slanted
small,
 medium,
 large
\shape default
 and 
\shape slanted
huge
\shape default
.
 Modules compiled with different memory models should 
\emph on
never
\emph default
 be combined together or the results would be unpredictable.
 The library routines supplied with the compiler are compiled for all models (however,
 the libraries for –stack-auto are compiled for the small and large models only).
 The compiled library modules are contained in separate directories as small,
 medium,
 large and huge so that you can link to the appropriate set.
\end_layout

\begin_layout Standard
When the medium,
 large or huge model is used all variables declared without specifying an intrinsic named address space will be allocated into the external ram,
 this includes all parameters and local variables (for non-reentrant
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
reentrant
\end_layout

\end_inset

 functions).
 Medium model uses pdata and large and huge models use xdata.
 When the small model is used variables without an explicitly specified intrinsic named address space are allocated in the internal ram.
\end_layout

\begin_layout Standard
The huge model compiles all functions as 
\emph on
banked
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Bankswitching"
nolink "false"

\end_inset


\emph default
 and is otherwise equal to large for now.
 All other models compile the functions without bankswitching by default.
\end_layout

\begin_layout Standard
Judicious usage of the processor specific intrinsic named address spaces
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
intrinsic named address space
\end_layout

\end_inset

 and the 'reentrant' function type will yield much more efficient code,
 than using the large model.
 Several optimizations are disabled when the program is compiled using the large model,
 it is therefore recommended that the small model be used unless absolutely required.
\end_layout

\begin_layout Subsubsection
External Stack
\begin_inset CommandInset label
LatexCommand label
name "subsec:External-Stack"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
External stack (mcs51)
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The external stack (-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack option
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack
\end_layout

\end_inset

) is located in pdata
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

pdata (mcs51,
 ds390 named address space)
\end_layout

\end_inset

 memory (usually at the start of the external ram segment) and uses all unused space in pdata (max.
 256 bytes).
 When -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-xstack option is used to compile the program,
 the parameters and local variables
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
local variables
\end_layout

\end_inset

 of all reentrant functions are allocated in this area.
 This option is provided for programs with large stack space requirements.
 When used with the -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\end_layout

\end_inset

 option,
 all parameters and local variables are allocated on the external stack (note:
 support libraries will need to be recompiled with the same options.
 There is a predefined target in the library makefile).
\end_layout

\begin_layout Standard
The compiler outputs the higher order address byte of the external ram segment into port P2
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
P2 (mcs51 sfr)
\end_layout

\end_inset

 (see also section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:MCS51-variants"
nolink "false"

\end_inset

),
 therefore when using the External Stack option,
 this port 
\emph on
may not
\emph default
 be used by the application program.
\end_layout

\begin_layout Subsection
DS390 Memory Model
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Memory model
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS390 memory model
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The only model supported is Flat 24
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Flat 24 (DS390 memory model)
\end_layout

\end_inset

.
 This generates code for the 24 bit contiguous addressing mode of the Dallas DS80C390 part.
 In this mode,
 up to four meg of external RAM or code space can be directly addressed.
 See the data sheets at www.dalsemi.com for further information on this part.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Note that the compiler does not generate any code to place the processor into 24 bit mode (although 
\emph on
tinibios
\emph default
 in the ds390 libraries will do that for you).
 If you don't use 
\emph on
tinibios
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Tinibios (DS390)
\end_layout

\end_inset

,
 the boot loader or similar code must ensure that the processor is in 24 bit contiguous addressing mode before calling the SDCC startup code.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Like the 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-model-large
\emph default
 option,
 variables will by default be placed into the XDATA segment.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Segments may be placed anywhere in the 4 meg address space using the usual -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-*-loc options.
 Note that if any segments are located above 64K,
 the -r flag must be passed to the linker to generate the proper segment relocations,
 and the Intel HEX output format must be used.
 The -r flag can be passed to the linker by using the option 
\emph on
-Wl-r
\emph default
 on the SDCC command line.
 However,
 currently the linker can not handle code segments > 64k.
\end_layout

\begin_layout Subsection
STM8 Memory Models
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Memory model
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
STM8 memory models
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC implements two memory models for the STM8:
 
\emph on
medium
\emph default
 (default) and 
\emph on
large
\emph default
.
 Modules compiled with different memory models should 
\emph on
never
\emph default
 be combined together.
 The library routines supplied with the compiler are compiled for all models.
\end_layout

\begin_layout Standard
In the medium model the address space is 16 bits for both objects and functions,
 allowing for a memory space of 64 KB.
 Since the STM8 typically has Flash starting at 0x8000,
 this means that only up to 32 KB of Flash can be used (most STM8 devices don't have more than 32 KB of Flash).
\end_layout

\begin_layout Standard
In the large memory model,
 the address space is 16 bits for objects and 24 bits for functions.
 Since the STM8 typically has flash starting at 0x8000,
 this means that up to 32 KB of flash can be used for constant data,
 while the whole Flash can be used for functions.
 Code generated for the large model is slightly bigger and slower and needs slightly more stack space than code generated for the medium model.
\end_layout

\begin_layout Subsection
MOS6502 Memory Models
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Memory model
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
MOS6502 memory models
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC implements two memory models for the MOS6502:
 
\emph on
small
\emph default
 and 
\emph on
large
\emph default
 (default).
 Modules compiled with different memory models should 
\emph on
never
\emph default
 be combined together.
 The library routines supplied with the compiler are compiled for all models.
\end_layout

\begin_layout Standard
In the small model all data objects are placed by default in Page Zero.
 This is normally only useful in embedded systems.
\end_layout

\begin_layout Standard
In the large memory model,
 data is placed by default in 16-bit addressable memory.
 Critical data can still be placed in Page Zero using the __ZP or __near storage modifier.
 Code generated for the large model is slightly bigger and slower than code generated for the small model.
\end_layout

\begin_layout Section
Pragmas
\begin_inset CommandInset label
LatexCommand label
name "sec:Pragmas"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Pragmas
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Pragmas are used to turn on and/or off certain compiler options.
 Some of them are closely related to corresponding command-line options (see section 
\begin_inset CommandInset ref
LatexCommand vref
reference "sec:Command-Line-Options"
nolink "false"

\end_inset

).
\begin_inset Newline newline
\end_inset

Pragmas should be placed before and/or after a function,
 placing pragmas inside a function body could have unpredictable results.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

SDCC supports the following #pragma directives:
\end_layout

\begin_layout Itemize

\series bold
save
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma save
\end_layout

\end_inset

 - this will save most current options to the save/restore stack.
 See #pragma
\begin_inset space ~
\end_inset

restore.
\end_layout

\begin_layout Itemize

\series bold
restore
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma restore
\end_layout

\end_inset

 - will restore saved options from the last save.
 saves & restores can be nested.
 SDCC uses a save/restore stack:
 save pushes current options to the stack,
 restore pulls current options from the stack.
 See #pragma
\begin_inset space ~
\end_inset

save.
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Itemize

\series bold
callee_saves
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma callee
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

saves
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
function prologue
\end_layout

\end_inset

 function1[,function2[,function3...]] 
\begin_inset CommandInset label
LatexCommand label
name "ite:callee_saves-function1[,function2[,function3...]]--"

\end_inset

- The compiler by default uses a caller saves convention for register saving across function calls,
 however this can cause unnecessary register pushing and popping
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
push/pop
\end_layout

\end_inset

 when calling small functions from larger functions.
 This option can be used to switch off the register saving convention for the function names specified.
 The compiler will not save registers when calling these functions,
 extra code need to be manually inserted at the entry and exit for these functions to save and restore the registers used by these functions,
 this can SUBSTANTIALLY reduce code and improve run time performance of the generated code.
 In the future the compiler (with inter procedural analysis) may be able to determine the appropriate scheme to use for each function call.
 If -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-callee-saves command line option is used (see page 
\begin_inset CommandInset ref
LatexCommand vpageref
reference "lyx:--callee-saves-function1[,function2][,function3]..."
nolink "false"

\end_inset

),
 the function names specified in #pragma
\begin_inset space ~
\end_inset

callee_saves
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma callee
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

saves
\end_layout

\end_inset

 is appended to the list of functions specified in the command line.
\end_layout

\begin_layout Itemize

\series bold
exclude
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma exclude
\end_layout

\end_inset

 none | {acc[,b[,dpl[,dph[,bits]]]]} - The exclude pragma disables the generation of pairs of push/pop
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
push/pop
\end_layout

\end_inset

 instructions in 
\emph on
I
\emph default
nterrupt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset

 
\emph on
S
\emph default
ervice 
\emph on
R
\emph default
outines.
 The directive should be placed immediately before the ISR function definition and it affects ALL ISR functions following it.
 To enable the normal register saving for ISR functions use #pragma
\begin_inset space ~
\end_inset

exclude
\begin_inset space ~
\end_inset

none
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma exclude
\end_layout

\end_inset

.
 See also the related keyword 
\emph on
__naked
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

naked
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

naked
\end_layout

\end_inset

.
\end_layout

\begin_layout Itemize

\series bold
less_pedantic
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
pedantic
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma less
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

pedantic
\end_layout

\end_inset


\begin_inset CommandInset label
LatexCommand label
name "ite:less_pedantic"

\end_inset

 - the compiler will not warn you anymore for obvious mistakes,
 you're on your own now ;-(.
 See also the command line option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-less-pedantic 
\begin_inset CommandInset ref
LatexCommand vpageref
reference "lyx:--less-pedantic"
nolink "false"

\end_inset

.
 
\begin_inset Newline newline
\end_inset

More specifically,
 the following warnings will be disabled:
 
\shape italic
comparison is always [true/false] due to limited range of data type
\shape default
 (94);
 
\shape italic
overflow in implicit constant conversion
\shape default
 (158);
 [the (in)famous] 
\shape italic
conditional flow changed by optimizer:
 so said EVELYN the modified DOG
\shape default
 (110);
 
\shape italic
function '[function name]' must return value
\shape default
 (59).
 
\begin_inset Newline newline
\end_inset

Furthermore,
 warnings of less importance (of PEDANTIC and INFO warning level) are disabled,
 too,
 namely:
 
\shape italic
constant value '[
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
dunno what comes here - this warning appears to be unused altogether
\end_layout

\end_inset

]',
 out of range
\shape default
 (81);
 
\shape italic
[left/right] shifting more than size of object changed to zero
\shape default
 (116);
 
\shape italic
unreachable code
\shape default
 (126);
 
\shape italic
integer overflow in expression
\shape default
 (165);
 
\shape italic
unmatched #pragma save and #pragma restore
\shape default
 (170);
 
\shape italic
comparison of 'signed char' with 'unsigned char' requires promotion to int
\shape default
 (185);
 
\shape italic
ISO C90 does not support flexible array members
\shape default
 (187);
 
\shape italic
extended stack by [number] bytes for compiler temp(s) :in function '[function
\begin_inset space ~
\end_inset

name]':
\begin_inset space ~
\end_inset

[
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
appears to be always blank - what was supposed to be here?
\end_layout

\end_inset

]
\shape default
 (114);
 
\shape italic
function '[function name]',
 # edges [number] ,
 # nodes [number] ,
 cyclomatic complexity [number]
\shape default
 (121).
\end_layout

\begin_layout Itemize

\series bold
disable_warning
\series default
 <nnnn>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma disable
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

warning
\end_layout

\end_inset

 - the compiler will not warn you anymore about warning number <nnnn>.
\end_layout

\begin_layout Itemize

\series bold
nogcse
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma nogcse
\end_layout

\end_inset

 - will stop global common subexpression elimination.
\end_layout

\begin_layout Itemize

\series bold
noinduction
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma noinduction
\end_layout

\end_inset

 - will stop loop induction optimizations.
\end_layout

\begin_layout Itemize

\series bold
noinvariant
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma noinvariant
\end_layout

\end_inset

 - will not do loop invariant optimizations.
 For more details see Loop Invariants in section
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Loop-Optimizations"
nolink "false"

\end_inset

.
\end_layout

\begin_layout Itemize

\series bold
noiv
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma noiv
\end_layout

\end_inset

 - Do not generate interrupt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt
\end_layout

\end_inset

 vector table
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
interrupt vector table
\end_layout

\end_inset

 entries for all ISR functions defined after the pragma.
 This is useful in cases where the interrupt vector table must be defined manually,
 or when there is a secondary,
 manually defined interrupt vector table (e.g.
 for the autovector feature of the Cypress EZ-USB FX2).
 More elegantly this can be achieved by omitting the optional interrupt number after the 
\emph on
__interrupt
\emph default
 keyword,
 see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Interrupt-Service-Routines"
nolink "false"

\end_inset


\begin_inset space ~
\end_inset

about interrupts.
\end_layout

\begin_layout Itemize

\series bold
noloopreverse
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma noloopreverse
\end_layout

\end_inset

 - Will not do loop reversal optimization
\end_layout

\begin_layout Itemize

\series bold
nooverlay
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma nooverlay
\end_layout

\end_inset

 - the compiler will not overlay the parameters and local variables of a function.
\end_layout

\begin_layout Itemize

\series bold
stackauto
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma stackauto
\end_layout

\end_inset

- See option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto
\end_layout

\end_inset

 and section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Parameters-and-Local-Variables"
nolink "false"

\end_inset

 Parameters and Local Variables.
\end_layout

\begin_layout Itemize

\series bold
opt_code_speed
\series default
 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma opt
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

code
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

speed
\end_layout

\end_inset

- The compiler will optimize code generation towards fast code,
 possibly at the expense of code size.
\end_layout

\begin_layout Itemize

\series bold
opt_code_size
\series default
 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma opt
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

code
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

size
\end_layout

\end_inset

- The compiler will optimize code generation towards compact code,
 possibly at the expense of code speed.
 
\end_layout

\begin_layout Itemize

\series bold
opt_code_balanced
\series default
 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma opt
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

code
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

balanced
\end_layout

\end_inset

- The compiler will attempt to generate code that is both compact and fast,
 as long as meeting one goal is not a detriment to the other (this is the default).
 
\end_layout

\begin_layout Itemize

\series bold
std_sdcc89
\series default
 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma std
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sdcc89
\end_layout

\end_inset

- Generally follow the C89 standard,
 but allow SDCC features that conflict with the standard.
\end_layout

\begin_layout Itemize

\series bold
std_c89
\series default
 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma std
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

c89
\end_layout

\end_inset

- Follow the C89 standard and disable SDCC features that conflict with the standard.
\end_layout

\begin_layout Itemize

\series bold
std_sdcc99
\series default
 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma std
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sdcc99
\end_layout

\end_inset

- Generally follow the C99 standard,
 but allow SDCC features that conflict with the standard.
\end_layout

\begin_layout Itemize

\series bold
std_c99
\series default
 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma std
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

c99
\end_layout

\end_inset

- Follow the C99 standard and disable SDCC features that conflict with the standard.
\end_layout

\begin_layout Itemize

\series bold
std_c11
\series default
 
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma std
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

c11
\end_layout

\end_inset

- Follow the C11 standard and disable SDCC features that conflict with the standard.
\end_layout

\begin_layout Itemize

\series bold
std_sdcc11
\series default
 
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma std
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sdcc11
\end_layout

\end_inset

- Generally follow the C11 standard,
 but allow SDCC features that conflict with the standard.
\end_layout

\begin_layout Itemize

\series bold
std_c23
\series default

\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma std
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

c23
\end_layout

\end_inset

- Follow the C23 standard and disable SDCC features that conflict with the standard (for backwards compatibility,
 
\series bold
std_c2x
\series default
 still exists as an alias).
\end_layout

\begin_layout Itemize

\series bold
std_sdcc23
\series default
 
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma std
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sdcc23
\end_layout

\end_inset

- Generally follow the C23 standard,
 but allow SDCC features that conflict with the standard.
\end_layout

\begin_layout Itemize

\series bold
std_c2
\series default
y
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma std
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

c2y
\end_layout

\end_inset

- Follow the C2y standard and disable SDCC features that conflict with the standard.
\end_layout

\begin_layout Itemize

\series bold
std_sdcc2y
\series default
 
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma std
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

sdcc2y
\end_layout

\end_inset

- Generally follow the C2y standard,
 but allow SDCC features that conflict with the standard.
\end_layout

\begin_layout Itemize

\series bold
codeseg
\series default
 <name>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma codeseg
\end_layout

\end_inset

- Use this name (max.
 8 characters) for the code segment.
 See option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-codeseg.
\end_layout

\begin_layout Itemize

\series bold
constseg
\series default
 <name>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma constseg
\end_layout

\end_inset

- Use this name (max.
 8 characters) for the const segment.
 See option -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-constseg.
\end_layout

\begin_layout Standard
The preprocessor
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Preprocessor
\end_layout

\end_inset

 SDCPP
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sdcpp (preprocessor)
\end_layout

\end_inset

 supports the following #pragma directives:
\end_layout

\begin_layout Itemize

\series bold
preproc_asm
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma preproc
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

asm
\end_layout

\end_inset

 (+ | -) - switch the __asm __endasm block preprocessing on / off.
 Default is on.
 Below is an example on how to use this pragma.
\end_layout

\begin_layout Verse

\family typewriter
#pragma preproc_asm -
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma preproc
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

asm
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset

/* this is a c code nop */
\begin_inset Newline newline
\end_inset

#define NOP ;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void foo (void)
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

while (--i)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

NOP
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__asm
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 this is an assembler nop instruction
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 it is not preprocessed to ';' since the asm preprocessing is disabled
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

NOP
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

__endasm;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset

}
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Verse
The pragma preproc_asm should not be used to define multilines of assembly code (even if it supports it),
 since this behavior is only a side effect of sdcpp __asm __endasm implementation in combination with pragma preproc_asm and is not in conformance with the C standard.
 This behavior might be changed in the future sdcpp versions.
 To define multilines of assembly code you have to include each assembly line into it's own __asm __endasm block.
 Below is an example for multiline assembly defines.
\end_layout

\begin_layout Verse

\family typewriter
#define Nop __asm 
\backslash

\begin_inset Newline newline
\end_inset

nop 
\backslash

\begin_inset Newline newline
\end_inset

__endasm
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

#define ThreeNops Nop;
 
\backslash

\begin_inset Newline newline
\end_inset

Nop;
 
\backslash

\begin_inset Newline newline
\end_inset

Nop
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void foo (void)
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ThreeNops;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset

}
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Itemize

\series bold
sdcc_hash
\series default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma sdcc
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

hash
\end_layout

\end_inset

 (+ | -) - 
\begin_inset Flex Emph
status open

\begin_layout Plain Layout
Until SDCC 4.2.8:
\end_layout

\end_inset

 Allow "naked" hash in macro definition,
 for example:
\begin_inset Newline newline
\end_inset


\family typewriter
#define DIR_LO(x) #(x & 0xff)
\family default

\begin_inset Newline newline
\end_inset

Default is off.
 Below is an example on how to use this pragma.
\end_layout

\begin_layout Verse

\family typewriter
#pragma preproc_asm +
\begin_inset Newline newline
\end_inset

#pragma sdcc_hash +
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma sdcc
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

hash
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

#define ROMCALL(x) 
\backslash

\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov R6_B3,
 #(x & 0xff) 
\backslash

\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov R7_B3,
 #((x >> 8) & 0xff) 
\backslash

\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

lcall __romcall
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

...
\begin_inset Newline newline
\end_inset

__asm
\begin_inset Newline newline
\end_inset

ROMCALL(72)
\begin_inset Newline newline
\end_inset

__endasm;
\begin_inset Newline newline
\end_inset

...
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
Some of the pragmas are intended to be used to turn-on or off certain optimizations which might cause the compiler to generate extra stack and/or data space to store compiler generated temporary variables.
 This usually happens in large functions.
 Pragma directives should be used as shown in the following example,
 they are used to control options and optimizations for a given function.
 
\end_layout

\begin_layout Verse

\family typewriter
#pragma save
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma save
\end_layout

\end_inset

 
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* save the current settings */
\begin_inset Newline newline
\end_inset

#pragma nogcse
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma nogcse
\end_layout

\end_inset

 
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* turnoff global subexpression elimination */
\begin_inset Newline newline
\end_inset

#pragma noinduction
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma noinduction
\end_layout

\end_inset

 /* turn off induction optimizations */
\begin_inset Newline newline
\end_inset

int foo ()
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 /* large code */
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 ...
\begin_inset Newline newline
\end_inset

}
\begin_inset Newline newline
\end_inset

#pragma restore
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma restore
\end_layout

\end_inset

 /* turn the optimizations back on */
\end_layout

\begin_layout Standard
The compiler will generate a warning message when extra space is allocated.
 It is strongly recommended that the save and restore pragmas be used when changing options for a function.
\end_layout

\begin_layout Section
Defines Created by the Compiler
\end_layout

\begin_layout Standard
Besides defines from the C standards,
 the compiler creates the following #defines
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

defines
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Defines created by the compiler
\end_layout

\end_inset

:
\begin_inset Newline newline
\end_inset


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OBSOLETE.
 WILL BE REMOVED IN THE FUTURE.
 CURRENTLY Only defined for the mcs51 backend (and only if –std-cXX is not used).
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 256).
 PLEASE USE OTHER VERSION MACROS INSTEAD!
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z80
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SDCC!Defines!SDCC
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XSTACK
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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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when 
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-
\begin_inset ERT
status collapsed

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\emph default
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<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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\begin_layout Plain Layout
SDCC!Defines!SDCC
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


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_
\end_layout

\end_inset

STACK
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

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TENBIT (ds390)
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
when 
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-mds390
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MODEL
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FLAT24 (ds390)
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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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\emph default
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__SDCC_VERSION_MAJOR
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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Always defined.
 SDCC major version number.
 E.g.
 3 for SDCC 3.5.0
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__SDCC_VERSION_MINOR
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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

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Always defined.
 SDCC minor version number.
 E.g.
 5 for SDCC 3.5.0
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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

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Always defined.
 SDCC patchlevel version number.
 E.g.
 0 for SDCC 3.5.0
\end_layout

\end_inset
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<row>
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SDCC!Defines!SDCC
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\end_inset

REVISION (svn revision number)
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</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Always defined.
 SDCC svn revision number.
 Older versions of sdcc used SDCC_REVISION instead.
\end_layout

\end_inset
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<row>
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pageformat default
status collapsed

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SDCC!Defines!SDCC
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PARMS
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IN
\begin_inset ERT
status collapsed

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\backslash
_
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\end_inset

BANK1
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\end_layout

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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
when 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-parms-in-bank1
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<row>
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_
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ALL
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CALLEE
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SAVES
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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

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\emph on
-
\begin_inset ERT
status collapsed

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\end_inset

-all-callee-saves
\emph default
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FLOAT
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REENT
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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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when 
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-
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status collapsed

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\backslash
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\end_layout

\end_inset

-float-reent
\emph default
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INT
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LONG
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REENT
\end_layout

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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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\begin_inset ERT
status collapsed

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-int-long-reent
\emph default
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OPTIMIZE
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SPEED
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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
when 
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-
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status collapsed

\begin_layout Plain Layout


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-opt-code-speed
\emph default
 is used
\end_layout

\end_inset
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<row>
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\begin_inset Index idx
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status collapsed

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SDCC!Defines!SDCC
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

OPTIMIZE
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

SIZE
\end_layout

\end_inset


\end_layout

\end_inset
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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
when 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
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\end_layout

\end_inset

-opt-code-size
\emph default
 is used
\end_layout

\end_inset
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<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
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__SDCCCALL
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Defines!SDCCCALL
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Default ABI version for calling convention
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Chapter
Notes on supported Processors
\end_layout

\begin_layout Section
MCS51 variants
\begin_inset CommandInset label
LatexCommand label
name "subsec:MCS51-variants"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
MCS51 variants
\end_layout

\end_inset


\end_layout

\begin_layout Standard
MCS51 processors are available from many vendors and come in many different flavours.
 While they might differ considerably in respect to Special Function Registers the core MCS51 is usually not modified or is kept compatible.
 
\end_layout

\begin_layout Subsection
pdata access by SFR
\end_layout

\begin_layout Standard
With the upcome of devices with internal xdata and flash memory devices using port P2
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
P2 (mcs51 sfr)
\end_layout

\end_inset

 as dedicated I/O port is becoming more popular.
 Switching the high byte for __pdata
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range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
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\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

pdata (mcs51,
 ds390 named address space)
\end_layout

\end_inset

 access which was formerly done by port P2 is then achieved by a Special Function Register
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
sfr
\end_layout

\end_inset

.
 In well-established MCS51 tradition the address of this 
\emph on
sfr
\emph default
 is where the chip designers decided to put it.
 Needless to say that they didn't agree on a common name either.
 So that the startup code can correctly initialize xdata variables,
 you should define an sfr with the name _XPAGE
\family typewriter

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range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

XPAGE (mcs51)
\end_layout

\end_inset


\family default
 at the appropriate location if the default,
 port P2,
 is not used for this.
 Some examples are:
\end_layout

\begin_layout Verse

\family typewriter
__sfr __at (0x85) _XPAGE;
 /* Ramtron VRS51 family a.k.a.
 MPAGE */
\end_layout

\begin_layout Verse

\family typewriter
__sfr __at (0x92) _XPAGE;
 /* Cypress EZ-USB family,
 Texas Instruments (Chipcon) a.k.a.
 MPAGE */
\end_layout

\begin_layout Verse

\family typewriter
__sfr __at (0x91) _XPAGE;
 /* Infineon (Siemens) C500 family a.k.a.
 XPAGE */
\end_layout

\begin_layout Verse

\family typewriter
__sfr __at (0xaf) _XPAGE;
 /* some Silicon Labs (Cygnal) chips a.k.a.
 EMI0CN */
\end_layout

\begin_layout Verse

\family typewriter
__sfr __at (0xaa) _XPAGE;
 /* some Silicon Labs (Cygnal) chips a.k.a.
 EMI0CN */
\end_layout

\begin_layout Standard
There are also devices without anything resembling _XPAGE,
 but luckily they usually have dual data-pointers.
 For these devices a different method can be used to correctly initialize xdata variables.
 A default implementation is already in crtxinit.asm but it needs to be assembled manually with DUAL_DPTR set to 1.
\end_layout

\begin_layout Standard
For more exotic implementations further customizations may be needed.
 See section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:MCS51-Startup-Code"
nolink "false"

\end_inset

 for other possibilities.
\end_layout

\begin_layout Subsection
Other Features available by SFR
\end_layout

\begin_layout Standard
Some MCS51 variants offer features like Dual DPTR
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DPTR
\end_layout

\end_inset

,
 multiple DPTR,
 decrementing DPTR,
 16x16 Multiply.
 These are currently not used for the MCS51 port.
 If you absolutely need them you can fall back to inline assembly or submit a patch to SDCC.
\end_layout

\begin_layout Subsection
Bankswitching
\begin_inset CommandInset label
LatexCommand label
name "subsec:Bankswitching"

\end_inset


\end_layout

\begin_layout Standard
Bankswitching
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Bankswitching
\end_layout

\end_inset

 (a.k.a.
 code banking
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
code banking
\end_layout

\end_inset

) is a technique to increase the code space above the 64k limit of the 8051.
\end_layout

\begin_layout Subsubsection
Hardware
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="4">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell multicolumn="1" alignment="center" valignment="top" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
8000-FFFF
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
bank1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
bank2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
bank3
\end_layout

\end_inset
</cell>
</row>
<row>
<cell multicolumn="1" alignment="center" valignment="top" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0000-7FFF
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
common
\end_layout

\end_inset
</cell>
<cell multicolumn="1" alignment="center" valignment="top" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell multicolumn="2" alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
</row>
<row>
<cell multicolumn="1" alignment="center" valignment="top" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SiLabs C8051F120 example
\end_layout

\end_inset
</cell>
<cell multicolumn="2" alignment="center" valignment="top" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell multicolumn="2" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell multicolumn="2" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Usually the hardware uses some sfr (an output port or an internal sfr) to select a bank and put it in the banked area of the memory map.
 The selected bank usually becomes active immediately upon assignment to this sfr and when running inside a bank it will switch out this code it is currently running.
 Therefor you cannot jump or call directly from one bank to another and need to use a so-called trampoline in the common area.
 For SDCC an example trampoline is in crtbank.asm and you may need to change it to your 8051 derivative or schematic.
 The presented code is written for the C8051F120.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

When calling a banked function SDCC will put the LSB of the functions address in register R0,
 the MSB in R1 and the bank in R2 and then call this trampoline 
\emph on
__sdcc_banked_call
\emph default
.
 The current selected bank is saved on the stack,
 the new bank is selected and an indirect jump is made.
 When the banked function returns it jumps to 
\emph on
__sdcc_banked_ret
\emph default
 which restores the previous bank and returns to the caller.
\end_layout

\begin_layout Subsubsection
Software
\end_layout

\begin_layout Standard
When writing banked software using SDCC you need to use some special keywords and options.
 You also need to take over a bit of work from the linker.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

To create a function that can be called from another bank it requires the keyword 
\emph on
__banked
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
banked
\end_layout

\end_inset

.
 The caller must see this in the prototype of the callee and the callee needs it for a proper return.
 Called functions within the same bank as the caller do not need the 
\emph on
__banked
\emph default
 keyword nor do functions in the common area.
 Beware:
 SDCC does not know or check if functions are in the same bank.
 This is your responsibility!
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Normally all functions you write end up in the segment CSEG.
 If you want a function explicitly to reside in the common area put it in segment HOME.
 This applies for instance to interrupt service routines as they should not be banked.
\end_layout

\begin_layout Standard
Functions that need to be in a switched bank must be put in a named segment.
 The name can be mostly anything up to eight characters (e.g.
 BANK1).
 To do this you either use -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-codeseg BANK1 (See 
\begin_inset CommandInset ref
LatexCommand ref
reference "lyx:-codeseg"
nolink "false"

\end_inset

) on the command line when compiling or #pragma codeseg BANK1 (See 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Pragmas"
nolink "false"

\end_inset

) at the top of the C source file.
 The segment name always applies to the whole source file and generated object so functions for different banks need to be defined in different source files.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

When linking your objects you need to tell the linker where to put your segments.
 To do this you use the following command line option to SDCC:
 -Wl-b BANK1=0x18000 (See 
\begin_inset CommandInset ref
LatexCommand ref
reference "lyx:-Wl option"
nolink "false"

\end_inset

).
 This sets the virtual start address of this segment.
 It sets the banknumber to 0x01 and maps the bank to 0x8000 and up.
 The linker will not check for overflows,
 again this is your responsibility.
\end_layout

\begin_layout Subsection
MCS51/DS390 Startup Code
\begin_inset CommandInset label
LatexCommand label
name "subsec:MCS51-Startup-Code"

\end_inset


\end_layout

\begin_layout Standard
The compiler triggers the linker to link certain initialization modules from the runtime library
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Runtime library
\end_layout

\end_inset

 called crt<something>.
 Only the necessary ones are linked,
 for instance crtxstack.asm (GSINIT1,
 GSINIT5) is not linked unless the -
\series bold

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series default
-xstack option is used.
 These modules are highly entangled by the use of special segments/areas,
 but a common layout is shown below:
\end_layout

\begin_layout Verse

\family typewriter
\series bold
\size footnotesize
(main.asm)
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area HOME (CODE)
\begin_inset Newline newline
\end_inset

__interrupt_vect:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ljmp __sdcc_gsinit_startup
\end_layout

\begin_layout Verse

\family typewriter
\series bold
\size footnotesize
(crtstart.asm)
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area GSINIT0 (CODE)
\begin_inset Newline newline
\end_inset

__sdcc_gsinit_startup::
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov sp,#__start__stack - 1
\end_layout

\begin_layout Verse

\family typewriter
\series bold
\size footnotesize
(crtxstack.asm)
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area GSINIT1 (CODE)
\begin_inset Newline newline
\end_inset

__sdcc_init_xstack::
\begin_inset Newline newline
\end_inset

;
 Need to initialize in GSINIT1 in case the user's __sdcc_external_startup uses the xstack.
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov __XPAGE,#(__start__xstack >> 8)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov _spx,#__start__xstack
\end_layout

\begin_layout Verse

\family typewriter
\series bold
\size footnotesize
(crtstart.asm)
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area GSINIT2 (CODE)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

lcall ___sdcc_external_startup
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,dpl
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

jz __sdcc_init_data
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ljmp __sdcc_program_startup
\begin_inset Newline newline
\end_inset

__sdcc_init_data:
\end_layout

\begin_layout Verse

\family typewriter
\series bold
\size footnotesize
(crtxinit.asm)
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area GSINIT3 (CODE)
\begin_inset Newline newline
\end_inset

__mcs51_genXINIT::
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r1,#l_XINIT
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r1
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

orl a,#(l_XINIT >> 8)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

jz 00003$
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r2,#((l_XINIT+255) >> 8)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov dptr,#s_XINIT
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r0,#s_XISEG
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov __XPAGE,#(s_XISEG >> 8)
\begin_inset Newline newline
\end_inset

00001$:
\begin_inset space ~
\end_inset

clr a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

movc a,@a+dptr
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

movx @r0,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc dptr
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc r0
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

cjne r0,#0,00002$
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc __XPAGE
\begin_inset Newline newline
\end_inset

00002$:
\begin_inset space ~
\end_inset

djnz r1,00001$
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

djnz r2,00001$
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov __XPAGE,#0xFF
\begin_inset Newline newline
\end_inset

00003$:
\end_layout

\begin_layout Verse

\family typewriter
\series bold
\size footnotesize
(crtclear.asm)
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area GSINIT4 (CODE)
\begin_inset Newline newline
\end_inset

__mcs51_genRAMCLEAR::
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

clr a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r0,#(l_IRAM-1)
\begin_inset Newline newline
\end_inset

00004$:
\begin_inset space ~
\end_inset

mov @r0,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

djnz r0,00004$
\begin_inset Newline newline
\end_inset

;
 _mcs51_genRAMCLEAR() end
\end_layout

\begin_layout Verse

\family typewriter
\series bold
\size footnotesize
(crtxclear.asm)
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area GSINIT4 (CODE)
\begin_inset Newline newline
\end_inset

__mcs51_genXRAMCLEAR::
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r0,#l_PSEG
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r0
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

orl a,#(l_PSEG >> 8)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

jz 00006$
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r1,#s_PSEG
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov __XPAGE,#(s_PSEG >> 8)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

clr a
\begin_inset Newline newline
\end_inset

00005$:
\begin_inset space ~
\end_inset

movx @r1,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc r1
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

djnz r0,00005$
\begin_inset Newline newline
\end_inset

00006$:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r0,#l_XSEG
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r0
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

orl a,#(l_XSEG >> 8)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

jz 00008$
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r1,#((l_XSEG + 255) >> 8)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov dptr,#s_XSEG
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

clr a
\begin_inset Newline newline
\end_inset

00007$:
\begin_inset space ~
\end_inset

movx @dptr,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc dptr
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

djnz r0,00007$
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

djnz r1,00007$
\begin_inset Newline newline
\end_inset

00008$:
\end_layout

\begin_layout Verse

\family typewriter
\series bold
\size footnotesize
(crtxstack.asm)
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area GSINIT5 (CODE)
\begin_inset Newline newline
\end_inset

;
 Need to initialize in GSINIT5 because __mcs51_genXINIT modifies __XPAGE
\begin_inset Newline newline
\end_inset

;
 and __mcs51_genRAMCLEAR modifies _spx.
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov __XPAGE,#(__start__xstack >> 8)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov _spx,#__start__xstack
\end_layout

\begin_layout Verse

\family typewriter
\series bold
\size footnotesize
(application modules)
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area GSINIT (CODE)
\end_layout

\begin_layout Verse

\family typewriter
\series bold
\size footnotesize
(main.asm)
\end_layout

\begin_layout Verse

\family typewriter
\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area GSFINAL (CODE)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ljmp __sdcc_program_startup
\begin_inset Newline newline
\end_inset

;--------------------------------------------------------
\begin_inset Newline newline
\end_inset

;
 Home
\begin_inset Newline newline
\end_inset

;--------------------------------------------------------
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area HOME (CODE)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area CSEG (CODE)
\begin_inset Newline newline
\end_inset

__sdcc_program_startup:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

lcall _main
\begin_inset Newline newline
\end_inset

;
 return from main will lock up
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sjmp .
\end_layout

\begin_layout Standard
On some mcs51 variants __xdata
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

xdata (mcs51,
 ds390 named address space
\end_layout

\end_inset

 memory has to be explicitly enabled before it can be accessed or if the watchdog
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
watchdog
\end_layout

\end_inset

 needs to be disabled,
 this is the place to do it.
 The startup code clears all internal data memory,
 256 bytes by default,
 but from 0 to n-1 if 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-iram-size
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-iram-size <Value>
\end_layout

\end_inset

 <n>
\emph default
 is used.
 (recommended for Chipcon CC1010).
\end_layout

\begin_layout Standard
See also the compiler option 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-xinit
\emph default
-
\emph on
opt
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-xinit-opt
\end_layout

\end_inset

 and section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:MCS51-variants"
nolink "false"

\end_inset

 about MCS51-variants.
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
While these initialization modules are meant as generic startup code there might be the need for customization.
 Let's assume the return value of 
\emph on
__sdcc_external_startup()
\emph default
 in 
\emph on
crtstart.asm
\emph default
 should not be checked (or 
\emph on
__sdcc_external_startup()
\emph default
 should not be called at all).
 The recommended way would be to copy 
\emph on
crtstart.asm
\emph default
 (f.e.
 from 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://svn.code.sf.net/p/sdcc/code/trunk/sdcc/device/lib/mcs51/crtstart.asm
\end_layout

\end_inset

) into the source directory,
 adapt it there,
 then assemble it with 
\emph on
sdas8051 -plosgff
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
\begin_inset Quotes sld
\end_inset

-plosgff
\begin_inset Quotes srd
\end_inset

 are the assembler options used in 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.svn.sourceforge.net/viewvc/sdcc/trunk/sdcc/device/lib/mcs51/Makefile.in?view=markup 
\end_layout

\end_inset


\end_layout

\end_inset

 crtstart.asm
\emph default
 and when linking your project explicitly specify 
\emph on
crtstart.rel
\emph default
.
 As a bonus a listing of the relocated object file 
\emph on
crtstart.rst
\emph default
 is generated.
\end_layout

\begin_layout Subsection
Interfacing with Assembler Code
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Assembler routines
\end_layout

\end_inset


\end_layout

\begin_layout Subsubsection
Global Registers used for Parameter Passing
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Parameter passing
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The compiler always uses the global registers 
\emph on
DPL,
 DPH
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DPTR,
 DPH,
 DPL
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DPTR
\end_layout

\end_inset

,
 B
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
B (mcs51,
 ds390 register)
\end_layout

\end_inset


\emph default
 and 
\emph on
ACC
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
ACC (mcs51,
 ds390 register)
\end_layout

\end_inset


\emph default
 to pass the first (non-bit,
 non-struct) parameter to a function,
 and also to pass the return value 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
return value
\end_layout

\end_inset

of function;
 according to the following scheme:
 one byte return value in 
\emph on
DPL
\emph default
,
 two byte value in 
\emph on
DPL
\emph default
 (LSB) and 
\emph on
DPH
\emph default
 (MSB).
 three byte values (generic pointers) in 
\emph on
DPH
\emph default
,
 
\emph on
DPL
\emph default
 and 
\emph on
B
\emph default
,
 and four byte values in 
\emph on
DPH
\emph default
,
 
\emph on
DPL
\emph default
,
 
\emph on
B
\emph default
 and 
\emph on
ACC
\emph default
.
 Generic pointers
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
generic pointer
\end_layout

\end_inset

 contain type of accessed memory in 
\emph on
B
\emph default
:
 
\series bold
0x00
\series default
 – xdata/far,
 
\series bold
0x40
\series default
 – idata/near – ,
 
\series bold
0x60
\series default
 – pdata,
 
\series bold
0x80
\series default
 – code
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
This might not be the case of certain memory models (medium???)
\end_layout

\end_inset

.
\end_layout

\begin_layout Standard
Further such parameters (and all struct parameters,
 as well as the bit parameters from the 9th onwards) are either allocated on the stack (for reentrant routines or if -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-auto is used) or in data/xdata memory (depending on the memory model).
\end_layout

\begin_layout Standard
The first 8 bit parameters are passed in a virtual register called 'bits' in bit-addressable space for reentrant functions or allocated directly in bit memory otherwise.
\end_layout

\begin_layout Standard
Functions (with two or more parameters or bit parameters) that are called through function pointers
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
function pointers
\end_layout

\end_inset

 must therefor be reentrant so the compiler knows how to pass the parameters.
\end_layout

\begin_layout Subsubsection
Register usage
\end_layout

\begin_layout Standard
Unless the called function is declared as 
\family typewriter
_naked
\family default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
naked
\end_layout

\end_inset

,
 or the -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-callee-saves
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-callee-saves
\end_layout

\end_inset

/-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-all-callee-saves command line option or the corresponding callee_saves pragma are used,
 the caller will save the registers (
\emph on
R0-R7
\emph default
) around the call,
 so the called function can destroy they content freely.
\end_layout

\begin_layout Standard
If the called function is not declared as 
\family typewriter
_naked
\family default
,
 the caller will swap register banks around the call,
 if caller and callee use different register banks (having them defined by the 
\family typewriter
__using
\family default
 modifier).
 
\end_layout

\begin_layout Standard
The called function can also use 
\emph on
DPL
\emph default
,
 
\emph on
DPH
\emph default
,
 
\emph on
B
\emph default
 and 
\emph on
ACC
\emph default
 observing that they are used for parameter/return value passing.
\end_layout

\begin_layout Subsubsection
Assembler Routine (non-reentrant)
\end_layout

\begin_layout Standard
In the following example
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
reentrant
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Assembler routines (non-reentrant)
\end_layout

\end_inset

 the function c_func calls an assembler routine asm_func,
 which takes two parameters
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
function parameter
\end_layout

\end_inset

.
\end_layout

\begin_layout Verse

\family typewriter
extern int asm_func(unsigned char,
 unsigned char);
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

int c_func (unsigned char i,
 unsigned char j)
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return asm_func(i,j);
\begin_inset Newline newline
\end_inset

}
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

int main()
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return c_func(10,9);
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
The corresponding assembler function is:
\end_layout

\begin_layout Verse

\family typewriter
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.globl _asm_func_PARM_2
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.globl _asm_func
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area OSEG
\begin_inset Newline newline
\end_inset

_asm_func_PARM_2:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.ds    1
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.area CSEG
\begin_inset Newline newline
\end_inset

_asm_func:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,dpl
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,_asm_func_PARM_2
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dpl,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dph
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DPTR,
 DPH,
 DPL
\end_layout

\end_inset

,#0x00
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ret
\end_layout

\begin_layout Standard
The parameter naming convention is _<function_name>_PARM_<n>,
 where n is the parameter number starting from 1,
 and counting from the left.
 The first parameter is passed in 
\emph on
DPH
\emph default
,
 
\emph on
DPL
\emph default
,
 
\emph on
B
\emph default
 and 
\emph on
ACC
\emph default
 according to the description above.
 The variable name for the second parameter will be _<function_name>_PARM_2.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Assemble the assembler routine with the following command:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
sdas8051 -losg asmfunc.asm
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family default
\series default
Then compile and link the assembler routine to the C source file with the following command:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
sdcc cfunc.c asmfunc.rel
\end_layout

\begin_layout Subsubsection
Assembler Routine (reentrant)
\end_layout

\begin_layout Standard
In this case
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
reentrant
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Assembler routines (reentrant)
\end_layout

\end_inset

 the second parameter
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
function parameter
\end_layout

\end_inset

 onwards will be passed on the stack,
 the parameters are pushed from right to left i.e.
 before the call the second leftmost parameter will be on the top of the stack (the leftmost parameter is passed in registers).
 Here is an example:
\end_layout

\begin_layout Verse

\family typewriter
extern int asm_func(unsigned char,
 unsigned char,
 unsigned char) reentrant;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

int c_func (unsigned char i,
 unsigned char j,
 unsigned char k) reentrant 
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return asm_func(i,j,k);
\begin_inset Newline newline
\end_inset

}
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

int main()
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return c_func(10,9,8);
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
The corresponding (unoptimized) assembler routine is:
\end_layout

\begin_layout Verse

\family typewriter
.globl _asm_func
\begin_inset Newline newline
\end_inset

_asm_func:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

push
\begin_inset space ~
\end_inset

_bp
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

_bp,sp
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;stack contains:
 _bp,
 return address,
 second parameter,
 third parameter
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

r2,dpl
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,_bp
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,#0xfd
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;calculate pointer to the second parameter
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

r0,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,_bp
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,#0xfc
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;calculate pointer to the rightmost parameter
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

r1,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,@r0
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,@r1
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,r2
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;calculate the result (= sum of all three parameters)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dpl,a
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;return value goes into dptr (cast into int)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dph,#0x00
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sp,_bp
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

pop
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

_bp
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ret
\end_layout

\begin_layout Standard
The compiling and linking procedure remains the same,
 however note the extra entry & exit linkage required for the assembler code,
 _bp is the stack frame pointer and is used to compute the offset into the stack for parameters and local variables.
\end_layout

\begin_layout Section
DS400 port
\end_layout

\begin_layout Standard
The DS80C400
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS80C400
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DS400
\end_layout

\end_inset

 microcontroller has a rich set of peripherals.
 In its built-in ROM library it includes functions to access some of the features,
 among them is a TCP stack with IP4 and IP6 support.
 Library headers (currently in beta status) and other files are provided at 
\size footnotesize

\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

ftp://ftp.dalsemi.com/pub/tini/ds80c400/c_libraries/sdcc/index.html
\end_layout

\end_inset

.
 
\end_layout

\begin_layout Section
The Z80,
 Z180,
 Rabbit 2000,
 Rabbit 2000A,
 Rabbit 3000A,
 SM83 (GameBoy),
 eZ80,
 TLCS-90 and R800 ports
\end_layout

\begin_layout Standard
SDCC can target the Z80
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80
\end_layout

\end_inset

,
 Z180,
 eZ80 in Z80 mode,
 Rabbit 2000,
 Rabbit 2000A,
 Rabbit 3000A and LR35902,
 the Sharp SM83 (used .e.g in the Nintendo GameBoy) sm83
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
sm83 (GameBoy Z80)
\end_layout

\end_inset

.
\end_layout

\begin_layout Standard
When a frame pointer is used,
 it resides in IX.
 Register A,
 B,
 C,
 D,
 E,
 H,
 L and IY are used as a temporary registers for holding variables.
\end_layout

\begin_layout Standard
When enabling optimizations using 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--opt-code
\end_layout

\end_inset

 size and a sufficiently high value for 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--max-allocs-per-node
\end_layout

\end_inset

 SDCC typically generates much better code for these architectures than many other compilers.
 A comparison of compilers for these architecture can be found at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/wiki/index.php/Z80_code_size
\end_layout

\end_inset

.
\end_layout

\begin_layout Subsection
Startup Code
\end_layout

\begin_layout Standard
On the Z80
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Z80
\end_layout

\end_inset

 the startup code is inserted by linking with crt0.rel which is generated from sdcc/device/lib/z80/crt0.s.
 If you need a different startup code you can use the compiler option 
\emph on
-
\series bold
\emph default

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series default
\emph on
-no-std-crt0
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-std-crt0
\end_layout

\end_inset

 and provide your own crt0.rel.
 When using a custom crt0.rel it needs to be listed first when linking.
\end_layout

\begin_layout Subsection
Rabbit ports
\end_layout

\begin_layout Standard
SDCC has three Rabbit-supporting ports:
 r2k for the Rabbit 2000,
 r2ka for the Rabbit 2000A,
 2000B,
 2000C and 3000,
 r3ka for the Rabbit 3000A,
 4000 and 6000.
 Some Rabbits support different memory types (Rabbit 4000 and later),
 different memory access modes (Rabbit 5000 and later),
 different instruction modes (Rabbit 4000 and later).
 All SDCC ports assume 8-bit memories,
 8-bit memory access mode,
 00/default instruction set mode (the code generated is also compatible with 10 and 01 instruction set mode,
 but not 11/enhanced instruction set mode).
\end_layout

\begin_layout Subsubsection
Port choice
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="4" columns="10">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0pt">
<column alignment="center" valignment="top" width="0pt">
<column alignment="center" valignment="top" width="0pt">
<column alignment="center" valignment="top" width="0pt">
<column alignment="center" valignment="top" width="0pt">
<column alignment="center" valignment="top" width="0pt">
<column alignment="center" valignment="top" width="0pt">
<column alignment="center" valignment="top" width="0pt">
<column alignment="center" valignment="top" width="0pt">
<column alignment="center" valignment="top" width="0pt">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Ports vs.
 Device
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R2K
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R2kK
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R2KB
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R2KC
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R3K
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R3KA
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R4K
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R5K
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R6K
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
r2k
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Y
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
y
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
y
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
y
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
y
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
y
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
y
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\end_layout

\begin_layout Standard
Legend:
\end_layout

\begin_layout Standard
Y - The code this port generates is the best for this CPU.
\end_layout

\begin_layout Standard
y - The code this port generates will work on this CPU.
\end_layout

\begin_layout Standard
N - The code this port generates will not work on this CPU.
\end_layout

\begin_layout Standard
n - The code this port generates will typically not work on this CPU.
\end_layout

\begin_layout Standard
There are multiple wait state bugs present in some of the the Rabbits.
 The difference between the r2k and r2ka port is additional wait state bug workarounds.
 If all memory used has zero wait states,
 code from the r2ka backend can be safely run on the original Rabbit 2000.
\end_layout

\begin_layout Standard
The r2k and r2ka port assume that the whole stack has the same number of wait states (code from the r2k and r2ka ports can fail is the stack spans memories with a different amount of wait states).
\end_layout

\begin_layout Standard
The Rabbit 2000 has some wait state bugs that SDCC does not work around.
 These bugs result in the number of wait states used being one less than configured for some instructions.
 The workaround has to be supplied by the user,
 by configuring all memories that do use wait states to use on additional wait state.
\end_layout

\begin_layout Standard
For all Rabbit ports,
 SDCC assumes that all data memory is at least as fast (i.e.
 does not need more wait states) as all code memory.
 Code where this is not the case (e.g.
 code in fast Flash writing into slow battery-backed SRAM) will have to be written in assembler by hand.
\end_layout

\begin_layout Subsubsection
Rabbit hardware bugs
\end_layout

\begin_layout Standard
\begin_inset Tabular
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Bug
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ioi / ioe prefix bug
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ddcb / fdcb wait state bug
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conditional jump wait state bug
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ldir / lddr wait state bug
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mul wait state bug
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w
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ldir / lddr split bug
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S
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new ldir / lddr wait state bug
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w
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w
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w
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w
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16-bit mode alignment bug
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X
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<row>
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ioi / ioe bit bug
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\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
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\end_layout

\end_inset
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\end_layout

\end_inset
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x
\end_layout

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\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
ret cc bug
\end_layout

\end_inset
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\begin_layout Plain Layout

\end_layout

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<row>
<cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
rmw wait state bug
\end_layout

\end_inset
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\begin_inset Text

\begin_layout Plain Layout
W
\end_layout

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W
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W
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W
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\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
16-bit vs.
 8-bit wait state bug
\end_layout

\end_inset
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\end_layout

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W
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\end_inset
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</row>
<row>
<cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
dma vs stack prot.
 bug
\end_layout

\end_inset
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\begin_layout Plain Layout

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X
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<row>
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\begin_inset Text

\begin_layout Plain Layout
16-bit dma vs.
 ldir / lddr / etc.
 bug
\end_layout

\end_inset
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\begin_inset Text

\begin_layout Plain Layout

\end_layout

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\begin_layout Plain Layout

\end_layout

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\begin_layout Plain Layout

\end_layout

\end_inset
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<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
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<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
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<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
X
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
Legend:
\end_layout

\begin_layout Standard
x s w u - bug present,
 worked around by SDCC.
\end_layout

\begin_layout Standard
X S W U - bug present,
 not worked around by SDCC.
\end_layout

\begin_layout Standard
w W u U - wait state bug,
 only relevant when the Rabbit is configured to have wait states for some memory.
\end_layout

\begin_layout Standard
s S - instruction / data split bug,
 only relevant when instruction / data split is enabled,
 which is currently not supported by SDCC.
\end_layout

\begin_layout Standard
u U - bug can be worked around by the user by configuring memory that needs wait states to use one additional wait state.
\end_layout

\begin_layout Standard
The 16-bit mode alignment bug only affects 16-bit mode,
 which is not currently supported by SDCC.
\end_layout

\begin_layout Standard
The rmw wait state bug is only relevant when executing fast code writing to slow memory,
 such as code in fast RAM writing to slow battery-backed SRAM.
\end_layout

\begin_layout Standard
The 16-bit vs.
 8-bit wait state bug is only relevant when the target system uses both 16-bit and 8-bit memories for code,
 and the 8-bit memory requires wait states.
\end_layout

\begin_layout Standard
The 16-bit dma vs.
 ldir / lddr / etc.
 bug is only relevant when using DMA and the target system uses 16-bit memory for code.
 Since SDCC uses the block move instructions like ldir,
 lddr,
 etc.
 without applying a workaround,
 this means that code execution and DMA may then not happen at the same time.
 A possible user workaround is to not use DMA when using 16-bit memory for code.
 Among all Rabbit 4000-based RCM and BL modules,
 only the RCM4000 and the RCM4010 use 16-bit memories.
\end_layout

\begin_layout Standard
There are no documented Rabbit 6000 bugs,
 but Rabbit 6000 documentation in general is lacking compared to the other Rabbits.
\end_layout

\begin_layout Subsection
Z80,
 Z180,
 Z80N and R800 calling conventions
\end_layout

\begin_layout Standard
The current default is the SDCC calling convention,
 version 1.
 Using the command-line option –sdcccall 0,
 the default can be changed to version 0.
 There are three other calling conventions supported,
 which can be specified using the keywords __smallc,
 __z88dk_fastcall and __z88dk_callee.
 They are primarily intended for compatibility with libraries written for other compilers.
 For __z88dk_fastcall,
 there may be only one parameter of at most 32 bits,
 which is passed the same way as the return value of __sdcccall(0).
 For __z88dk_callee,
 the stack is not adjusted for stack parameters the parameters after the call (thus the callee has to do this instead).
 __z88dk_callee can be combined with __smallc,
 __sdcccall(0) or __sdcccall(1).
\end_layout

\begin_layout Subsubsection
Z80 SDCC calling convention,
 version 1
\end_layout

\begin_layout Standard
This calling convention can be chosen per function via __sdcccall(1).
 8-bit return values are passed in a,
 16-bit values in de,
 24-bit values in lde,
 32-bit values in hlde.
 Larger return values (as well as struct and union independent of their size) are passed in memory in a location specified by the caller through a hidden pointer argument.
\end_layout

\begin_layout Standard
For functions that have variable arguments:
 All parameters are passed on the stack.
 The stack is not adjusted for the parameters by the callee (thus the caller has to do this instead).
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename z80-arguments.svg

\end_inset


\end_layout

\begin_layout Standard
For Functions that do not have variable arguments:
 the first parameter is passed in a if it has 8 bits.
 If it has 16 bits it is passed in hl.
 If it has 32 bits,
 it is passed in hlde.
 If the first parameter is in a,
 and the second has 8 bits,
 it is passed in l;
 if the first is passed in a or hl,
 and the second has 16 bits,
 it is passed in de;
 all other parameters are passed on the stack,
 right-to-left.
 Independent of their size,
 struct / union parameters and all following parameters are always passed on the stack.
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename z80-stack-cleanup.svg

\end_inset


\end_layout

\begin_layout Standard
If __z88dk_callee is not used,
 after the call,
 the stack parameters are cleaned up by the caller,
 with the following exceptions:
 functions that do not have variable arguments and return void or a type of at most 16 bits,
 or have both a first parameter of type float and a return value of type float.
\end_layout

\begin_layout Subsubsection
Z80 SDCC calling convention,
 version 0
\end_layout

\begin_layout Standard
This calling convention can be chosen per function via __sdcccall(0).
 All parameters are passed on the stack,
 right-to-left.
 8-bit return values are passed in l,
 16-bit values in hl,
 24-bit values in ehl,
 32-bit values in dehl.
 Except for the SM83,
 where 8-bit values are passed in e,
 16-bit values in de,
 32-bit values in hlde.
 Larger return values (as well as struct and union independent of their size) are passed in a memory in a location specified by the caller through a hidden pointer argument.
 Unless __z88dk_callee is used,
 all stack parameters are cleaned up by the caller.
\end_layout

\begin_layout Subsection
Rabbit 2000,
 Rabbit 2000A,
 Rabbit 3000A,
 eZ80 and TLCS-90 calling conventions
\end_layout

\begin_layout Standard
The current default is the Rabbit calling convetion desribed here,
 version 1.
 Using the command-line option –sdcccall 8,
 the default can be changed to version 0 of the Z80 calling convention,
 described above.
 There are four other calling conventions supported,
 which can be specified using the keywords __smallc,
 __z88dk_fastcall and __z88dk_callee.
 They are primarily intended for compatibility with libraries written for other compilers.
 For __z88dk_fastcall,
 there may be only one parameter of at most 32 bits,
 which is passed the same way as the return value.
 For __z88dk_callee,
 the stack is not adjusted for stack parameters the parameters after the call (thus the callee has to do this instead).
 __z88dk_callee can be combined with __smallc,
 __sdcccall(0) or __sdcccall(1).
\end_layout

\begin_layout Subsubsection
Rabbit SDCC calling convention,
 version 1
\end_layout

\begin_layout Standard
This calling convention can be chosen per function via __sdcccall(1).
 8-bit return values are passed in a,
 16-bit values in hl,
 24-bit values in lde,
 32-bit values in hlde.
 Larger return values (as well as struct and union independent of their size) are passed in memory in a location specified by the caller through a hidden pointer argument.
\end_layout

\begin_layout Standard
For functions that have variable arguments:
 All parameters are passed on the stack.
 The stack is not adjusted for the parameters by the callee (thus the caller has to do this instead).
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename r3ka-arguments.svg

\end_inset


\end_layout

\begin_layout Standard
For Functions that do not have variable arguments:
 the first parameter is passed in a if it has 8 bits.
 If it has 16 bits it is passed in hl.
 If it has 32 bits,
 it is passed in hlde.
 If the first parameter is in a,
 and the second has 8 bits,
 it is passed in l;
 if the first is in hl or hlde,
 and the second has 8 bits,
 it is passed in a;
 if the first is in a,
 and the second has 16 bits,
 it is passed in hl;
 all other parameters are passed on the stack,
 right-to-left.
 Independent of their size,
 struct / union parameters and all following parameters are always passed on the stack.
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename z80-stack-cleanup.svg

\end_inset


\end_layout

\begin_layout Standard
If __z88dk_callee is not used,
 after the call,
 the stack parameters are cleaned up by the caller,
 with the following exceptions:
 functions that do not have variable arguments and return void or a type of at most 16 bits,
 or have both a first parameter of type float and a return value of type float.
\end_layout

\begin_layout Subsection
SM83 calling conventions
\end_layout

\begin_layout Standard
The current default is the SDCC calling convention,
 version 1.
 Using the command-line option –sdcccall 0,
 the default can be changed to version 0.
\end_layout

\begin_layout Subsubsection
SM83 SDCC calling convention,
 version 1
\end_layout

\begin_layout Standard
This calling convention can be chosen per function via __sdcccall(1).
\end_layout

\begin_layout Standard
8-bit return values are passed in a,
 16-bit values in bc,
 32-bit values in debc.
 Larger return values (as well as struct and union independent of their size) are passed in memory in a location specified by the caller through a hidden pointer argument.
\end_layout

\begin_layout Standard
For functions that have variable arguments:
 All parameters are passed on the stack.
 The stack is not adjusted for the parameters by the callee (thus the caller has to do this instead).
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename sm83-arguments.svg

\end_inset


\end_layout

\begin_layout Standard
For Functions that do not have variable arguments:
 the first parameter is passed in a if it has 8 bits.
 If it has 16 bits it is passed in de.
 If it has 32 bits,
 it is passed in debc.
 If the first parameter is in a,
 and the second has 8 bits,
 it is passed in e;
 if the first is in bc or debc,
 and the second has 8 bits,
 it is passed in a;
 if the first is passed in a,
 and the second has 16 bits,
 it is passed in bc;
 if the first is passed in de,
 and the second has 16 bits,
 it is passed in bc;
 all other parameters are passed on the stack,
 right-to-left.
 Independent of their size,
 struct / union parameters and all following parameters are always passed on the stack.
 The stack is adjusted by the callee (thus explicitly specifying __z88dk_callee does not make a difference),
 unless the functionhas variable arguments.
\end_layout

\begin_layout Subsubsection
SM83 SDCC calling convention,
 version 0
\end_layout

\begin_layout Standard
This calling convention can be chosen per function via __sdcccall(0).
 8-bit return values are passed in e,
 16-bit values in de,
 32-bit values in hlde.
 Larger return values (as well as struct and union independent of their size) are passed in memory in a location specified by the caller through a hidden pointer argument.
 All parameters are passed on the stack.
 The stack is not adjusted for the parameters by the callee (thus the caller has to do this instead),
 unless __z88dk_callee is specified.
 __sdcccall(0) can be combined with __z88dk_callee.
\end_layout

\begin_layout Subsection
Small-C calling convention
\end_layout

\begin_layout Standard
Functions declared as __smallc are called using the Small-C calling convention (passing arguments on-stack left-to-right,
 1 byte arguments are passed as 2 bytes,
 with the value in the lower byte).
 8-bit return values are passed in a,
 16-bit values in de,
 32-bit values in hlde.
 Larger return values (as well as struct and union independent of their size) are passed in memory in a location specified by the caller through a hidden pointer argument.
 This way assembler routines originally written for Small-C or code generated by Small-C can be called from SDCC.
 Currently variable arguments are not yet supported (neither on the caller nor on the callee side).
\end_layout

\begin_layout Subsection
Complex instructions
\end_layout

\begin_layout Standard
The Z80 and some derivatives support complex instructions,
 such as ldir,
 cpir,
 ...
 .
 SDCC only emits these instructions for functions in the standard library.
 Thus,
 e.g.
 copying one array into another is more efficient when using memcpy() than by using a a user-written loop.
\end_layout

\begin_layout Standard
Depending on the target,
 code generation options and the parameters to the call,
 SDCC emits ldir for memcpy(),
 ldir or lsidr for memset(),
 ldi for strcpy(),
 ldi for strncpy().
 Other library functions use the complex instructions as well,
 but for those,
 function calls are generated.
\end_layout

\begin_layout Subsection
Unsafe reads
\end_layout

\begin_layout Standard
Usually,
 Z80-based systems (except for the SM83 and TLCS-90) have separate I/O and memory spaces,
 and any normal memory location can be read without side-effects.
 For such systems,
 the option –allow-unsafe-reads can be used to enable some extra optimizations that rely on this.
\end_layout

\begin_layout Subsection
Z80 banked calls
\end_layout

\begin_layout Standard
Banked calls are supported via __banked.
 Banked calls are done via a trampoline (__sdcc_bcall if --legacy-banking is specified,
 __sdcc_bcall_abc for z88dk_fastcall,
 __sdcc_bcall_ehl for other calls).
 Default trampolines are provided in the library.
 The default trampolines calls user supplied helper functions set_bank and get_bank that set the current bank to the value in register a,
 or return the current bank in register a.
\end_layout

\begin_layout Standard
For banked functions,
 the calling convention is slightly different:
 the stack is always cleared up by the caller.
 Unless __z88dk_fastcall is used,
 all parameters are passed on the stack.
\end_layout

\begin_layout Section
The HC08 and S08 ports
\end_layout

\begin_layout Standard
The port to the Freescale/Motorola HC08
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
HC08
\end_layout

\end_inset

 and S08 does not yet generate code as compact as that generated by some non-free compilers.
 A comparison of compilers for these architecture can be found at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/wiki/index.php/Hc08_code_size
\end_layout

\end_inset

.
\end_layout

\begin_layout Subsection
Startup Code
\end_layout

\begin_layout Standard
The HC08
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
HC08
\end_layout

\end_inset

 startup code follows the same scheme as the MCS51 startup code.
\end_layout

\begin_layout Section
The STM8 port
\end_layout

\begin_layout Subsection
Calling conventions
\end_layout

\begin_layout Standard
By default,
 the SDCC calling convention,
 version 1 is used.
 Using the option –sdcccall 0,
 the default can be changed to version 0.
\end_layout

\begin_layout Standard
Arguments are passed on the stack right-to-left.
 Return values are in a (8 bit),
 x (16 bit),
 xyl (24 bit),
 xy (32 bit) or use a hidden extra pointer parameter pointing to the location (anything wider than 32 bit,
 and all struct / union).
\end_layout

\begin_layout Subsubsection
SDCC calling convention,
 version 1
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename stm8-arguments.svg

\end_inset


\end_layout

\begin_layout Standard
For functions that have variable arguments,
 all parameters are passed on the stack.
 For other functions,
 if the first parameter has 8 or 16 bits,
 it is passed in a or x.
 If the first parameter is passed in a,
 and the second has 16 bits,
 the second is passed in x.
 If the first parameter is passed in x,
 and the second has 8 bits,
 the second is passed in a.
 All other parameters are passed on the stack.
 Independent of their size,
 struct / union parameters and all following parameters are always passed on the stack.
 If __z88dk_callee is specified,
 the stack is always adjusted by the callee.
 Otherwise,
 for the large memory model,
 the stack is always adjusted by the caller.
 For the medium memory model the stack is adjusted by the caller,
 with the following exceptions:
 functions that do not have variable arguments and return void or a type of at most 16 bits,
 or have both a first parameter of type float and a return value of type float.
\end_layout

\begin_layout Subsubsection
SDCC calling convention,
 version 0
\end_layout

\begin_layout Standard
This calling convention can be chosen per function via __sdcccall(0) (e.g.
 for compatibility with functions written in assembler for use with older versions of SDCC).
 All parameters are passed on the stack.
 The stack is not adjusted for the parameters by the callee (thus the caller has to do this instead),
 unless __z88dk_callee is specified.
\end_layout

\begin_layout Subsubsection
Raisonance calling convention
\end_layout

\begin_layout Standard
For compatibility with the 
\lang british
Raisonance
\lang english
 STM8 compiler,
 the __raisonance calling convention is supported.
 If the first parameter is 8 or 16 bits,
 it is passed in a or x.
 If the first parameter is 8 bits,
 and the second 16 bits,
 the second is passed in x.
 If the first parameter is 16 bits,
 and the second is 8 bits,
 the second is passed in a.
 All other parameters are passed on the stack.
 If the return value is 8 bits,
 it is passed in a.
 If it is 16 bits,
 it is passed in x.
 Raisonance passes larger return values in pseudoregisters,
 which is not supported by SDCC.
\end_layout

\begin_layout Subsubsection
IAR calling convention
\end_layout

\begin_layout Standard
For compatibility with the IAR STM8 compiler,
 the __iar calling convention is supported.
 The first 8-bit parameter is passed in a,
 the first 16-bit parameter in x,
 the second 16-bit parameter in y.
 Further parameters of up to 32 bits are passed in pseudoregisters,
 which is not supported by SDCC.
 All other parameters are passed on the stack.
 If the return value is 8 bits,
 it is passed in a.
 If it is 16 bits,
 it is passed in x.
 IAR passes larger return values in pseudoregisters,
 which is not supported by SDCC.
\end_layout

\begin_layout Subsubsection
Cosmic calling convention
\end_layout

\begin_layout Standard
For compatibility with the Cosmic STM8 compiler,
 the __cosmic calling convention is supported.
 If the first parameter is 8 or 16 bits,
 it is passed in a or x.
 If the return value is 8 bits,
 it is passed in a.
 If it is 16 bits,
 it is passed in x.
 Cosmic passes larger return values in pseudoregisters,
 which is not supported by SDCC.
 Even for the medium memory model,
 __cosmic functions use a 24-bit return address in their stack frame,
 and are called using callf.
\end_layout

\begin_layout Section
The PIC14
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14
\end_layout

\end_inset

 port
\end_layout

\begin_layout Standard
The PIC14 port adds support for Microchip
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Microchip
\end_layout

\end_inset


\begin_inset Formula $^{\text{TM}}$
\end_inset

 PIC
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14
\end_layout

\end_inset


\begin_inset Formula $^{\text{TM}}$
\end_inset

 MCUs with 14 bit wide instructions.
 This port is not yet mature and still lacks many features.
 However,
 it can work for simple code.
\end_layout

\begin_layout Standard
\noindent
Currently supported devices include:
\end_layout

\begin_layout Standard
\begin_inset VSpace defskip
\end_inset


\end_layout

\begin_layout Standard
10F320,
 10F322,
 10LF320,
 10LF322
\end_layout

\begin_layout Standard
12F609,
 12F615,
 12F617,
 12F629,
 12F635,
 12F675,
 12F683
\end_layout

\begin_layout Standard
12F752
\end_layout

\begin_layout Standard
12HV752
\end_layout

\begin_layout Standard
16C62,
 16C63A,
 16C65B
\end_layout

\begin_layout Standard
16C71,
 16C72,
 16C73B,
 16C74B
\end_layout

\begin_layout Standard
16C432,
 16C433
\end_layout

\begin_layout Standard
16C554,
 16C557,
 16C558
\end_layout

\begin_layout Standard
16C620,
 16C620A,
 16C621,
 16C621A,
 16C622,
 16C622A
\end_layout

\begin_layout Standard
16C710,
 16C711,
 16C715,
 16C717,
 16C745,
 16C765,
 16C770,
 16C771,
 16C773,
 16C774,
 16C781,
 16C782
\end_layout

\begin_layout Standard
16C925,
 16C926 
\end_layout

\begin_layout Standard
16CR73,
 16CR74,
 16CR76,
 16CR77
\end_layout

\begin_layout Standard
16CR620A
\end_layout

\begin_layout Standard
16F72 ,16F73,
 16F74,
 16F76,
 16F77
\end_layout

\begin_layout Standard
16F84,
 16F84A,
 16F87,
 16F88
\end_layout

\begin_layout Standard
16F610,
 16F616,
 16F627,
 16F627A,
 16F628,
 16F628A,
 16F630,
 16F631,
 16F636,
 16F639,
 16F648A
\end_layout

\begin_layout Standard
16F676,
 16F677,
 16F684,
 16F685,
 16F687,
 16F688,
 16F689,
 16F690
\end_layout

\begin_layout Standard
16F707,
 16F716,
 16F720,
 16F721,
 16F722,
 16F722A,
 16F723,
 16F723A,
 16F724,
 16F726,
 16F727
\end_layout

\begin_layout Standard
16F737,
 16F747,
 16F753,
 16F767,
 16F777,
 16F785
\end_layout

\begin_layout Standard
16F818,
 16F819,
 16F870,
 16F871,
 16F872,
 16F873,
 16F873A,
 16F874,
 16F874A,
 16F876,
 16F876A
\end_layout

\begin_layout Standard
16F877,
 16F877A,
 16F882,
 16F883,
 16F884,
 16F886,
 16F887
\end_layout

\begin_layout Standard
16F913,
 16F914,
 16F916,
 16F917,
 16F946
\end_layout

\begin_layout Standard
16LF74,
 16LF76,
 16LF77
\end_layout

\begin_layout Standard
16LF84,
 16LF84A,
 16LF87,
 16LF88
\end_layout

\begin_layout Standard
16LF627,
 16LF627A,
 16LF628,
 16LF628A,
 16LF648A
\end_layout

\begin_layout Standard
16LF707,
 16LF720,
 16LF721,
 16LF722,
 16LF722A,
 16LF723,
 16LF723A,
 16LF724,
 16LF726,
 16LF727 
\end_layout

\begin_layout Standard
16LF747,
 16LF767,
 16LF777
\end_layout

\begin_layout Standard
16LF818,
 16LF819,
 16LF870,
 16LF871,
 16LF872,
 16LF873,
 16LF873A,
 16LF874,
 16LF874A
\end_layout

\begin_layout Standard
16LF876,
 16LF876A,
 16LF877,
 16LF877A
\end_layout

\begin_layout Standard
16HV610,
 16HV616,
 16HV753,
 16HV785
\end_layout

\begin_layout Standard
\begin_inset VSpace defskip
\end_inset


\end_layout

\begin_layout Standard
\noindent
\align left
Supported devices with enhanced cores:
\end_layout

\begin_layout Standard
\begin_inset VSpace defskip
\end_inset


\end_layout

\begin_layout Standard
12F1501,
 12F1571,
 12F1572,
 12F1612,
 12F1822,
 12F1840
\end_layout

\begin_layout Standard
12LF1501,
 12LF1552,
 12LF1571,
 12LF1572,
 12LF1612,
 12LF1822,
 12LF1840,
 12LF1840T39A,
 12LF1840T48A
\end_layout

\begin_layout Standard
16F1454,
 16F1455,
 16F1458,
 16F1459
\end_layout

\begin_layout Standard
16F1503,
 16F1507,
 16F1508,
 16F1509,
 16F1512,
 16F1513,
 16F1516,
 16F1517,
 16F1518,
 16F1519
\end_layout

\begin_layout Standard
16F1526,
 16F1527,
 16F1574,
 16F1575,
 16F1578,
 16F1579
\end_layout

\begin_layout Standard
16F1613,
 16F1614,
 16F1615,
 16F1618,
 16F1619
\end_layout

\begin_layout Standard
16F1703,
 16F1704,
 16F1705,
 16F1707,
 16F1708,
 16F1709,
 16F1713,
 16F1716,
 16F1717,
 16F1718,
 16F1719
\end_layout

\begin_layout Standard
16F1764,
 16F1765,
 16F1768,
 16F1769,
 16F1773,
 16F1776,
 16F1777,
 16F1778,
 16F1779
\end_layout

\begin_layout Standard
16F1782,
 16F1783,
 16F1784,
 16F1786,
 16F1787,
 16F1788,
 16F1789
\end_layout

\begin_layout Standard
16F1823,
 16F1824,
 16F1825,
 16F1826,
 16F1827,
 16F1828,
 16F1829,
 16F1829LIN,
 16F1847
\end_layout

\begin_layout Standard
16F1933,
 16F1934,
 16F1936,
 16F1937,
 16F1938,
 16F1939,
 16F1946,
 16F1947
\end_layout

\begin_layout Standard
16F18313,
 16F18323,
 16F18324,
 16F18325,
 16F18344,
 16F18345,
\end_layout

\begin_layout Standard
16F18855,
 16F18875
\end_layout

\begin_layout Standard
16LF1454,
 16LF1455,
 16LF1458,
 16LF1459
\end_layout

\begin_layout Standard
16LF1503,
 16LF1507,
 16LF1508,
 16LF1509,
 16LF1512,
 16LF1513,
 16LF1516,
 16LF1517,
 16LF1518,
 16LF1519,
\end_layout

\begin_layout Standard
16LF1526,
 16LF1527 
\end_layout

\begin_layout Standard
16LF1554,
 16LF1559,
 16LF1566,
 16LF1567,
 16LF1574,
 16LF1575,
 16LF1578,
 16LF1579
\end_layout

\begin_layout Standard
16LF1613,
 16LF1614,
 16LF1615,
 16LF1618,
 16LF1619
\end_layout

\begin_layout Standard
16LF1703,
 16LF1704,
 16LF1705,
 16LF1707,
 16LF1708,
 16LF1709,
 16LF1713,
 16LF1716,
 16LF1717,
 16LF1718,
 16LF1719 
\end_layout

\begin_layout Standard
16LF1764,
 16LF1765,
 16LF1768,
 16LF1769,
 16LF1773,
 16LF1776,
 16LF1777,
 16LF1778,
 16LF1779
\end_layout

\begin_layout Standard
16LF1782,
 16LF1783,
 16LF1784,
 16LF1786,
 16LF1787,
 16LF1788,
 16LF1789,
\end_layout

\begin_layout Standard
16LF1823,
 16LF1824,
 16LF1824T39A
\end_layout

\begin_layout Standard
16LF1825,
 16LF1826,
 16LF1827,
 16LF1828,
 16LF1829,
 16LF1847
\end_layout

\begin_layout Standard
16LF1902,
 16LF1903,
 16LF1904,
 16LF1906,
 16LF1907
\end_layout

\begin_layout Standard
16LF1933,
 16LF1934,
 16LF1936,
 16LF1937,
 16LF1938,
 16LF1939,
 16LF1946,
 16LF1947
\end_layout

\begin_layout Standard
16LF18313,
 16LF18323,
 16LF18324,
 16LF18325,
 16LF18344,
 16LF18345
\end_layout

\begin_layout Standard
16LF18855,
 16LF18875
\end_layout

\begin_layout Standard
\begin_inset VSpace defskip
\end_inset


\end_layout

\begin_layout Standard
\noindent
An up-to-date list of currently supported devices can be obtained via 
\family typewriter
sdcc -mpic14 -phelp foo.c
\family default
 (foo.c must exist...).
\end_layout

\begin_layout Subsection
PIC Code Pages
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
code page (pic14)
\end_layout

\end_inset

 and Memory Banks
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Memory bank (pic14)
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The linker organizes allocation for the code page and RAM banks.
 It does not have intimate knowledge of the code flow.
 It will put all the code section of a single .asm file into a single code page.
 In order to make use of multiple code pages,
 separate asm files must be used.
 The compiler assigns all 
\emph on
static
\emph default
 functions of a single .c file into the same code page.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

To get the best results,
 follow these guidelines:
\end_layout

\begin_layout Enumerate
Make local functions static,
 as non static functions require code page selection overhead.
\begin_inset Newline newline
\end_inset

Due to the way SDCC handles functions,
 place called functions prior to calling functions in the file wherever possible:
 Otherwise SDCC will insert unnecessary pagesel directives around the call,
 believing that the called function is externally defined.
\end_layout

\begin_layout Enumerate
For devices that have multiple code pages it is more efficient to use the same number of files as pages:
 Use up to 4 separate .c files for the 16F877,
 but only 2 files for the 16F874.
 This way the linker can put the code for each file into different code pages and there will be less page selection overhead.
\end_layout

\begin_layout Enumerate
And as for any 8 bit micro (especially for PIC14 as they have a very simple instruction set),
 use `unsigned char' wherever possible instead of `int'.
\end_layout

\begin_layout Subsection
Adding New Devices to the Port 
\end_layout

\begin_layout Standard
Adding support for a new 14
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
,
\end_layout

\end_inset

bit PIC MCU requires the following steps:
\end_layout

\begin_layout Enumerate
Create a new device description.
\begin_inset Newline newline
\end_inset

Each device is described in two files:
 pic16f*.h and pic16f*.c.
 These files primarily define SFRs,
 structs to access their bits,
 and symbolic configuration options.
 Both files can be generated from gputils' .inc files using the perl script 
\family typewriter
support/scripts/inc2h.pl
\family default
.
 This file also contains further instructions on how to proceed.
\end_layout

\begin_layout Enumerate
Copy the .h file into SDCC's include path and either add the .c file to your project or copy it to 
\family typewriter
device/lib/pic/libdev
\family default
.
 Afterwards,
 rebuild and install the libraries.
\end_layout

\begin_layout Enumerate
Edit pic14devices.txt in SDCC's include path (
\family typewriter
device/include/pic/
\family default
 in the source tree or 
\family typewriter
/usr/local/share/sdcc/include/pic
\family default
 after installation).
\begin_inset Newline newline
\end_inset

You need to add a device specification here to make the memory layout (code banks,
 RAM,
 aliased memory regions,
 ...) known to the compiler.
 Probably you can copy and modify an existing entry.
 The file format is documented at the top of the file.
\end_layout

\begin_layout Subsection
Interrupt Code
\end_layout

\begin_layout Standard
For the interrupt function,
 use the keyword 
\emph on
__interrupt
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14!interrupt
\end_layout

\end_inset

 with level number of 0 (PIC14 only has 1 interrupt so this number is only there to avoid a syntax error - it ought to be fixed).
 E.g.:
\end_layout

\begin_layout Verse

\family typewriter
void Intr(void) __interrupt (0)
\begin_inset Newline newline
\end_inset

{
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

T0IF = 0;
 /* Clear timer interrupt */
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Subsection
Configuration Bits
\end_layout

\begin_layout Standard
Configuration bits (also known as fuses) can be configured using `
\family typewriter
__code
\family default
' and `
\family typewriter
__at
\family default
' modifiers.
 Possible options should be ANDed and can be found in your processor header file.
 Example for PIC16F88:
\end_layout

\begin_layout LyX-Code

\family typewriter
#include <pic16f88.h> //Contains config addresses and options
\begin_inset Newline newline
\end_inset

#include <stdint.h> //Needed for uint16_t
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

static __code uint16_t __at (_CONFIG1) configword1 = _INTRC_IO &
\begin_inset Newline newline
\end_inset

  _CP_ALL & _WDT_OFF & [...];
\begin_inset Newline newline
\end_inset

static __code uint16_t __at (_CONFIG2) configword2 = [...];
\end_layout

\begin_layout Standard
Although data type is ignored if the address (
\family typewriter
__at()
\family default
) refers to a config word location,
 using a type large enough for the configuration word (
\family typewriter
uint16_t
\family default
 in this case) is recommended to prevent changes in the compiler (implicit,
 early range check and enforcement) from breaking the definition.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

If your processor header file doesn't contain config addresses you can declare it manually or use a literal address:
\end_layout

\begin_layout LyX-Code

\family typewriter
static __code uint16_t __at (0x2007) configword1 = _INTRC_IO &
\begin_inset Newline newline
\end_inset

  _CP_ALL & _WDT_OFF & [...];
\end_layout

\begin_layout Subsection
Linking and Assembling
\end_layout

\begin_layout Standard
For assembling you can use either GPUTILS'
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
gputils (pic tools)
\end_layout

\end_inset

 gpasm.exe or MPLAB's mpasmwin.exe.
 GPUTILS are available from 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/projects/gputils
\end_layout

\end_inset

.
 For linking you can use either GPUTILS' gplink or MPLAB's mplink.exe.
 If you use MPLAB and an interrupt function then the linker script file vectors section will need to be enlarged to link with mplink.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Pic device specific header and c source files are automatically generated from MPLAB include files,
 which are published by Microchip with a special requirement that they are only to be used with authentic Microchip devices.
 This reqirement prevents to publish generated header and c source files under the GPL compatible license,
 so they are located in non-free directory (see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Search-Paths"
nolink "false"

\end_inset

).
 In order to include them in include and library search paths,
 the 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\end_layout

\end_inset


\series default
 command line option should be defined.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

NOTE:
 the compiled code,
 which use non-free pic device specific libraries,
 is not GPL compatible!
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Here is a 
\family typewriter
Makefile
\family default
 using GPUTILS:
\end_layout

\begin_layout Verse

\family typewriter
.c.o:
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcc -V --use-non-free -mpic14 -p16f877 -c $<
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

$(PRJ).hex:
 $(OBJS)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

gplink -m -s $(PRJ).lkr -o $(PRJ).hex $(OBJS) libsdcc.lib
\end_layout

\begin_layout Standard
Here is a 
\family typewriter
Makefile
\family default
 using MPLAB:
\end_layout

\begin_layout Verse

\family typewriter
.c.o:
 
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcc -S -V --use-non-free -mpic14 -p16f877 $<
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mpasmwin /q /o $*.asm
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

$(PRJ).hex:
 $(OBJS)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mplink /v $(PRJ).lkr /m $(PRJ).map /o $(PRJ).hex $(OBJS) libsdcc.lib
\end_layout

\begin_layout Standard
Please note that indentations within a 
\family typewriter
Makefile
\family default
 have to be done with a tabulator character.
\end_layout

\begin_layout Subsection
Command-Line Options
\end_layout

\begin_layout Standard
Besides the switches common to all SDCC backends,
 the PIC14 port accepts the following options (for an updated list see sdcc -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-help):
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug-xtra
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug-extra
\end_layout

\end_inset

 emit debug info in assembly output
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-pcode-opt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-pcode-opt
\end_layout

\end_inset

 disable (slightly faulty) optimization on pCode
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-loc
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-loc
\end_layout

\end_inset

 sets the lowest address of the argument passing stack (defaults to a suitably large shared databank to reduce BANKSEL overhead)
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-size
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-stack-size
\end_layout

\end_inset

 sets the size if the argument passing stack (default:
 16,
 minimum:
 4)
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\end_layout

\end_inset

 make non-free device headers and libraries available in the compiler's search paths (implicit -I and -L options)
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-extended-instructions forbid use of the extended instruction set (e.g.,
 ADDFSR)
\end_layout

\begin_layout Subsection
Environment Variables
\end_layout

\begin_layout Standard
The PIC14 port recognizes the following environment variables:
\end_layout

\begin_layout Description
SDCC_PIC14_SPLIT_LOCALS
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14!Environment variables!SDCC
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

PIC14
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

SPLIT
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

LOCALS
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Environment variables!SDCC
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

PIC14
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

SPLIT
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

LOCALS
\end_layout

\end_inset

 If set and not empty,
 sdcc will allocate each temporary register (the ones called r0xNNNN) in a section of its own.
 By default (if this variable is unset),
 sdcc tries to cluster registers in sections in order to reduce the BANKSEL overhead when accessing them.
\end_layout

\begin_layout Subsection
The Library
\end_layout

\begin_layout Standard
The PIC14 library currently only contains support routines required by the compiler to implement multiplication,
 division,
 and floating point support.
 No libc-like replacement is available at the moment,
 though many of the common sdcc library sources (in 
\family typewriter
device/lib
\family default
) should also compile with the PIC14 port.
\end_layout

\begin_layout Subsubsection
Enhanced cores
\end_layout

\begin_layout Standard
SDCC/PIC14 has experimental support for devices with the enhanced 14-bit cores (such as pic12f1822).
 Due to differences in required code,
 the libraries provided with SDCC (
\family typewriter
libm.lib
\family default
 and 
\family typewriter
libsdcc.lib
\family default
) are now provided in two variants:
 
\family typewriter
libm.lib
\family default
 and 
\family typewriter
libsdcc.lib
\family default
 are compiled for the regular,
 non-enhanced devices.
 
\family typewriter
libme.lib
\family default
 and 
\family typewriter
libsdcce.lib
\family default
 (note the trailing '
\family typewriter
e
\family default
') are compiled for enhanced devices.
 When linking manually,
 make sure to select the proper variant!
\end_layout

\begin_layout Standard
When SDCC is used to invoke the linker,
 SDCC will automatically select the 
\family typewriter
libsdcc.lib
\family default
-variant suitable for the target device.
 However,
 no such magic has been conjured up for 
\family typewriter
libm.lib
\family default
!
\end_layout

\begin_layout Subsubsection
Accessing bits of special function registers
\end_layout

\begin_layout Standard
Individual bits within SFRs can be accessed either using 
\family typewriter
<sfrname>bits.<bitname>
\family default
 or using a shorthand 
\family typewriter
<bitname>
\family default
,
 which is defined in the respective device header for all 
\family typewriter
<bitname>
\family default
s.
 In order to avoid polluting the global namespace with the names of all the bits,
 you can 
\family typewriter
#define NO_BIT_DEFINES
\family default
 before inclusion of the device header file.
\end_layout

\begin_layout Subsubsection
Naming of special function registers
\begin_inset CommandInset label
LatexCommand label
name "subsec:Naming-of-special"

\end_inset


\end_layout

\begin_layout Standard
If 
\family typewriter
NO_BIT_DEFINES
\family default
 is used,
 individual bits of the SFRs can be accessed as 
\family typewriter
<sfrname>bits.<bitname>
\family default
.
 With the 3.1.0 release,
 the previously used 
\family typewriter
<sfrname>_bits.<bitname>
\family default
 (note the underscore) is deprecated.
 This was done to align the naming conventions with the PIC16 port and competing compiler vendors.
 To avoid polluting the global namespace with the legacy names,
 you can prevent their definition using 
\family typewriter
#define NO_LEGACY_NAMES
\family default
 prior to the inclusion of the device header.
\end_layout

\begin_layout Standard
You 
\family typewriter
\series bold
must
\family default
\series default
 also 
\family typewriter
#define NO_BIT_DEFINES
\family default
 in order to access SFRs as 
\family typewriter
<sfrname>bits.<bitname>
\family default
,
 otherwise 
\family typewriter
<bitname>
\family default
 will expand to 
\family typewriter
<sfrname>bits.<bitname>
\family default
,
 yielding the undefined expression 
\family typewriter
<sfrname>bits.<sfrname>bits.<bitname>
\family default
.
\end_layout

\begin_layout Subsubsection
error:
 missing definition for symbol ``__gptrget1''
\end_layout

\begin_layout Standard
The PIC14 port uses library routines to provide more complex operations like multiplication,
 division/modulus and (generic) pointer dereferencing.
 In order to add these routines to your project,
 you must link with PIC14's 
\family typewriter
libsdcc.lib
\family default
.
 For single source file projects this is done automatically,
 more complex projects must add 
\family typewriter
libsdcc.lib
\family default
 to the linker's arguments.
 Make sure you also add an include path for the library (using the -I switch to the linker)!
\end_layout

\begin_layout Subsubsection
Processor mismatch in file ``XXX''.
\end_layout

\begin_layout Standard
This warning can usually be ignored due to the very good compatibility amongst 14
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
,
\end_layout

\end_inset

bit PIC
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC14
\end_layout

\end_inset

 devices.
\end_layout

\begin_layout Standard
You might also consider recompiling the library for your specific device by changing the ARCH=p16f877 (default target) entry in 
\family typewriter
device/lib/pic/Makefile.in
\family default
 and 
\family typewriter
device/lib/pic/Makefile
\family default
 to reflect your device.
 This might even improve performance for smaller devices as unnecessary BANKSELs might be removed.
\end_layout

\begin_layout Subsection
Known Bugs
\end_layout

\begin_layout Subsubsection
Function arguments
\end_layout

\begin_layout Standard
Functions with variable argument lists (like printf) are not yet supported.
 Similarly,
 taking the address of the first argument passed into a function does not work:
 It is currently passed in WREG and has no address...
\end_layout

\begin_layout Subsubsection
Regression tests fail
\end_layout

\begin_layout Standard
Though the small subset of regression tests in src/regression passes,
 SDCC regression test suite does not,
 indicating that there are still major bugs in the port.
 However,
 many smaller projects have successfully used SDCC in the past...
\end_layout

\begin_layout Section
The PIC16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16
\end_layout

\end_inset

 port
\end_layout

\begin_layout Standard
The PIC16 port adds support for Microchip
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Microchip
\end_layout

\end_inset


\begin_inset Formula $^{\text{TM}}$
\end_inset

 PIC
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC
\end_layout

\end_inset


\begin_inset Formula $^{\text{TM}}$
\end_inset

 MCUs with 16 bit wide instructions.
 This port is not yet mature and still lacks many features.
 However,
 it can work for simple code.
 Currently this family of microcontrollers contains the PIC18Fxxx and PIC18Fxxxx;
 devices supported by the port include:
\end_layout

\begin_layout Standard
\begin_inset VSpace defskip
\end_inset


\end_layout

\begin_layout Standard
18F13K22 18F13K50
\end_layout

\begin_layout Standard
18F14K22 18F14K50
\end_layout

\begin_layout Standard
18F23K20 18F23K22
\end_layout

\begin_layout Standard
18F24J10 18F24J11 18F24J50 18F24K20 18F24K22 18F24K50
\end_layout

\begin_layout Standard
18F25J10 18F25J11 18F25J50 18F25K20 18F25K22 18F25K50 18F25K80
\end_layout

\begin_layout Standard
18F26J11 18F26J13 18F26J50 18F26J53 18F26K20 18F26K22 18F26K80
\end_layout

\begin_layout Standard
18F27J13 18F27J53
\end_layout

\begin_layout Standard
18F43K20 18F43K22
\end_layout

\begin_layout Standard
18F44J10 18F44J11 18F44J50 18F44K20 18F44K22
\end_layout

\begin_layout Standard
18F45J10 18F45J11 18F45J50 18F45K20 18F45K22 18F45K50 18F45K80
\end_layout

\begin_layout Standard
18F46J11 18F46J13 18F46J50 18F46J53 18F46K20 18F46K22 18F46K80
\end_layout

\begin_layout Standard
18F47J13 18F47J53
\end_layout

\begin_layout Standard
18F63J11 18F63J90
\end_layout

\begin_layout Standard
18F64J11 18F64J90
\end_layout

\begin_layout Standard
18F65J10 18F65J11 18F65J15 18F65J50 18F65J90 18F65J94 18F65K22 18F65K80 18F65K90
\end_layout

\begin_layout Standard
18F66J10 18F66J11 18F66J15 18F66J16 18F66J50 18F66J55 18F66J60 18F66J65
\end_layout

\begin_layout Standard
18F66J90 18F66J93 18F66J94 18F66J99 18F66K22 18F66K80 18F66K90
\end_layout

\begin_layout Standard
18F67J10 18F67J11 18F67J50 18F67J60 18F67J90 18F67J93 18F67J94 18F67K22 18F67K90
\end_layout

\begin_layout Standard
18F83J11 18F83J90
\end_layout

\begin_layout Standard
18F84J11 18F84J90
\end_layout

\begin_layout Standard
18F85J10 18F85J11 18F85J15 18F85J50 18F85J90 18F85J94 18F85K22 18F85K90
\end_layout

\begin_layout Standard
18F86J10 18F86J11 18F86J15 18F86J16 18F86J50 18F86J55 18F86J60 18F86J65
\end_layout

\begin_layout Standard
18F86J72 18F86J90 18F86J93 18F86J94 18F86J99 18F86K22 18F86K90
\end_layout

\begin_layout Standard
18F87J10 18F87J11 18F87J50 18F87J60 18F87J72 18F87J90 18F87J93 18F87J94 18F87K22 18F87K90
\end_layout

\begin_layout Standard
18F95J94 18F96J60 18F96J65 18F96J94 18F96J99
\end_layout

\begin_layout Standard
18F97J60 18F97J94
\end_layout

\begin_layout Standard
18F242 18F248 18F252 18F258
\end_layout

\begin_layout Standard
18F442 18F448 18F452 18F458
\end_layout

\begin_layout Standard
18F1220 18F1230
\end_layout

\begin_layout Standard
18F1320 18F1330
\end_layout

\begin_layout Standard
18F2220 18F2221
\end_layout

\begin_layout Standard
18F2320 18F2321 18F2331
\end_layout

\begin_layout Standard
18F2410 18F2420 18F2423 18F2431 18F2439 18F2450 18F2455 18F2458 18F2480
\end_layout

\begin_layout Standard
18F2510 18F2515 18F2520 18F2523 18F2525 18F2539 18F2550 18F2553 18F2580 18F2585
\end_layout

\begin_layout Standard
18F2610 18F2620 18F2680 18F2682 18F2685
\end_layout

\begin_layout Standard
18F4220 18F4221
\end_layout

\begin_layout Standard
18F4320 18F4321 18F4331
\end_layout

\begin_layout Standard
18F4410 18F4420 18F4423 18F4431 18F4439 18F4450 18F4455 18F4458 18F4480
\end_layout

\begin_layout Standard
18F4510 18F4515 18F4520 18F4523 18F4525 18F4539 18F4550 18F4553 18F4580 18F4585
\end_layout

\begin_layout Standard
18F4610 18F4620 18F4680 18F4682 18F4685
\end_layout

\begin_layout Standard
18F6310 18F6390 18F6393
\end_layout

\begin_layout Standard
18F6410 18F6490 18F6493
\end_layout

\begin_layout Standard
18F6520 18F6525 18F6527 18F6585
\end_layout

\begin_layout Standard
18F6620 18F6621 18F6622 18F6627 18F6628 18F6680
\end_layout

\begin_layout Standard
18F6720 18F6722 18F6723
\end_layout

\begin_layout Standard
18F8310 18F8390 18F8393
\end_layout

\begin_layout Standard
18F8410 18F8490 18F8493
\end_layout

\begin_layout Standard
18F8520 18F8525 18F8527 18F8585
\end_layout

\begin_layout Standard
18F8620 18F8621 18F8622 18F8627 18F8628 18F8680
\end_layout

\begin_layout Standard
18F8720 18F8722 18F8723
\end_layout

\begin_layout Standard
18LF13K22 18LF13K50
\end_layout

\begin_layout Standard
18LF14K22 18LF14K50
\end_layout

\begin_layout Standard
18LF23K22 18LF24J10 18LF24J11 18LF24J50 18LF24K22 18LF24K50
\end_layout

\begin_layout Standard
18LF25J10 18LF25J11 18LF25J50 18LF25K22 18LF25K50 18LF25K80
\end_layout

\begin_layout Standard
18LF26J11 18LF26J13 18LF26J50 18LF26J53 18LF26K22 18LF26K80
\end_layout

\begin_layout Standard
18LF27J13 18LF27J53
\end_layout

\begin_layout Standard
18LF43K22
\end_layout

\begin_layout Standard
18LF44J10 18LF44J11 18LF44J50 18LF44K22
\end_layout

\begin_layout Standard
18LF45J10 18LF45J11 18LF45J50 18LF45K22 18LF45K50 18LF45K80
\end_layout

\begin_layout Standard
18LF46J11 18LF46J13 18LF46J50 18LF46J53 18LF46K22 18LF46K80
\end_layout

\begin_layout Standard
18LF47J13 18LF47J53
\end_layout

\begin_layout Standard
18LF65K80
\end_layout

\begin_layout Standard
18LF66K80
\end_layout

\begin_layout Standard
18LF242 18LF248 18LF252 18LF258
\end_layout

\begin_layout Standard
18LF442 18LF448 18LF452 18LF458
\end_layout

\begin_layout Standard
18LF1220 18LF1230
\end_layout

\begin_layout Standard
18LF1320 18LF1330
\end_layout

\begin_layout Standard
18LF2220 18LF2221
\end_layout

\begin_layout Standard
18LF2320 18LF2321 18LF2331
\end_layout

\begin_layout Standard
18LF2410 18LF2420 18LF2423 18LF2431 18LF2439 18LF2450 18LF2455 18LF2458 18LF2480
\end_layout

\begin_layout Standard
18LF2510 18LF2515 18LF2520 18LF2523 18LF2525 18LF2539 18LF2550 18LF2553 18LF2580 18LF2585
\end_layout

\begin_layout Standard
18LF2610 18LF2620 18LF2680 18LF2682 18LF2685
\end_layout

\begin_layout Standard
18LF4220 18LF4221
\end_layout

\begin_layout Standard
18LF4320 18LF4321 18LF4331
\end_layout

\begin_layout Standard
18LF4410 18LF4420 18LF4423 18LF4431 18LF4439 18LF4450 18LF4455 18LF4458 18LF4480
\end_layout

\begin_layout Standard
18LF4510 18LF4515 18LF4520 18LF4523 18LF4525 18LF4539 18LF4550 18LF4553 18LF4580 18LF4585
\end_layout

\begin_layout Standard
18LF4610 18LF4620 18LF4680 18LF4682 18LF4685
\end_layout

\begin_layout Standard
18LF6310 18LF6390 18LF6393
\end_layout

\begin_layout Standard
18LF6410 18LF6490 18LF6493
\end_layout

\begin_layout Standard
18LF6520 18LF6525 18LF6527 18LF6585
\end_layout

\begin_layout Standard
18LF6620 18LF6621 18LF6622 18LF6627 18LF6628 18LF6680
\end_layout

\begin_layout Standard
18LF6720 18LF6722 18LF6723
\end_layout

\begin_layout Standard
18LF8310 18LF8390 18LF8393
\end_layout

\begin_layout Standard
18LF8410 18LF8490 18LF8493
\end_layout

\begin_layout Standard
18LF8520 18LF8525 18LF8527 18LF8585
\end_layout

\begin_layout Standard
18LF8620 18LF8621 18LF8622 18LF8627 18LF8628 18LF8680
\end_layout

\begin_layout Standard
18LF8720 18LF8722 18LF8723 
\end_layout

\begin_layout Standard
\begin_inset VSpace defskip
\end_inset


\end_layout

\begin_layout Standard
\noindent
An up-to-date list of supported devices is also available via '
\family typewriter
sdcc -mpic16 -plist
\family default
'.
\end_layout

\begin_layout Subsection
Global Options
\end_layout

\begin_layout Standard
PIC16 port supports the standard command line arguments as supposed,
 with the exception of certain cases that will be mentioned in the following list:
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-callee-saves
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-callee-saves
\end_layout

\end_inset

 See -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-all-callee-saves
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Options!-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\end_layout

\end_inset

 Make non-free device headers and libraries available in the compiler's search paths (implicit -I and -L options).
\end_layout

\begin_layout Subsection
Port Specific Options
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Options PIC16
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The port specific options appear after the global options in the sdcc -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-help output.
\end_layout

\begin_layout Subsubsection
Code Generation Options
\end_layout

\begin_layout Standard
These options influence the generated assembler code.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-pstack-model=[model] Used in conjunction with the command above.
 Defines the stack model to be used,
 valid stack models are:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_deeper
\begin_layout Labeling
\labelwidthstring 00.00.0000

\emph on
small
\emph default
 Selects small stack model.
 8 bit stack and frame pointers.
 Supports 256 bytes stack size.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\emph on
large
\emph default
 Selects large stack model.
 16 bit stack and frame pointers.
 Supports 65536 bytes stack size.
\end_layout

\end_deeper
\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-pno-banksel Do not generate BANKSEL assembler directives.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-extended Enable extended instruction set/literal offset addressing mode.
 Use with care!
\end_layout

\begin_layout Subsubsection
Optimization Options
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-obanksel=n Set optimization level for inserting BANKSELs.
\begin_inset Newline newline
\end_inset


\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_deeper
\begin_layout Labeling
\labelwidthstring 00.00.0000
0 no optimization
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
1 checks previous used register and if it is the same then does not emit BANKSEL,
 accounts only for labels.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
2 tries to check the location of (even different) symbols and removes BANKSELs if they are in the same bank.
 
\begin_inset Newline newline
\end_inset


\emph on
Important:
 There might be problems if the linker script has data sections across bank borders!
\end_layout

\end_deeper
\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-denable-peeps Force the usage of peepholes.
 Use with care.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-optimize-goto Do not use (conditional) BRA instead of GOTO.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-optimize-cmp Try to optimize some compares.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-optimize-df Analyze the dataflow of the generated code and improve it.
\end_layout

\begin_layout Subsubsection
Assembling Options
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-asm= Sets the full path and name of an external assembler to call.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-mplab-comp MPLAB
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!MPLAB
\end_layout

\end_inset

 compatibility option.
 Currently only suppresses special gpasm directives.
\end_layout

\begin_layout Subsubsection
Linking Options
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-link= Sets the full path and name of an external linker to call.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-preplace-udata-with=[kword] Replaces the default udata keyword for allocating unitialized data variables with [kword].
 Valid keywords are:
 "udata_acs",
 "udata_shr",
 "udata_ovr".
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-ivt-loc=n Place the interrupt vector table at address 
\emph on
n
\emph default
.
 Useful for bootloaders.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-nodefaultlibs Do not link default libraries when linking.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-crt= Use a custom run-time module instead of the default (crt0i).
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-crt Don't link the default run-time modules
\end_layout

\begin_layout Subsubsection
Debugging Options
\end_layout

\begin_layout Standard
Debugging options enable extra debugging information in the output files.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug-xtra Similar to -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug
\end_layout

\end_inset

,
 but dumps more information.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug-ralloc Force register allocator to dump <source>.d file with debugging information.
 <source> is the name of the file being compiled.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-pcode-verbose Enable pcode debugging information in translation.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-calltree Dump call tree in .calltree file.
\end_layout

\begin_layout Description
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-gstack Trace push/pops for stack pointer overflow.
\end_layout

\begin_layout Subsection
Environment Variables
\end_layout

\begin_layout Standard
There is a number of environmental variables that can be used when running SDCC to enable certain optimizations or force a specific program behaviour.
 these variables are primarily for debugging purposes so they can be enabled/disabled at will.
\end_layout

\begin_layout Standard
Currently there is only two such variables available:
\end_layout

\begin_layout Description
OPTIMIZE_BITFIELD_POINTER_GET
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Environment variables!OPTIMIZE
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

BITFIELD
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

POINTER
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

GET
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Environment variables!OPTIMIZE
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

BITFIELD
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

POINTER
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

GET (PIC16)
\end_layout

\end_inset

 When this variable exists,
 reading of structure bit-fields is optimized by directly loading FSR0 with the address of the bit-field structure.
 Normally SDCC will cast the bit-field structure to a bit-field pointer and then load FSR0.
 This step saves data ram and code space for functions that make heavy use of bit-fields.
 (i.e.,
 80 bytes of code space are saved when compiling malloc.c with this option).
 
\end_layout

\begin_layout Description
NO_REG_OPT
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Environment variables!NO
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

REG
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

OPT
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Environment variables!NO
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

REG
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

OPT
\end_layout

\end_inset

 Do not perform pCode registers optimization.
 This should be used for debugging purposes.
 If bugs in the pcode optimizer are found,
 users can benefit from temporarily disabling the optimizer until the bug is fixed.
\end_layout

\begin_layout Subsection
Preprocessor Macros
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Preprocessor!PIC16 Macros
\end_layout

\end_inset


\end_layout

\begin_layout Standard
PIC16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16
\end_layout

\end_inset

 port defines the following preprocessor macros while translating a source.
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="5" columns="2">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Macro
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Description
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
__SDCC_pic16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC!Defines!__SDCC
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

pic16
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Port identification
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
pic18fxxxx
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Defines!pic18fxxxx
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
MCU Identification.
 
\emph on
xxxx
\emph default
 is the microcontrol identification number,
 i.e.
 452,
 6620,
 etc
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
_
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

_18Fxxxx
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Defines!
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset


\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

pic18fxxxx
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
MCU Identification (same as above)
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
STACK_MODEL_nnn
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Defines!STACK
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

MODEL
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

nnn
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
nnn = SMALL or LARGE respectively according to the stack model used
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
\noindent
In addition the following macros are defined when calling assembler:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="4" columns="2">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Macro
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Description
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
__18Fxxxx
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
MCU Identification.
 
\emph on
xxxx
\emph default
 is the microcontrol identification number,
 i.e.
 452,
 6620,
 etc
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
__SDCC_MODEL_nnn
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
nnn = SMALL or LARGE respectively according to the memory model used for SDCC
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
STACK_MODEL_nnn
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
nnn = SMALL or LARGE respectively according to the stack model used
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Subsection
Directories
\end_layout

\begin_layout Standard
PIC16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16
\end_layout

\end_inset

 port uses the following directories for searching header files and libraries.
\begin_inset Newline newline
\end_inset


\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="4">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Directory
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Description
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Target
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Command prefix
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PREFIX/sdcc/include/pic16
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PIC16 specific headers
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Compiler
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
-I
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PREFIX/sdcc/lib/pic16
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PIC16 specific libraries
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Linker
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
-L
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
If the 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\end_layout

\end_inset


\series default
 command line option is specified,
 non-free directories are searched:
\begin_inset Newline newline
\end_inset


\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="4">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Directory
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Description
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Target
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Command prefix
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PREFIX/sdcc/non-free/include/pic16
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PIC16 specific non-free headers
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Compiler
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
-I
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PREFIX/sdcc/non-free/lib/pic16
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PIC16 specific non-free libraries
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Linker
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
-L
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Subsection
Pragmas
\begin_inset CommandInset label
LatexCommand label
name "subsec:PIC16_Pragmas"

\end_inset


\end_layout

\begin_layout Standard
The PIC16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16
\end_layout

\end_inset

 port currently supports the following pragmas:
\end_layout

\begin_layout Description
stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Pragmas!
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma stack
\end_layout

\end_inset

 This forces the code generator to initialize the stack & frame pointers at a specific address.
 This is an ad hoc solution for cases where no STACK directive is available in the linker script or gplink is not instructed to create a stack section.
\begin_inset Newline newline
\end_inset

The stack pragma should be used only once in a project.
 Multiple pragmas may result in indeterminate behaviour of the program.
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
The old format (ie.
 #pragma stack 0x5ff) is deprecated and will cause the stack pointer to cross page boundaries (or even exceed the available data RAM) and crash the program.
 Make sure that stack does not cross page boundaries when using the SMALL stack model.
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset

The format is as follows:
\end_layout

\begin_layout LyX-Code
#pragma stack bottom_address [stack_size]
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard

\emph on
bottom_address
\emph default
 is the lower bound of the stack section.
 The stack pointer initially will point at address (bottom_address+stack_size-1).
\end_layout

\begin_layout LyX-Code
Example:
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout LyX-Code
/* initializes stack of 100 bytes at RAM address 0x200 */
\end_layout

\begin_layout LyX-Code
#pragma stack 0x200 100
\end_layout

\begin_layout Standard
If the stack_size field is omitted then a stack is created with the default size of 64.
 This size might be enough for most programs,
 but its not enough for operations with deep function nesting or excessive stack usage.
\end_layout

\begin_layout Description
code
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Pragmas!
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma code
\end_layout

\end_inset

 Force a function to a static FLASH address.
\end_layout

\begin_layout LyX-Code
Example:
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout LyX-Code
/* place function test_func at 0x4000 */
\end_layout

\begin_layout LyX-Code
#pragma code test_func 0x4000
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout Description
library
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Pragmas!
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma library
\end_layout

\end_inset

 instructs the linker to use a library module.
\begin_inset Newline newline
\end_inset

Usage:
\end_layout

\begin_layout LyX-Code
#pragma library module_name
\end_layout

\begin_layout Standard

\emph on
module_name
\emph default
 can be any library or object file (including its path).
 Note that there are four reserved keywords which have special meaning.
 These are:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="6" columns="3">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="block" valignment="top" width="20page%">
<column alignment="left" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Keyword
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Description
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Module to link
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
ignore
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
ignore all library pragmas
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\emph on
(none)
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
c
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
link the C library
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\emph on
libc18f
\emph default
.lib
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
math
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
link the Math libarary
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\emph on
libm18f
\emph default
.lib
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
io
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
link the I/O library
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\emph on
libio18f*
\emph default
.lib
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
debug
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
link the debug library
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\emph on
libdebug
\emph default
.lib
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\begin_inset Newline newline
\end_inset

* is the device number,
 i.e.
 452 for PIC18F452 MCU.
\end_layout

\begin_layout Standard
\noindent
This feature allows for linking with specific libraries without having to explicit name them in the command line.
 Note that the 
\noun on
ignore
\noun default
 keyword will reject all modules specified by the library pragma.
\end_layout

\begin_layout Description
udata
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Pragmas!
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma udata
\end_layout

\end_inset

 The pragma udata instructs the compiler to emit code so that linker will place a variable at a specific memory bank.
\end_layout

\begin_layout LyX-Code
Example:
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout LyX-Code
/* places variable foo at bank2 */
\end_layout

\begin_layout LyX-Code
#pragma udata bank2 foo
\end_layout

\begin_layout LyX-Code
char foo;
\end_layout

\begin_layout Standard
In order for this pragma to work extra SECTION directives should be added in the .lkr script.
 In the following example a sample .lkr file is shown:
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout LyX-Code
// Sample linker script for the PIC18F452 processor
\end_layout

\begin_layout LyX-Code
LIBPATH .
\end_layout

\begin_layout LyX-Code
CODEPAGE   NAME=vectors    START=0x0            END=0x29           PROTECTED
\end_layout

\begin_layout LyX-Code
CODEPAGE   NAME=page       START=0x2A           END=0x7FFF
\end_layout

\begin_layout LyX-Code
CODEPAGE   NAME=idlocs     START=0x200000       END=0x200007       PROTECTED
\end_layout

\begin_layout LyX-Code
CODEPAGE   NAME=config     START=0x300000       END=0x30000D       PROTECTED
\end_layout

\begin_layout LyX-Code
CODEPAGE   NAME=devid      START=0x3FFFFE       END=0x3FFFFF       PROTECTED
\end_layout

\begin_layout LyX-Code
CODEPAGE   NAME=eedata     START=0xF00000       END=0xF000FF       PROTECTED
\end_layout

\begin_layout LyX-Code
ACCESSBANK NAME=accessram  START=0x0            END=0x7F
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout LyX-Code
DATABANK   NAME=gpr0       START=0x80           END=0xFF
\end_layout

\begin_layout LyX-Code
DATABANK   NAME=gpr1       START=0x100          END=0x1FF
\end_layout

\begin_layout LyX-Code
DATABANK   NAME=gpr2       START=0x200          END=0x2FF
\end_layout

\begin_layout LyX-Code
DATABANK   NAME=gpr3       START=0x300          END=0x3FF
\end_layout

\begin_layout LyX-Code
DATABANK   NAME=gpr4       START=0x400          END=0x4FF
\end_layout

\begin_layout LyX-Code
DATABANK   NAME=gpr5       START=0x500          END=0x5FF
\end_layout

\begin_layout LyX-Code
ACCESSBANK NAME=accesssfr  START=0xF80          END=0xFFF          PROTECTED
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout LyX-Code
SECTION    NAME=CONFIG     ROM=config
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout LyX-Code
SECTION    NAME=bank0      RAM=gpr0       # these SECTION directives
\end_layout

\begin_layout LyX-Code
SECTION    NAME=bank1      RAM=gpr1       # should be added to link
\end_layout

\begin_layout LyX-Code
SECTION    NAME=bank2      RAM=gpr2       # section name 'bank?' with
\end_layout

\begin_layout LyX-Code
SECTION    NAME=bank3      RAM=gpr3       # a specific DATABANK name
\end_layout

\begin_layout LyX-Code
SECTION    NAME=bank4      RAM=gpr4
\end_layout

\begin_layout LyX-Code
SECTION    NAME=bank5      RAM=gpr5
\end_layout

\begin_layout Standard
The linker will recognise the section name set in the pragma statement and will position the variable at the memory bank set with the RAM field at the SECTION line in the linker script file.
\end_layout

\begin_layout Description
config
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Pragmas!
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma config
\end_layout

\end_inset

 The pragma config instructs the compiler to emit config directive.
\begin_inset Newline newline
\end_inset

The format is as follows:
\end_layout

\begin_layout LyX-Code
#pragma config setting=value [,
 setting=value]
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout Standard
Multiple settings may be defined on a single line,
 separated by commas.
 Settings for a single configuration byte may also be defined on separate lines.
 
\end_layout

\begin_layout LyX-Code
Example:
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout LyX-Code
#pragma config CP0=OFF,OSCS=ON,OSC=LP,BOR=ON,BORV=25,WDT=ON,WDTPS=128,CCP2MUX=ON
\end_layout

\begin_layout LyX-Code
#pragma config STVR=ON 
\end_layout

\begin_layout Subsection
Header Files and Libraries
\begin_inset CommandInset label
LatexCommand label
name "subsec:PIC16_Header-Files-and-Libraries"

\end_inset


\end_layout

\begin_layout Standard
Pic device specific header and c source files are automatically generated from MPLAB include files,
 which are published by Microchip with a special requirement that they are only to be used with authentic Microchip devices.
 This requirement prevents to publish generated header and c source files under the GPL compatible license,
 so they are located in the non-free directory (see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Search-Paths"
nolink "false"

\end_inset

).
 In order to include them in include and library search paths,
 the 
\series bold
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-use-non-free
\end_layout

\end_inset


\series default
 command line option should be defined.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

NOTE:
 the compiled code,
 which use non-free pic device specific libraries,
 is not GPL compatible!
\end_layout

\begin_layout Subsection
Header Files
\begin_inset CommandInset label
LatexCommand label
name "subsec:PIC16_Header-Files"

\end_inset


\end_layout

\begin_layout Standard
There is one main header file
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Header files
\end_layout

\end_inset

 that can be included to the source files using the pic16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16
\end_layout

\end_inset

 port.
 That file is the 
\series bold
pic18fregs.h
\series default
.
 This header file contains the definitions for the processor special registers,
 so it is necessary if the source accesses them.
 It can be included by adding the following line in the beginning of the file:
\end_layout

\begin_layout LyX-Code
#include <pic18fregs.h>
\end_layout

\begin_layout Standard
The specific microcontroller is selected within the pic18fregs.h automatically,
 so the same source can be used with a variety of devices.
\end_layout

\begin_layout Subsection
Libraries
\begin_inset CommandInset label
LatexCommand label
name "subsec:pic16Libraries"

\end_inset


\end_layout

\begin_layout Standard
The libraries
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!Libraries
\end_layout

\end_inset

 that PIC16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16
\end_layout

\end_inset

 port depends on are the microcontroller device libraries which contain the symbol definitions for the microcontroller special function registers.
 These libraries have the format pic18fxxxx.lib,
 where 
\emph on
xxxx
\emph default
 is the microcontroller identification number.
 The specific library is selected automatically by the compiler at link stage according to the selected device.
\end_layout

\begin_layout Standard
\noindent
Libraries are created with gplib which is part of the gputils package 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/projects/gputils
\end_layout

\end_inset

.
\end_layout

\begin_layout Subsubsection*
Building the libraries
\end_layout

\begin_layout Standard
Before using SDCC/pic16 there are some libraries that need to be compiled.
 This process is done automatically if gputils are found at SDCC's compile time.
 Should you require to rebuild the pic16 libraries manually (e.g.
 in order to enable output of float values
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
printf()!PIC16 Floating point support
\end_layout

\end_inset

 via 
\family typewriter
printf()
\family default
,
 see below),
 these are the steps required to do so under Linux or Mac OS X (cygwin might work as well,
 but is untested):
\end_layout

\begin_layout LyX-Code
cd device/lib/pic16
\end_layout

\begin_layout LyX-Code
./configure.gnu
\end_layout

\begin_layout LyX-Code
cd ..
\end_layout

\begin_layout LyX-Code
make model-pic16
\end_layout

\begin_layout LyX-Code
su -c 'make install'     # install the libraries,
 you need the root password
\end_layout

\begin_layout LyX-Code
cd ../..
\end_layout

\begin_layout Standard
If you need to install the headers too,
 do:
\end_layout

\begin_layout LyX-Code
cd device/include
\end_layout

\begin_layout LyX-Code
su -c 'make install'     # install the headers,
 you need the root password
\end_layout

\begin_layout Subsubsection*
Output of float values via printf()
\end_layout

\begin_layout Standard
The library is normally built without support for displaying float values,
 only <NO FLOAT>
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<NO FLOAT>
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
printf()!PIC16 floating point support
\end_layout

\end_inset

 will appear instead of the value.
 To change this,
 rebuild the library as stated above,
 but call 
\family typewriter
./configure.gnu --enable-floats 
\family default
instead of just 
\family typewriter
./configure.gnu
\family default
.
 Also make sure that at least 
\family typewriter
libc/stdio/vfprintf.c
\family default
 is actually recompiled,
 e.g.
 by 
\family typewriter
touch
\family default
ing it after the 
\family typewriter
configure
\family default
 run or deleting its 
\family typewriter
.o
\family default
 file.
\end_layout

\begin_layout Standard
The more common approach of compiling 
\family typewriter
vfprintf.c
\family default
 manually with 
\family typewriter
-DUSE_FLOATS=1
\family default
 should also work,
 but is untested.
\end_layout

\begin_layout Subsection
Adding New Devices to the Port
\end_layout

\begin_layout Standard
Adding support for a new 16
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
,
\end_layout

\end_inset

bit PIC MCU requires the following steps:
\end_layout

\begin_layout Enumerate
Create picDEVICE.c and picDEVICE.h from pDEVICE.inc using
\begin_inset Newline newline
\end_inset


\family typewriter
perl /path/to/sdcc/support/scripts/inc2h-pic16.pl 
\backslash

\begin_inset Newline newline
\end_inset

/path/to/gputils/header/pDEVICE.inc
\end_layout

\begin_layout Enumerate

\family typewriter
mv picDEVICE.h /path/to/sdcc/device/non-free/include/pic16
\end_layout

\begin_layout Enumerate

\family typewriter
mv picDEVICE.c /path/to/sdcc/device/non-free/lib/pic16/libdev
\end_layout

\begin_layout Enumerate
Either
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_deeper
\begin_layout Enumerate
add the new device to 
\family typewriter
/path/to/sdcc/device/lib/pic16/libio/*.ignore
\family default
 to suppress building any of the I/O libraries for the new device
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
In fact,
 the 
\family typewriter
.ignore
\family default
 files are only used when auto-generating 
\family typewriter
Makefile.am
\family default
 using the 
\family typewriter
.../libio/mkmk.sh
\family default
 script.
\end_layout

\end_inset

,
 or
\end_layout

\begin_layout Enumerate
add the device (family) to 
\family typewriter
/path/to/sdcc/support/scripts/pic18fam-h-gen.pl
\family default
 to assign I/O styles,
 run the 
\family typewriter
pic18fam-h-gen.pl
\family default
 script to generate 
\family typewriter
pic18fam.h.gen
\family default
,
 replace your existing 
\family typewriter
pic18fam.h
\family default
 with the generated file,
 and (if required) implement new I/O styles in 
\family typewriter
/path/to/sdcc/device/include/pic16/{adc,i2c,usart}.h
\family default
 and 
\family typewriter
/path/to/sdcc/device/lib/pic16/libio/*/*.
\end_layout

\end_deeper
\begin_layout Enumerate
Edit 
\family typewriter
/path/to/sdcc/device/include/pic16/pic18fregs.h
\family default

\begin_inset Newline newline
\end_inset

The file format is self-explanatory,
 just add
\begin_inset Newline newline
\end_inset


\family typewriter
#elif defined(picDEVICE)
\begin_inset Newline newline
\end_inset

#
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
 
\backslash
 
\end_layout

\end_inset

include <picDEVICE.h>
\family default

\begin_inset Newline newline
\end_inset

at the right place (keep the file sorted,
 please).
\end_layout

\begin_layout Enumerate
Edit 
\family typewriter
/path/to/sdcc/device/include/pic16devices.txt
\begin_inset Newline newline
\end_inset


\family default
Copy and modify an existing entry or create a new one and insert it at the correct place (keep the file sorted,
 please).
\end_layout

\begin_layout Enumerate

\family typewriter
( cd /path/to/sdcc/device/non-free/lib/pic16 && sh update.sh )
\end_layout

\begin_layout Enumerate
Recompile the pic16 libraries as described in 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:pic16Libraries"
nolink "false"

\end_inset

 or just configure and build sdcc again from scratch (recommended).
\end_layout

\begin_layout Subsection
Memory Models
\end_layout

\begin_layout Standard
The following memory models are supported by the PIC16 port:
\end_layout

\begin_layout Itemize
small model
\end_layout

\begin_layout Itemize
large model
\end_layout

\begin_layout Standard
Memory model affects the default size of pointers within the source.
 The sizes are shown in the next table:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="3">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Pointer sizes according to memory model
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
small model
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
large model
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
code pointers
\end_layout

\end_inset
</cell>
<cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
16-bits
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
24-bits
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
data pointers
\end_layout

\end_inset
</cell>
<cell multicolumn="1" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
16-bits
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
16-bits
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
It is advisable that all sources within a project are compiled with the same memory model.
 If one wants to override the default memory model,
 this can be done by declaring a pointer as 
\series bold
far
\series default
 or 
\series bold
near
\series default
.
 Far selects large memory model's pointers,
 while near selects small memory model's pointers.
\end_layout

\begin_layout Standard
The standard device libraries (see 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:PIC16_Header-Files"
nolink "false"

\end_inset

) contain no reference to pointers,
 so they can be used with both memory models.
\end_layout

\begin_layout Subsection
Stack
\end_layout

\begin_layout Standard
The stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!stack
\end_layout

\end_inset

 implementation for the PIC16 port uses two indirect registers,
 FSR1 and FSR2.
\end_layout

\begin_layout Description
FSR1 is assigned as stack pointer
\end_layout

\begin_layout Description
FSR2 is assigned as frame pointer
\end_layout

\begin_layout Standard
The following stack models are supported by the PIC16 port
\end_layout

\begin_layout Itemize

\noun on
small
\noun default
 model
\end_layout

\begin_layout Itemize

\noun on
large
\noun default
 model
\end_layout

\begin_layout Standard

\noun on
Small
\noun default
 model means that only the FSRxL byte is used to access stack and frame,
 while 
\emph on
\noun on
large
\emph default
\noun default
 uses both FSRxL and FSRxH registers.
 The following table shows the stack/frame pointers sizes according to stack model and the maximum space they can address:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="3">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Stack & Frame pointer sizes according to stack model
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
small
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
large
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Stack pointer FSR1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
8-bits
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
16-bits
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Frame pointer FSR2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
8-bits
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
16-bits
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
\noindent

\noun on
Large 
\noun default
stack model is currently not working properly throughout the code generator.
 So its use is not advised.
 Also there are some other points that need special care:
\end_layout

\begin_layout Enumerate
Do not create stack sections with size more than one physical bank (that is 256 bytes)
\end_layout

\begin_layout Enumerate
Stack sections should no cross physical bank limits (i.e.
 #pragma stack 0x50 0x100)
\end_layout

\begin_layout Standard
These limitations are caused by the fact that only FSRxL is modified when using SMALL stack model,
 so no more than 256 bytes of stack can be used.
 This problem will disappear after LARGE model is fully implemented.
\end_layout

\begin_layout Subsection
Functions
\end_layout

\begin_layout Standard
In addition to the standard SDCC function keywords,
 PIC16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16
\end_layout

\end_inset

 port makes available two more:
\end_layout

\begin_layout Description
__wparam
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!wparam
\end_layout

\end_inset

 Use the WREG to pass one byte of the first function argument.
 This improves speed but you may not use this for functions with arguments that are called via function pointers,
 otherwise the first byte of the first parameter will get lost.
 Usage:
\end_layout

\begin_layout LyX-Code
void func_wparam(int a) __wparam
\end_layout

\begin_layout LyX-Code
{
\end_layout

\begin_layout LyX-Code
    /* WREG hold the lower part of a */
\end_layout

\begin_layout LyX-Code
    /* the high part of a is stored in FSR2+2 (or +3 for large stack model) */
\end_layout

\begin_layout LyX-Code
...
\end_layout

\begin_layout LyX-Code
}
\end_layout

\begin_layout Description
__shadowregs
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!shadowregs
\end_layout

\end_inset

 When entering/exiting an ISR,
 it is possible to take advantage of the PIC18F hardware shadow registers which hold the values of WREG,
 STATUS and BSR registers.
 This can be done by adding the keyword 
\emph on
__shadowregs
\emph default
 before the 
\emph on
__interrupt
\emph default
 keyword in the function's header.
\end_layout

\begin_layout LyX-Code
void isr_shadow(void) __shadowregs __interrupt (1)
\end_layout

\begin_layout LyX-Code
{
\end_layout

\begin_layout LyX-Code
...
\end_layout

\begin_layout LyX-Code
}
\end_layout

\begin_layout Standard

\emph on
__shadowregs
\emph default
 instructs the code generator not to store/restore WREG,
 STATUS,
 BSR when entering/exiting the ISR.
\end_layout

\begin_layout Subsection
Function return values
\end_layout

\begin_layout Standard
Return values from functions are placed to the appropriate registers following a modified Microchip policy optimized for SDCC.
 The following table shows these registers:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="6" columns="2">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
size
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
destination register
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
8 bits
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
WREG
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
16 bits
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PRODL:WREG
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
24 bits
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PRODH:PRODL:WREG
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
32 bits
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
FSR0L:PRODH:PRODL:WREG
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
>32 bits
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
on stack,
 FSR0 points to the beginning
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Subsection
Interrupts
\end_layout

\begin_layout Standard
An interrupt
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!interrupt
\end_layout

\end_inset

 service routine (ISR) is declared using the 
\emph on
__interrupt
\emph default
 keyword.
\end_layout

\begin_layout LyX-Code
void isr(void) __interrupt 
\emph on
(n)
\end_layout

\begin_layout LyX-Code
{
\end_layout

\begin_layout LyX-Code
...
\end_layout

\begin_layout LyX-Code
}
\end_layout

\begin_layout Standard

\emph on
n
\emph default
 is the interrupt number,
 which for PIC18F devices can be:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="4" columns="3">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\emph on
n
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interrupt Vector
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Interrupt Vector Address
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
RESET vector
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0x000000
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
HIGH priority interrupts
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0x000008
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
LOW priority interrupts
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0x000018
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
When generating assembly code for ISR the code generator places a 
\noun on
goto 
\noun default
instruction at the 
\emph on
Interrupt Vector Address
\emph default
 which points at the generated ISR.
 This single GOTO instruction is part of an automatically generated 
\emph on
interrupt entry point
\emph default
 function.
 The actual ISR code is placed as normally would in the code space.
 Upon interrupt request,
 the GOTO instruction is executed which jumps to the ISR code.
 When declaring interrupt functions as _naked this GOTO instruction is 
\series bold
not
\series default
 generated.
 The whole interrupt functions is therefore placed at the Interrupt Vector Address of the specific interrupt.
 This is not a problem for the LOW priority interrupts,
 but it is a problem for the RESET and the HIGH priority interrupts because code may be written at the next interrupt's vector address and cause indeterminate program behaviour if that interrupt is raised.
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
This is not a problem when
\end_layout

\begin_layout Enumerate
this is a HIGH interrupt ISR and LOW interrupts are 
\emph on
disabled
\emph default
 or not used.
\end_layout

\begin_layout Enumerate
when the ISR is small enough not to reach the next interrupt's vector address.
\end_layout

\end_inset


\end_layout

\begin_layout Standard

\emph on
n
\emph default
 may be omitted.
 This way a function is generated similar to an ISR,
 but it is not assigned to any interrupt.
\end_layout

\begin_layout Standard
When entering an interrupt,
 currently the PIC16
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16
\end_layout

\end_inset

 port automatically saves the following registers:
\end_layout

\begin_layout Itemize
WREG
\end_layout

\begin_layout Itemize
STATUS
\end_layout

\begin_layout Itemize
BSR
\end_layout

\begin_layout Itemize
PROD (PRODL and PRODH)
\end_layout

\begin_layout Itemize
FSR0 (FSR0L and FSR0H)
\end_layout

\begin_layout Standard
These registers are restored upon return from the interrupt routine.
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
NOTE that when the _naked attribute is specified for an interrupt routine,
 then NO registers are stored or restored.
\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Generic Pointers
\end_layout

\begin_layout Standard
Generic pointers are implemented in PIC16 port as 3-byte (24-bit) types.
 There are 3 types of generic pointers currently implemented data,
 code and eeprom pointers.
 They are differentiated by the value of the 7th and 6th bits of the upper byte:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="5" columns="5">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="left" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
pointer type
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
7th bit
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
6th bit
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
rest of the pointer
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
description
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
data 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family typewriter
\shape slanted
\emph on
uuuuuu uuuuxxxx xxxxxxxx
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
a 12-bit data pointer in data RAM memory
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
code
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family typewriter
\shape slanted
\emph on
uxxxxx xxxxxxxx xxxxxxxx
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
a 21-bit code pointer in FLASH memory
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
eeprom
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family typewriter
\shape slanted
\emph on
uuuuuu uuuuuuxx xxxxxxxx
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
a 10-bit eeprom pointer in EEPROM memory
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
(unimplemented)
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family typewriter
\shape slanted
\emph on
xxxxxx xxxxxxxx xxxxxxxx
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
unimplemented pointer type
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
\noindent
Generic pointer are read and written with a set of library functions which read/write 1,
 2,
 3,
 4 bytes.
\end_layout

\begin_layout Subsection
Configuration Bits
\end_layout

\begin_layout Standard
Configuration bits (also known as fuses) can be configured using one of two methods:
\end_layout

\begin_layout Itemize
using #pragma config (see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:PIC16_Pragmas"
nolink "false"

\end_inset

),
 which is a preferred method for the new code.
 Example:
\end_layout

\begin_layout LyX-Code
#pragma config CP0=OFF,OSCS=ON,OSC=LP,BOR=ON,BORV=25,WDT=ON,WDTPS=128,CCP2MUX=ON
\end_layout

\begin_layout LyX-Code
#pragma config STVR=ON
\end_layout

\begin_layout Itemize
using `
\family typewriter
__code
\family default
' and `
\family typewriter
__at
\family default
' modifiers.
 This method is deprecated.
 Possible options should be ANDed and can be found in your processor header file.
 Example for PIC18F2550:
\end_layout

\begin_layout LyX-Code

\family typewriter
#include <pic18fregs.h> //Contains config addresses and options
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

static __code char __at(__CONFIG1L) configword1l =
\begin_inset Newline newline
\end_inset

  _USBPLL_CLOCK_SRC_FROM_96MHZ_PLL_2_1L &
\end_layout

\begin_layout LyX-Code

\family typewriter
  _PLLDIV_NO_DIVIDE__4MHZ_INPUT__1L & [...];
\begin_inset Newline newline
\end_inset

static __code char __at(__CONFIG1H) configword1h = [...];
\begin_inset Newline newline
\end_inset

static __code char __at(__CONFIG2L) configword2l = [...];
\begin_inset Newline newline
\end_inset

//More configuration words
\end_layout

\begin_layout Standard
Mixing both methods is not allowed and throws an error message 
\begin_inset Quotes sld
\end_inset

mixing __CONFIG and CONFIG directives
\begin_inset Quotes srd
\end_inset

.
\end_layout

\begin_layout Subsection
PIC16 C Libraries
\end_layout

\begin_layout Subsubsection
Standard I/O Streams
\end_layout

\begin_layout Standard
In the 
\emph on
stdio.h
\emph default
 the type FILE is defined as:
\end_layout

\begin_layout LyX-Code
typedef char * FILE;
\end_layout

\begin_layout Standard
This type is the stream type implemented I/O in the PIC18F devices.
 Also the standard input and output streams are declared in stdio.h:
\end_layout

\begin_layout LyX-Code
extern FILE * stdin;
\end_layout

\begin_layout LyX-Code
extern FILE * stdout;
\end_layout

\begin_layout Standard
The FILE type is actually a generic pointer which defines one more type of generic pointers,
 the 
\emph on
stream
\emph default
 pointer.
 This new type has the format:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\noindent
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="2" columns="7">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="left" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
pointer type
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
<7:6>
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
<5>
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
<4>
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
<3:0>
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
rest of the pointer
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
descrption
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
stream
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
00
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
nnnn
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family typewriter
\shape slanted
\emph on
uuuuuuuu uuuuuuuu
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
upper byte high nubble is 0x2n,
 the rest are zeroes
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
\noindent
Currently implemented there are 3 types of streams defined:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\noindent
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="4" columns="4">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
stream type
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
value
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
module
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
description
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
STREAM_USART
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family typewriter
0x200000UL
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
USART
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Writes/Reads characters via the USART peripheral
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
STREAM_MSSP
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family typewriter
0x210000UL
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
MSSP
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Writes/Reads characters via the MSSP peripheral
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
STREAM_USER
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family typewriter
0x2f0000UL
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
(none)
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Writes/Reads characters via used defined functions
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
\noindent
The stream identifiers are declared as macros in the stdio.h header.
\end_layout

\begin_layout Standard
\noindent
In the libc library there exist the functions that are used to write to each of the above streams.
 These are
\end_layout

\begin_layout Description
_
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

_stream_usart_putchar writes a character at the USART stream
\end_layout

\begin_layout Description
_
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

_stream_mssp_putchar writes a character at the MSSP stream
\end_layout

\begin_layout Description
putchar dummy function.
 This writes a character to a user specified manner.
\end_layout

\begin_layout Standard
In order to increase performance 
\emph on
putchar
\emph default
 is declared in stdio.h as having its parameter in WREG (it has the 
\emph on
__wparam
\emph default
 keyword).
 In stdio.h exists the macro PUTCHAR(arg) that defines the putchar function in a user-friendly way.
 
\emph on
arg
\emph default
 is the name of the variable that holds the character to print.
 An example follows:
\end_layout

\begin_layout LyX-Code
#include <pic18fregs.h>
\begin_inset Newline newline
\end_inset

#include <stdio.h>
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

PUTCHAR( c )
\end_layout

\begin_layout LyX-Code
{
\end_layout

\begin_layout LyX-Code
    PORTA = c;
    /* dump character c to PORTA */
\end_layout

\begin_layout LyX-Code
}
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void main(void)
\end_layout

\begin_layout LyX-Code
{
\end_layout

\begin_layout LyX-Code
    stdout = STREAM_USER;
    /* this is not necessary,
 since stdout points
\end_layout

\begin_layout LyX-Code
                              * by default to STREAM_USER */
\end_layout

\begin_layout LyX-Code
    printf (
\begin_inset Quotes sld
\end_inset

This is a printf test
\backslash
n
\begin_inset Quotes srd
\end_inset

);
\end_layout

\begin_layout LyX-Code
}
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout Subsubsection
Printing functions
\end_layout

\begin_layout Standard
PIC16 contains an implementation of the printf-family
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
printf()!PIC16
\end_layout

\end_inset

 of functions.
 There exist the following functions:
\end_layout

\begin_layout LyX-Code
extern unsigned int sprintf(char *buf,
 char *fmt,
 ...);
\end_layout

\begin_layout LyX-Code
extern unsigned int vsprintf(char *buf,
 char *fmt,
 va_list ap);
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout LyX-Code
extern unsigned int printf(char *fmt,
 ...);
\end_layout

\begin_layout LyX-Code
extern unsigned int vprintf(char *fmt,
 va_lista ap);
\end_layout

\begin_layout LyX-Code

\end_layout

\begin_layout LyX-Code
extern unsigned int fprintf(FILE *fp,
 char *fmt,
 ...);
\end_layout

\begin_layout LyX-Code
extern unsigned int vfprintf(FILE *fp,
 char *fmt,
 va_list ap);
\end_layout

\begin_layout Standard
For sprintf and vsprintf 
\emph on
buf
\emph default
 should normally be a data pointer where the resulting string will be placed.
 No range checking is done so the user should allocate the necessary buffer.
 For fprintf and vfprintf 
\emph on
fp
\emph default
 should be a stream pointer (i.e.
 stdout,
 STREAM_MSSP,
 etc...).
\end_layout

\begin_layout Subsubsection
Signals
\end_layout

\begin_layout Standard
The PIC18F family of microcontrollers supports a number of interrupt sources.
 A list of these interrupts is shown in the following table:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="11" columns="4">
<features tabularvalignment="middle">
<column alignment="left" valignment="top">
<column alignment="center" valignment="top">
<column alignment="left" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
signal name
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
description
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
signal name
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
description
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_RB
\end_layout

\end_inset
</cell>
<cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PORTB change interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_EE
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
EEPROM/FLASH write complete interrupt
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_INT0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
INT0 external interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_BCOL
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Bus collision interrupt
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_INT1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
INT1 external interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_LVD
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Low voltage detect interrupt
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_INT2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
INT2 external interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_PSP
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Parallel slave port interrupt
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_CCP1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
CCP1 module interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_AD
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
AD convertion complete interrupt
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_CCP2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
CCP2 module interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_RC
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
USART receive interrupt
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_TMR0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
TMR0 overflow interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_TX
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
USART transmit interrupt
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_TMR1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
TMR1 overflow interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_MSSP
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SSP receive/transmit interrupt
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_TMR2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
TMR2 matches PR2 interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SIG_TMR3
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
TMR3 overflow interrupt
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
\noindent
The prototypes for these names are defined in the header file 
\emph on
signal.h
\emph default
.
\end_layout

\begin_layout Standard
\noindent
In order to simplify signal handling,
 a number of macros is provided:
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
DEF_INTHIGH(name) begin the definition of the interrupt dispatch table for high priority interrupts.
 
\emph on
name
\emph default
 is the function name to use.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
DEF_INTLOW(name) begin the definition of the interrupt dispatch table for low priority interrupt.
 
\emph on
name
\emph default
 is the function name to use.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
DEF_HANDLER(sig,handler) define a handler for signal 
\emph on
sig.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
END_DEF end the declaration of the dispatch table.
\end_layout

\begin_layout Standard
Additionally there are two more macros to simplify the declaration of the signal handler:
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000

\series medium
SIGHANDLER(handler)
\series default
 this declares the function prototype for the 
\emph on
handler
\emph default
 function.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
SIGHANDLERNAKED(handler) same as SIGHANDLER() but declares a naked function.
\end_layout

\begin_layout Standard
An example of using the macros above is shown below:
\end_layout

\begin_layout LyX-Code
#include <pic18fregs.h>
\end_layout

\begin_layout LyX-Code
#include <signal.h>
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

DEF_INTHIGH(high_int)
\end_layout

\begin_layout LyX-Code
DEF_HANDLER(SIG_TMR0,
 _tmr0_handler)
\end_layout

\begin_layout LyX-Code
DEF_HANDLER(SIG_BCOL,
 _bcol_handler)
\end_layout

\begin_layout LyX-Code
END_DEF
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

SIGHANDLER(_tmr0_handler)
\end_layout

\begin_layout LyX-Code
{
\end_layout

\begin_layout LyX-Code
  /* action to be taken when timer 0 overflows */
\end_layout

\begin_layout LyX-Code
}
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

SIGHANDLERNAKED(_bcol_handler)
\end_layout

\begin_layout LyX-Code
{
\end_layout

\begin_layout LyX-Code
  __asm
\end_layout

\begin_layout LyX-Code
    /* action to be taken when bus collision occurs */
\end_layout

\begin_layout LyX-Code
    retfie
\end_layout

\begin_layout LyX-Code
 __endasm;
\end_layout

\begin_layout LyX-Code
}
\end_layout

\begin_layout Standard

\series bold
NOTES:

\series default
 Special care should be taken when using the above scheme:
\end_layout

\begin_layout Itemize
do not place a colon (;) at the end of the DEF_* and END_DEF macros.
\end_layout

\begin_layout Itemize
when declaring SIGHANDLERNAKED handler never forget to use 
\emph on
retfie
\emph default
 for proper returning.
\end_layout

\begin_layout Subsection
PIC16 Port – Tips
\end_layout

\begin_layout Standard
Here you can find some general tips for compiling programs with SDCC/pic16.
\end_layout

\begin_layout Subsubsection
Stack size
\end_layout

\begin_layout Standard
The default stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
PIC16!stack
\end_layout

\end_inset

 size (that is 64 bytes) probably is enough for many programs.
 One must take care that when there are many levels of function nesting,
 or there is excessive usage of stack,
 its size should be extended.
 An example of such a case is the printf/sprintf family of functions.
 If you encounter problems like not being able to print integers,
 then you need to set the stack size around the maximum (256 for small stack model).
 The following diagram shows what happens when calling printf to print an integer:
\end_layout

\begin_layout LyX-Code
printf () --> ltoa () --> ultoa () --> divschar ()
\end_layout

\begin_layout Standard
It is should be understood that stack is easily consumed when calling complicated functions.
 Using command line arguments like -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-fomit-frame-pointer might reduce stack usage by not creating unnecessary stack frames.
 Other ways to reduce stack usage may exist.
\end_layout

\begin_layout Subsection
Known Bugs
\end_layout

\begin_layout Subsubsection
Extended Instruction Set
\end_layout

\begin_layout Standard
The PIC16 port emits code which is incompatible with the extended instruction set available with many newer devices.
 Make sure to always explicitly disable it,
 usually using:
\end_layout

\begin_layout Itemize

\family typewriter
#pragma config XINST=OFF
\end_layout

\begin_layout Standard
or deprecated:
\end_layout

\begin_layout Itemize

\family typewriter
static __code char __at(__CONFIG4L) conf4l = /* more flags & */ _XINST_OFF_4L;
\end_layout

\begin_layout Standard
\noindent
Some devices (namely 18f2455,
 18f2550,
 18f4455,
 and 18f4550) use _ENHCPU_OFF_4L instead of _XINST_OFF_4L.
\end_layout

\begin_layout Subsubsection
Regression Tests
\end_layout

\begin_layout Standard
The PIC16 port currently passes most but not all of the tests in SDCC's regression test
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Regression test (PIC16)
\end_layout

\end_inset

 suite (see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Quality-control"
nolink "false"

\end_inset

),
 thus no automatic regression tests are currently performed for the PIC16 target.
\end_layout

\begin_layout Section
The MOS6502 port
\end_layout

\begin_layout Standard
The mos6502
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
MOS6502
\end_layout

\end_inset

 port can target the original MOS Technology NMOS 6502 ,
 and the CMOS Rockwell/WDC 65C02 with enhanched instruction set.
 
\end_layout

\begin_layout Subsection
Startup Code
\end_layout

\begin_layout Standard
On the MOS6502
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
MOS6502
\end_layout

\end_inset

 the startup code is inserted by linking with crt0.rel which is generated from sdcc/device/lib/mos6502/crt0.s.
 If you need a different startup code you can use the compiler option 
\emph on
-
\series bold
\emph default

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\series default
\emph on
-no-std-crt0
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-no-std-crt0
\end_layout

\end_inset

 and provide your own crt0.rel.
 When using a custom crt0.rel it needs to be listed first when linking.
\end_layout

\begin_layout Subsection
Hooking up interrupts
\end_layout

\begin_layout Standard
ISR can be written in C using SDCC.
 However,
 to hook interrupts is necessary to customize crt0.asm and have the interrupt vectors point to the C functions.
\end_layout

\begin_layout Subsection
Reentrancy
\end_layout

\begin_layout Standard
Due to the very limited stack space,
 the MOS6502 port by default generates non-reentrant code.
 Re-entrant functions should be declared using the __reentrant keyword.
 Alternatively the entire program can be compiled using –stack-auto.
 On the MOS6502 re-entrant code is,
 in general,
 much less efficient.
\end_layout

\begin_layout Subsection
Code and Data placement
\end_layout

\begin_layout Standard
The compiler can pass segment location to the linker.
 On the MOS6502 the following switches are supported:
\end_layout

\begin_layout Standard
–code-loc:
 start address of the code segment
\end_layout

\begin_layout Standard
–data-loc:
 start address of the zero page
\end_layout

\begin_layout Standard
–xram-loc:
 start address of the data segment
\end_layout

\begin_layout Chapter
Debugging
\end_layout

\begin_layout Standard
There are several approaches to debugging your code.
 This chapter is meant to show your options and to give detail on some of them:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

When writing your code:
\end_layout

\begin_layout Itemize
write your code with debugging in mind (avoid duplicating code,
 put conceptually similar variables into structs,
 use structured code,
 have strategic points within your code where all variables are consistent,
 ...)
\end_layout

\begin_layout Itemize
run a syntax-checking tool like splint
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
splint (syntax checking tool)
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
lint (syntax checking tool)
\end_layout

\end_inset

 (see -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-more-pedantic 
\begin_inset CommandInset ref
LatexCommand ref
reference "lyx:more-pedantic-SPLINT"
nolink "false"

\end_inset

) over the code.
\end_layout

\begin_layout Itemize
for the high level code use a C-compiler (like f.e.
 GCC) to compile run and debug the code on your host.
 See (see -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-more-pedantic 
\begin_inset CommandInset ref
LatexCommand ref
reference "lyx:more-pedantic-SPLINT"
nolink "false"

\end_inset

) on how to handle syntax extensions like __xdata,
 __at(),
 ...
 
\end_layout

\begin_layout Itemize
use another C-compiler to compile code for your target.
 Always an option but not recommended:) And not very likely to help you.
 If you seriously consider walking this path you should at least occasionally check portability of your code.
 Most commercial compiler vendors will offer an evaluation version so you can test compile your code or snippets of your code.
\end_layout

\begin_layout Standard
Debugging on a simulator:
\end_layout

\begin_layout Itemize
there is a separate section about SDCDB (section 
\begin_inset CommandInset ref
LatexCommand ref
reference "cha:Debugging-with-SDCDB"
nolink "false"

\end_inset

) below.
\end_layout

\begin_layout Itemize
or (8051 specific) use a free open source/commercial simulator which interfaces to the AOMF
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
AOMF,
 AOMF51
\end_layout

\end_inset

 file (see 
\begin_inset CommandInset ref
LatexCommand ref
reference "OMF file"
nolink "false"

\end_inset

) optionally generated by SDCC.
\end_layout

\begin_layout Standard
Debugging On-target:
 
\end_layout

\begin_layout Itemize
use a MCU port pin to serially output debug data to the RS232 port of your host.
 You'll probably want some level shifting device typically involving a MAX232 or similar IC.
 If the hardware serial port of the MCU is not available search for 'Software UART' in your favourite search machine.
\end_layout

\begin_layout Itemize
use an on-target monitor.
 In this context a monitor is a small program which usually accepts commands via a serial line and allows to set program counter,
 to single step through a program and read/write memory locations.
 For the 8051 good examples of monitors are paulmon and cmon51 (see section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Related-open-source-tools"
nolink "false"

\end_inset

).
\end_layout

\begin_layout Itemize
toggle MCU port pins at strategic points within your code and use an oscilloscope.
 A 
\emph on
digital oscilloscope
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Oscilloscope
\end_layout

\end_inset

 with deep trace memory is really helpful especially if you have to debug a realtime application.
 If you need to monitor more pins than your oscilloscope provides you can sometimes get away with a small R-2R network.
 On a single channel oscilloscope you could for example monitor 2 push-pull driven pins by connecting one via a 10
\begin_inset space ~
\end_inset

k
\begin_inset Formula $\Omega$
\end_inset

 resistor and the other one by a 5
\begin_inset space ~
\end_inset

k
\begin_inset Formula $\Omega$
\end_inset

 resistor to the oscilloscope probe (check output drive capability of the pins you want to monitor).
 If you need to monitor many more pins a 
\emph on
logic analyzer
\emph default
 will be handy.
\end_layout

\begin_layout Itemize
use an ICE (
\emph on
i
\emph default
n 
\emph on
c
\emph default
ircuit 
\emph on
e
\emph default
mulator
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
ICE (in circuit emulator)
\end_layout

\end_inset

).
 Usually very expensive.
 And very nice to have too.
 And usually locks you (for years...) to the devices the ICE can emulate.
 
\end_layout

\begin_layout Itemize
use a remote debugger.
 In most 8-bit systems the symbol information is not available on the target,
 and a complete debugger is too bulky for the target system.
 Therefore usually a debugger on the host system connects to an on-target debugging stub which accepts only primitive commands.
 
\begin_inset Newline newline
\end_inset

Terms to enter into your favourite search engine could be 'remote debugging',
 'gdb stub' or 'inferior debugger'.
 (is there one?)
\end_layout

\begin_layout Itemize
use an on target hardware debugger.
 Some of the more modern MCUs include hardware support for setting break points and monitoring/changing variables by using dedicated hardware pins.
 This facility doesn't require additional code to run on the target and 
\emph on
usually
\emph default
 doesn't affect runtime behaviour until a breakpoint is hit.
 For the mcs51 most hardware debuggers use the AOMF
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
AOMF,
 AOMF51
\end_layout

\end_inset

 file (see 
\begin_inset CommandInset ref
LatexCommand ref
reference "OMF file"
nolink "false"

\end_inset

) as input file.
 
\end_layout

\begin_layout Standard
Last not least:
\end_layout

\begin_layout Itemize
if you are not familiar with any of the following terms you're likely to run into problems rather sooner than later:
 
\emph on
volatile
\emph default
,
 
\emph on
atomic
\emph default
,
 
\emph on
memory map
\emph default
,
 
\emph on
overlay
\emph default
.
 As an embedded programmer you 
\emph on
have
\emph default
 to know them so why not look them up 
\emph on
before
\emph default
 you have problems?)
\end_layout

\begin_layout Itemize
tell someone else about your problem (actually this is a surprisingly effective means to hunt down the bug even if the listener is not familiar with your environment).
 As 'failure to communicate' is probably one of the job-induced deformations of an embedded programmer this is highly encouraged.
\end_layout

\begin_layout Section
Debugging with SDCDB
\begin_inset CommandInset label
LatexCommand label
name "cha:Debugging-with-SDCDB"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCDB (debugger)
\end_layout

\end_inset

 
\end_layout

\begin_layout Standard
SDCC is distributed with a source level debugger
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Debugger
\end_layout

\end_inset

.
 The debugger uses a command line interface,
 the command repertoire of the debugger has been kept as close to gdb
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
gdb
\end_layout

\end_inset

 (the GNU debugger) as possible.
 The configuration and build process is part of the standard compiler installation,
 which also builds and installs the debugger in the target directory specified during configuration.
 The debugger allows you debug BOTH at the C source and at the ASM source level.
\end_layout

\begin_layout Subsection
Compiling for Debugging
\end_layout

\begin_layout Standard
The -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug
\end_layout

\end_inset

 option must be specified for all files for which debug information is to be generated.
 The compiler generates a .adb file for each of these files.
 The linker creates the .cdb
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.cdb
\end_layout

\end_inset

 file from the .adb
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
<file>.adb
\end_layout

\end_inset

 files and the address information.
 This .cdb is used by the debugger.
\end_layout

\begin_layout Subsection
How the Debugger Works
\end_layout

\begin_layout Standard
When the -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-debug option is specified the compiler generates extra symbol information some of which are put into the assembler source and some are put into the .adb file.
 Then the linker creates the .cdb file from the individual .adb files with the address information for the symbols.
 The debugger reads the symbolic information generated by the compiler & the address information generated by the linker.
 It uses the SIMULATOR (Daniel's S51) to execute the program,
 the program execution is controlled by the debugger.
 When a command is issued for the debugger,
 it translates it into appropriate commands for the simulator.
 (Currently SDCDM only connects to the simulator but 
\emph on
newcdb
\emph default
 at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://ec2drv.sourceforge.net/
\end_layout

\end_inset

 is an effort to connect directly to the hardware.) 
\end_layout

\begin_layout Subsection
Starting the Debugger SDCDB
\end_layout

\begin_layout Standard
The debugger can be started using the following command line.
 (Assume the file you are debugging has the file name foo).
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
sdcdb foo
\begin_inset Newline newline
\end_inset


\family default
\series default

\begin_inset Newline newline
\end_inset

The debugger will look for the following files.
\end_layout

\begin_layout Itemize
foo.c - the source file.
\end_layout

\begin_layout Itemize
foo.cdb - the debugger symbol information file.
\end_layout

\begin_layout Itemize
foo.ihx - the Intel hex format
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Intel hex format
\end_layout

\end_inset

 object file.
\end_layout

\begin_layout Subsection
SDCDB Command Line Options
\end_layout

\begin_layout Itemize
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-directory=<source file directory> this option can used to specify the directory search list.
 The debugger will look into the directory list specified for source,
 cdb & ihx files.
 The items in the directory list must be separated by ':',
 e.g.
 if the source files can be in the directories /home/src1 and /home/src2,
 the -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-directory option should be -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-directory=/home/src1:/home/src2.
 Note there can be no spaces in the option.
 
\end_layout

\begin_layout Itemize
-cd <directory> - change to the <directory>.
\end_layout

\begin_layout Itemize
-fullname - used by GUI front ends.
\end_layout

\begin_layout Itemize
-cpu <cpu-type> - this argument is passed to the simulator please see the simulator docs for details.
\end_layout

\begin_layout Itemize
-X <Clock frequency > this options is passed to the simulator please see the simulator docs for details.
\end_layout

\begin_layout Itemize
-s <serial port file> passed to simulator see the simulator docs for details.
\end_layout

\begin_layout Itemize
-S <serial in,out> passed to simulator see the simulator docs for details.
\end_layout

\begin_layout Itemize
-k <port number> passed to simulator see the simulator docs for details.
\end_layout

\begin_layout Subsection
SDCDB Debugger Commands
\end_layout

\begin_layout Standard
As mentioned earlier the command interface for the debugger has been deliberately kept as close the GNU debugger gdb,
 as possible.
 This will help the integration with existing graphical user interfaces (like ddd,
 xxgdb or xemacs) existing for the GNU debugger.
 If you use a graphical user interface for the debugger you can skip this section.
\end_layout

\begin_layout Subsubsection*
break [line | file:line | function | file:function]
\end_layout

\begin_layout Standard
Set breakpoint at specified line or function:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
sdcdb>break 100 
\begin_inset Newline newline
\end_inset

sdcdb>break foo.c:100
\begin_inset Newline newline
\end_inset

sdcdb>break funcfoo
\begin_inset Newline newline
\end_inset

sdcdb>break foo.c:funcfoo
\end_layout

\begin_layout Subsubsection*
clear [line | file:line | function | file:function ]
\end_layout

\begin_layout Standard
Clear breakpoint at specified line or function:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
sdcdb>clear 100
\begin_inset Newline newline
\end_inset

sdcdb>clear foo.c:100
\begin_inset Newline newline
\end_inset

sdcdb>clear funcfoo
\begin_inset Newline newline
\end_inset

sdcdb>clear foo.c:funcfoo
\end_layout

\begin_layout Subsubsection*
continue
\end_layout

\begin_layout Standard
Continue program being debugged,
 after breakpoint.
\end_layout

\begin_layout Subsubsection*
finish
\end_layout

\begin_layout Standard
Execute till the end of the current function.
\end_layout

\begin_layout Subsubsection*
delete [n]
\end_layout

\begin_layout Standard
Delete breakpoint number 'n'.
 If used without any option clear ALL user defined break points.
\end_layout

\begin_layout Subsubsection*
info [break | stack | frame | registers ]
\end_layout

\begin_layout Itemize
info break - list all breakpoints
\end_layout

\begin_layout Itemize
info stack - show the function call stack.
\end_layout

\begin_layout Itemize
info frame - show information about the current execution frame.
\end_layout

\begin_layout Itemize
info registers - show content of all registers.
\end_layout

\begin_layout Subsubsection*
step
\end_layout

\begin_layout Standard
Step program until it reaches a different source line.
 Note:
 pressing <return> repeats the last command.
\end_layout

\begin_layout Subsubsection*
next
\end_layout

\begin_layout Standard
Step program,
 proceeding through subroutine calls.
\end_layout

\begin_layout Subsubsection*
run
\end_layout

\begin_layout Standard
Start debugged program.
\end_layout

\begin_layout Subsubsection*
ptype variable 
\end_layout

\begin_layout Standard
Print type information of the variable.
\end_layout

\begin_layout Subsubsection*
print variable
\end_layout

\begin_layout Standard
print value of variable.
\end_layout

\begin_layout Subsubsection*
file filename
\end_layout

\begin_layout Standard
load the given file name.
 Note this is an alternate method of loading file for debugging.
\end_layout

\begin_layout Subsubsection*
frame
\end_layout

\begin_layout Standard
print information about current frame.
\end_layout

\begin_layout Subsubsection*
set srcmode
\end_layout

\begin_layout Standard
Toggle between C source & assembly source.
\end_layout

\begin_layout Subsubsection*
!
 simulator command
\end_layout

\begin_layout Standard
Send the string following '!' to the simulator,
 the simulator response is displayed.
 Note the debugger does not interpret the command being sent to the simulator,
 so if a command like 'go' is sent the debugger can loose its execution context and may display incorrect values.
\end_layout

\begin_layout Subsubsection*
quit
\end_layout

\begin_layout Standard
"Watch me now.
 Iam going Down.
 My name is Bobby Brown"
\end_layout

\begin_layout Subsection
Interfacing SDCDB with DDD
\end_layout

\begin_layout Standard
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
The screenshot was converted from png to eps with:
 
\begin_inset Quotes sld
\end_inset

bmeps -c -e8f -p3 ddd_example.png >ddd_example.eps
\begin_inset Quotes srd
\end_inset

 which produces a pretty compact eps file which is free from compression artifacts.
\end_layout

\begin_layout Plain Layout
The screenshot was included in sdccman.lyx cvs version 1.120 but later removed as this broke the build system on Sourceforge (pdf-file was broken.
 pdflatex does not accept eps files).
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The 
\emph on
p
\emph default
ortable 
\emph on
n
\emph default
etwork 
\emph on
g
\emph default
raphics File 
\size footnotesize

\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/wiki_images/ddd_example.png
\end_layout

\end_inset


\size default
 shows a screenshot of a debugging session with DDD
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DDD (debugger)
\end_layout

\end_inset

 (Unix only) on a simulated 8032.
 The debugging session might not run as smoothly as the screenshot suggests.
 The debugger allows setting of breakpoints,
 displaying and changing variables,
 single stepping through C and assembler code.
 
\begin_inset Newline newline
\end_inset

The source was compiled with 
\family sans
\series bold

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

sdcc -
\family default
\series default

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\family sans
\series bold
-debug ddd_example.c
\family default
\series default
 
\family sans
\series bold

\begin_inset Newline newline
\end_inset


\family default
\series default

\begin_inset Newline newline
\end_inset

and DDD was invoked with 
\family sans
\series bold

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

ddd -debugger "sdcdb -cpu 8032 ddd_example"
\end_layout

\begin_layout Standard
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
Check that the double quotes or an apostrophe within the command line survive the \SpecialChar LyX
 tool chain.
 Previously the apostrophes got slanted in the PDF output so a cut and paste did not work.
\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Interfacing SDCDB with XEmacs
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
XEmacs
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Emacs
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Two files (in emacs lisp) are provided for the interfacing with XEmacs,
 sdcdb.el and sdcdbsrc.el.
 These two files can be found in the $(prefix)/bin directory after the installation is complete.
 These files need to be loaded into XEmacs for the interface to work.
 This can be done at XEmacs startup time by inserting the following into your '.xemacs' file (which can be found in your HOME directory):
 
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family typewriter
(load-file sdcdbsrc.el)
\family default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

.xemacs is a lisp file so the () around the command is REQUIRED.
 The files can also be loaded dynamically while XEmacs is running,
 set the environment variable 'EMACSLOADPATH' to the installation bin directory (<installdir>/bin),
 then enter the following command ESC-x load-file sdcdbsrc.
 To start the interface enter the following command:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family sans
\series bold
ESC-x sdcdbsrc
\family default
\series default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

You will prompted to enter the file name to be debugged.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The command line options that are passed to the simulator directly are bound to default values in the file sdcdbsrc.el.
 The variables are listed below,
 these values maybe changed as required.
\end_layout

\begin_layout Itemize
sdcdbsrc-cpu-type '51
\end_layout

\begin_layout Itemize
sdcdbsrc-frequency '11059200
\end_layout

\begin_layout Itemize
sdcdbsrc-serial nil
\end_layout

\begin_layout Standard
The following is a list of key mapping for the debugger interface.
\end_layout

\begin_layout Standard
\begin_inset space ~
\end_inset


\family typewriter

\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset

Current Listing ::
\begin_inset Newline newline
\end_inset

;;key
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

binding
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

Comment
\begin_inset Newline newline
\end_inset

;;---
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

-------
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

-------
\begin_inset Newline newline
\end_inset

;;
 
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset

n
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcdb-next-from-src
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

SDCDB next command
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset

b
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcdb-back-from-src
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

SDCDB back command
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset

c
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcdb-cont-from-src
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

SDCDB continue command
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset

s
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcdb-step-from-src
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

SDCDB step command
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset

?
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcdb-whatis-c-sexp
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

SDCDB ptypecommand for data at
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

buffer point
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset

x
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcdbsrc-delete
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

SDCDB Delete all breakpoints if no arg
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

given or delete arg (C-u arg x)
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset

m
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcdbsrc-frame
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

SDCDB Display current frame if no arg,
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

given or display frame arg
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

buffer point
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset

!
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcdbsrc-goto-sdcdb
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

Goto the SDCDB output buffer
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset

p
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sdcdb-print-c-sexp
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

SDCDB print command for data at
\begin_inset Newline newline
\end_inset

;;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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;;
\end_layout

\begin_layout Section
Debugging with other debuggers (e.g.
 GDB):
 ELF / DWARF
\end_layout

\begin_layout Standard
For some ports,
 SDCC can create ELF binaries with DWARF debug information.
 This can e.g.
 be used for on-target debugging on STM8 using OpenOCD and GDB.
 To do so,
 compile with –debug –out-fmt-elf.
 Note that –out-fmt-elf needs to be specified both when compiling (to generate the debug info in DWARF rather than CDB format) and linking (to get an ELF binary instead of Intel Hex).
\end_layout

\begin_layout Chapter
TIPS
\end_layout

\begin_layout Standard
Here are a few guidelines that will help the compiler generate more efficient code,
 some of the tips are specific to this compiler others are generally good programming practice.
\end_layout

\begin_layout Itemize
Use the smallest data type to represent your data-value.
 If it is known in advance that the value is going to be less than 256 then use an 'unsigned char' instead of a 'short' or 'int'.
 Please note,
 that ANSI C requires both signed and unsigned chars to be promoted to 'signed int'
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
promotion to signed int
\end_layout

\end_inset


\begin_inset Marginal
status collapsed

\begin_layout Plain Layout

\series bold
\begin_inset space ~
\end_inset

!
\end_layout

\end_inset

 before doing any operation.
 This promotion
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
type promotion
\end_layout

\end_inset


\begin_inset CommandInset label
LatexCommand label
name "type promotion"

\end_inset

 can be omitted,
 if the result is the same.
 The effect of the promotion rules together with the sign-extension is often surprising:
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_deeper
\begin_layout Verse

\family typewriter
unsigned char uc = 0xfe;
\begin_inset Newline newline
\end_inset

if (uc * uc < 0) /* this is true!
 */
\begin_inset Newline newline
\end_inset

{
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\end_inset


\begin_inset space ~
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\begin_inset space ~
\end_inset

....
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard

\family typewriter
uc * uc
\family default
 is evaluated as 
\family typewriter
(int) uc * (int) uc = (int) 0xfe * (int) 0xfe = (int) 0xfc04 = -1024
\family default
.
\begin_inset Newline newline
\end_inset

Another one:
\end_layout

\begin_layout Verse

\family typewriter
(unsigned char) -12 / (signed char) -3 = ...
\end_layout

\begin_layout Standard
No,
 the result is not 4:
\end_layout

\begin_layout Verse

\family typewriter
(int) (unsigned char) -12 / (int) (signed char) -3 =
\begin_inset Newline newline
\end_inset

(int) (unsigned char) 0xf4 / (int) (signed char) 0xfd =
\begin_inset Newline newline
\end_inset

(int) 0x00f4 / (int) 0xfffd =
\begin_inset Newline newline
\end_inset

(int) 0x00f4 / (int) 0xfffd =
\begin_inset Newline newline
\end_inset

(int) 244 / (int) -3 =
\begin_inset Newline newline
\end_inset

(int) -81 = (int) 0xffaf;
\end_layout

\begin_layout Standard
Don't complain,
 that gcc gives you a different result.
 gcc uses 32 bit ints,
 while SDCC uses 16 bit ints.
 Therefore the results are different.
\begin_inset Newline newline
\end_inset

From 
\begin_inset Quotes sld
\end_inset

comp.lang.c FAQ
\begin_inset Quotes srd
\end_inset

:
\end_layout

\begin_layout Quote

\emph on
If well-defined overflow characteristics are important and negative values are not,
 or if you want to steer clear of sign-extension problems when manipulating bits or bytes,
 use one of the corresponding unsigned types.
 (Beware when mixing signed and unsigned values in expressions,
 though.)
\begin_inset Newline newline
\end_inset

Although character types (especially unsigned char) can be used as "tiny" integers,
 doing so is sometimes more trouble than it's worth,
 due to unpredictable sign extension and increased code size.
\end_layout

\end_deeper
\begin_layout Itemize
Use unsigned when it is known in advance that the value is not going to be negative.
 This helps especially if you are doing division or multiplication,
 bit-shifting or are using an array index.
\end_layout

\begin_layout Itemize
NEVER jump into a LOOP.
\end_layout

\begin_layout Itemize
Declare the variables to be local
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
local variables
\end_layout

\end_inset

 whenever possible,
 especially loop control variables (induction).
\end_layout

\begin_layout Itemize
Have a look at the assembly listing to get a 
\begin_inset Quotes sld
\end_inset

feeling
\begin_inset Quotes srd
\end_inset

 for the code generation.
\end_layout

\begin_layout Section
Porting code from or to other compilers
\begin_inset CommandInset label
LatexCommand label
name "sec:Porting-code-to-other-compilers"

\end_inset


\end_layout

\begin_layout Itemize
check whether endianness
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Endianness
\end_layout

\end_inset

 of the compilers differs and adapt where needed.
\end_layout

\begin_layout Itemize
check the device specific header files
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Header files
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Include files
\end_layout

\end_inset

 for compiler specific syntax.
 Eventually include the file <compiler.h
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
compiler.h (include file)
\end_layout

\end_inset

> 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://svn.code.sf.net/p/sdcc/code/trunk/sdcc/device/include/mcs51/compiler.h
\end_layout

\end_inset

 to allow using common header files.
 (see f.e.
 cc2510fx.h 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://svn.code.sf.net/p/sdcc/code/trunk/sdcc/device/include/mcs51/cc2510fx.h
\end_layout

\end_inset

).
\end_layout

\begin_layout Itemize
check whether the startup code contains the correct initialization (watchdog
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
watchdog
\end_layout

\end_inset

,
 peripherals).
\end_layout

\begin_layout Itemize
check whether the sizes of short,
 int,
 long match.
\end_layout

\begin_layout Itemize
check if some 16 or 32 bit hardware registers require a specific addressing order (least significant or most significant byte first) and adapt if needed (
\emph on
first
\emph default
 and 
\emph on
last
\emph default
 relate to time and not to lower/upper memory location here,
 so this is 
\emph on
not
\emph default
 the same as endianness).
\end_layout

\begin_layout Itemize
check whether the keyword 
\emph on
volatile
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
volatile
\end_layout

\end_inset


\emph default
 is used where needed.
 The compilers might differ in their optimization characteristics (as different versions of the same compiler might also use more clever optimizations this is good idea anyway).
 See section 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Common-interrupt-pitfall-volatile"
nolink "false"

\end_inset

.
\end_layout

\begin_layout Itemize
check that the compilers are not told to suppress warnings.
\end_layout

\begin_layout Itemize
check and convert compiler specific extensions (interrupts,
 memory areas,
 pragmas etc.).
\end_layout

\begin_layout Itemize
check for differences in type promotion.
 Especially check for math operations on 
\family typewriter
char
\family default
 or 
\family typewriter
unsigned char
\family default
 variables.
 For the sake of C99 compatibility SDCC will probably promote these to 
\family typewriter
int
\family default
 more often than other compilers.
 Eventually insert explicit casts to 
\family typewriter
(char)
\family default
 or 
\family typewriter
(unsigned char)
\family default
.
 Also check that the ~
\begin_inset space ~
\end_inset

operator
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
~ Operator
\end_layout

\end_inset

 is not used on 
\family typewriter
bit
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
bit
\end_layout

\end_inset


\family default
 variables,
 use the !
\begin_inset space ~
\end_inset

operator instead.
 See sections 
\begin_inset CommandInset ref
LatexCommand ref
reference "type promotion"
nolink "false"

\end_inset

 and 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Compatibility-with-previous"
nolink "false"

\end_inset

.
\end_layout

\begin_layout Itemize
check the assembly code generated for interrupt routines (f.e.
 for calls to possibly non-reentrant library functions).
\end_layout

\begin_layout Itemize
check whether timing loops result in proper timing (or preferably consider a rewrite of the code with timer based delays instead).
\end_layout

\begin_layout Itemize
check for differences in printf parameters
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
printf()!parameters
\end_layout

\end_inset

 (some compilers push (va_arg
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
vararg,
 va
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
_
\end_layout

\end_inset

arg
\end_layout

\end_inset

) char variables as 
\family typewriter
int
\family default
 others push them as 
\family typewriter
char
\family default
.
 See section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Compatibility-with-previous"
nolink "false"

\end_inset

).
 Provide a putchar()
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
printf()!putchar()
\end_layout

\end_inset

 function if needed.
\end_layout

\begin_layout Itemize
check the resulting memory map
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Memory map
\end_layout

\end_inset

.
 Usage of different memory spaces:
 code,
 stack,
 data (for mcs51/ds390 additionally idata,
 pdata,
 xdata).
 Eventually check if unexpected library functions are included.
\end_layout

\begin_layout Section
Tools
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Tools
\end_layout

\end_inset

 included in the distribution
\end_layout

\begin_layout Standard
\align left
\begin_inset Tabular
<lyxtabular version="3" rows="29" columns="3">
<features tabularvalignment="middle">
<column alignment="left" valignment="top" width="0pt">
<column alignment="left" valignment="top" width="0pt">
<column alignment="left" valignment="top" width="0pt">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
Name
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
Purpose
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
Directory
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
as2gbmap.py
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
sdas map to rrgb map and no$gmb sym file format converter
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
sdcc/support/scripts
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
cinc2h.pl
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
gpasm inc to c header file converter
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
sdcc/support/scripts
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
gen_known_bugs.pl
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
generate knownbugs.html
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
sdcc/support/scripts
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
keil2sdcc.pl
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Keil header 
\begin_inset Index idx
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\begin_layout Plain Layout
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\end_layout

\end_inset


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range none
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\end_layout

\end_inset

 to SDCC header file converter
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
sdcc/support/scripts
\end_layout

\end_inset
</cell>
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<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
makebin
\end_layout

\end_inset
</cell>
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\begin_inset Text

\begin_layout Plain Layout
Intel Hex to binary and GameBoy binay format converter
\end_layout

\end_inset
</cell>
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\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
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\begin_inset Text

\begin_layout Plain Layout
ddd
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status collapsed

\begin_layout Plain Layout
DDD (debugger)
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Debugger,
 serves nicely as GUI to SDCDB
\begin_inset Index idx
range none
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status collapsed

\begin_layout Plain Layout
SDCDB (debugger)
\end_layout

\end_inset

 (Unix only)
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.gnu.org/software/ddd/
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" usebox="none">
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d52
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\begin_layout Plain Layout
d52
\end_layout

\end_inset


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d52 (disassembler)
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Disassembler,
 can count instruction cycles
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status collapsed

\begin_layout Plain Layout
instruction cycles (count)
\end_layout

\end_inset

,
 use with options -pnd
\end_layout

\end_inset
</cell>
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\begin_inset Text

\begin_layout Plain Layout
\begin_inset Flex URL
status collapsed

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http://www.8052.com/users/disasm/
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
cmake
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\begin_layout Plain Layout
cmake
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Cross platform build system,
 generates Makefiles
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range none
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\begin_layout Plain Layout
Makefile
\end_layout

\end_inset

 and project workspaces
\begin_inset Index idx
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\begin_layout Plain Layout
project workspace
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.cmake.org
\end_layout

\end_inset

 and a dedicated wiki entry:
 
\begin_inset Flex URL
status collapsed

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http://www.cmake.org/Wiki/CmakeSdcc
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Section
Related documentation / recommended reading
\end_layout

\begin_layout Standard
\align left
\begin_inset Tabular
<lyxtabular version="3" rows="7" columns="3">
<features tabularvalignment="middle">
<column alignment="left" valignment="top" width="20col%">
<column alignment="left" valignment="top" width="30col%">
<column alignment="left" valignment="top" width="50col%">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

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\series bold
Name
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

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\series bold
Subject / Title
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
Where to get
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\noun off
\color none
c-refcard.pdf
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
C Reference Card
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\begin_layout Plain Layout
C Reference card
\end_layout

\end_inset

,
 2 pages
\end_layout

\end_inset
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http://refcards.com/refcards/c/index.html
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</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
c-faq
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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\begin_layout Plain Layout
C-FAQ
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C FAQ
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http://www.c-faq.com
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\end_inset
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</row>
<row>
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\begin_inset Text

\begin_layout Plain Layout
ISO/IEC 9899:TC2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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\begin_layout Plain Layout
\begin_inset Quotes sld
\end_inset

C-Standard
\begin_inset Quotes srd
\end_inset


\end_layout

\end_inset
</cell>
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\size footnotesize
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http://www.open-std.org/jtc1/sc22/wg14/www/standards.html#9899
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\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
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\begin_inset Text

\begin_layout Plain Layout
ISO/IEC DTR 18037
\end_layout

\end_inset
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<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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\begin_layout Plain Layout
\begin_inset Quotes sld
\end_inset

Extensions for Embedded C
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\end_layout

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http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1021.pdf
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\end_layout

\end_inset
</cell>
</row>
<row>
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\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Latest datasheet of target CPU
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
vendor
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Revision history of datasheet
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
vendor
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Section
Application notes specifically for SDCC
\end_layout

\begin_layout Standard
SDCC makes no claims about the completeness of this list and about up-to-dateness or correctness of the application notes
\begin_inset Index idx
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\begin_layout Plain Layout
Application notes
\end_layout

\end_inset

.
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_layout Standard
\align left

\size footnotesize
\begin_inset Tabular
<lyxtabular version="3" rows="7" columns="3">
<features tabularvalignment="middle">
<column alignment="block" valignment="top" width="17col%">
<column alignment="block" valignment="top" width="27col%">
<column alignment="block" valignment="top" width="56col%">
<row>
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\begin_inset Text

\begin_layout Plain Layout

\series bold
\size footnotesize
Vendor
\end_layout

\end_inset
</cell>
<cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\series bold
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Subject / Title
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

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\series bold
\size footnotesize
Where to get
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Maxim / Dallas
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Using the SDCC Compiler for the DS80C400
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DS80C400
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
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\begin_inset Text

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http://pdfserv.maxim-ic.com/en/an/AN3346.pdf
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\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
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\size footnotesize
Maxim / Dallas
\end_layout

\end_inset
</cell>
<cell multicolumn="1" alignment="left" valignment="top" topline="true" leftline="true" usebox="none" width="30line%">
\begin_inset Text

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\size footnotesize
Using the Free SDCC C Compiler to Develop Firmware for the DS89C420/430/440/450
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DS89C4x0
\end_layout

\end_inset

 Family of Microcontrollers
\end_layout

\end_inset
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\end_layout

\end_inset
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Silicon Laboratories / Cygnal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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Integrating SDCC 8051 Tools Into The Silicon Labs IDE
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IDE
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
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http://www.silabs.com/public/documents/tpub_doc/anote/Microcontrollers/en/an198.pdf
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\end_layout

\end_inset
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Ramtron / Goal Semiconductor
\end_layout

\end_inset
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Interfacing SDCC to Syn and Textpad
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Ramtron / Goal Semiconductor
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Installing and Configuring SDCC and Crimson Editor 
\end_layout

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Texas Instruments
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MSC12xx Programming with SDCC
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http://focus.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=sbaa109&fileType=pdf
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\end_inset


\end_layout

\end_inset
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</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Section
Some Questions
\end_layout

\begin_layout Standard
Some questions answered,
 some pointers given - it might be time to in turn ask 
\emph on
you
\emph default
 some questions:
 
\end_layout

\begin_layout Itemize
can you solve your project with the selected microcontroller?
 Would you find out early or rather late that your target is too small/slow/whatever?
 Can you switch to a slightly better device if it doesn't fit?
\end_layout

\begin_layout Itemize
should you solve the problem with an 8 bit CPU?
 Or would a 16/32 bit CPU and/or another programming language be more adequate?
 Would an operating system on the target device help?
\end_layout

\begin_layout Itemize
if you solved the problem,
 will the marketing department be happy?
\end_layout

\begin_layout Itemize
if the marketing department is happy,
 will customers be happy?
\end_layout

\begin_layout Itemize
if you're the project manager,
 marketing department and maybe even the customer in one person,
 have you tried to see the project from the outside?
\end_layout

\begin_layout Itemize
is the project done if you think it is done?
 Or is just that other interface/protocol/feature/configuration/option missing?
 How about website,
 manual(s),
 internationali(z|s)ation,
 packaging,
 labels,
 2nd source for components,
 electromagnetic compatability/interference,
 documentation for production,
 production test software,
 update mechanism,
 patent issues?
\end_layout

\begin_layout Itemize
is your project adequately positioned in that magic triangle:
 fame,
 fortune,
 fun?
\end_layout

\begin_layout Standard
Maybe not all answers to these questions are known and some answers may even be 
\emph on
no
\emph default
,
 nevertheless knowing these questions may help you to avoid burnout
\begin_inset Foot
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burnout is bad for electronic devices,
 programmers and motorcycle tyres
\end_layout

\end_inset

.
 Chances are you didn't want to hear some of them...
\end_layout

\begin_layout Chapter
Support
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Support
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC has grown to be a large project.
 The compiler alone (without the preprocessor,
 assembler and linker) is well over 150,000 lines of code (blank stripped).
 The open source nature of this project is a key to its continued growth and support.
 You gain the benefit and support of many active software developers and end users.
 Is SDCC perfect?
 No,
 that's why we need your help.
 The developers take pride in fixing reported bugs.
 You can help by reporting the bugs and helping other SDCC users.
 There are lots of ways to contribute,
 and we encourage you to take part in making SDCC a great software package.
 
\end_layout

\begin_layout Standard
The SDCC project is hosted on the SDCC SourceForge site at 
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http://sourceforge.net/projects/sdcc
\end_layout

\end_inset

.
 You'll find the complete set of mailing lists
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Mailing list(s)
\end_layout

\end_inset

,
 forums,
 bug reporting system,
 patch submission
\begin_inset Index idx
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status open

\begin_layout Plain Layout
Patch submission
\end_layout

\end_inset

 system,
 wiki,
 rss-feed,
 download
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download
\end_layout

\end_inset

 area and Subversion code repository
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Subversion code repository
\end_layout

\end_inset

 there.
\end_layout

\begin_layout Section
Reporting Bugs
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\begin_layout Plain Layout
Bug reporting
\end_layout

\end_inset


\begin_inset Index idx
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Reporting bugs
\end_layout

\end_inset


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\begin_layout Plain Layout
Communication!Bug report
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The recommended way of reporting bugs is using the infrastructure of the SourceForge site.
 You can follow the status of bug reports there and have an overview about the known bugs.
\end_layout

\begin_layout Standard
Bug reports are automatically forwarded to the developer mailing list and will be fixed ASAP.
 When reporting a bug,
 it is very useful to include a small test program (the smaller the better) which reproduces the problem.
 If you can isolate the problem by looking at the generated assembly code,
 this can be very helpful.
 Compiling your program with the -
\begin_inset ERT
status collapsed

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\backslash
/
\end_layout

\end_inset

-dumpall
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-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-dumpall
\end_layout

\end_inset

 option can sometimes be useful in locating optimization problems.
 When reporting a bug please make sure you:
\end_layout

\begin_layout Enumerate
Attach the code you are compiling with SDCC.
 
\end_layout

\begin_layout Enumerate
Specify the exact command you use to run SDCC,
 or attach your Makefile.
 
\end_layout

\begin_layout Enumerate
Specify the SDCC version (type "
\family sans
\series bold
sdcc -v
\family default
\series default
"),
 your platform,
 and operating system.
 
\end_layout

\begin_layout Enumerate
Provide an exact copy of any error message or incorrect output.
 
\end_layout

\begin_layout Enumerate
Put something meaningful in the subject of your message.
\end_layout

\begin_layout Standard
Please attempt to include these 5 important parts,
 as applicable,
 in all requests for support or when reporting any problems or bugs with SDCC.
 Though this will make your message lengthy,
 it will greatly improve your chance that SDCC users and developers will be able to help you.
 Some SDCC developers are frustrated by bug reports without code provided that they can use to reproduce and ultimately fix the problem,
 so please be sure to provide sample code if you are reporting a bug!
 
\end_layout

\begin_layout Standard
Please have a short check that you are using a recent version of SDCC and the bug is not yet known.
 This is the link for reporting bugs:
 
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\begin_layout Plain Layout

http://sourceforge.net/p/sdcc/bugs/
\end_layout

\end_inset

.
 With SDCC on average having more than 200 downloads
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\begin_layout Plain Layout
download
\end_layout

\end_inset

 on SourceForge per day
\begin_inset Foot
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\begin_layout Plain Layout
220 daily downloads on average Jan-Sept 2006 and about 150 daily downloads between 2002 and 2005.
 This does not include other methods of distribution.
\end_layout

\end_inset

 there must be some users.
 So it's not exactly easy to find a new bug.
 If you find one we need it:
 
\emph on
reporting bugs is good
\emph default
.
\end_layout

\begin_layout Section
Requesting Features
\begin_inset CommandInset label
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name "subsec:Requesting-Features"

\end_inset


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Feature request
\end_layout

\end_inset


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Requesting features
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Communication!Feature request
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Like bug reports feature requests are forwarded to the developer mailing list.
 This is the link for requesting features:
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/p/sdcc/feature-requests/
\end_layout

\end_inset

.
\end_layout

\begin_layout Section
Submitting patches
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Communication!Patch submission
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Like bug reports contributed patches are forwarded to the developer mailing list.
 This is the link for submitting patches
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Patch submission
\end_layout

\end_inset

:
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/p/sdcc/patches/
\end_layout

\end_inset

.
\end_layout

\begin_layout Standard
You need to specify some parameters to the 
\family typewriter
diff
\family default
 command for the patches to be useful.
 If you modified more than one file a patch created f.e.
 with 
\family sans
\series bold

\begin_inset Quotes sld
\end_inset

diff -Naur unmodified_directory modified_directory >my_changes.patch
\begin_inset Quotes srd
\end_inset


\family default
\series default
 will be fine,
 otherwise 
\family sans
\series bold

\begin_inset Quotes sld
\end_inset

diff -u sourcefile.c.orig sourcefile.c >my_changes.patch
\begin_inset Quotes srd
\end_inset


\family default
\series default
 will do.
\end_layout

\begin_layout Section
Getting Help
\end_layout

\begin_layout Standard
These links should take you directly to the Mailing lists 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/p/sdcc/mailman/sdcc-user/
\end_layout

\end_inset


\begin_inset Foot
status collapsed

\begin_layout Plain Layout
Traffic on sdcc-devel and sdcc-user is about 100 mails/month each not counting automated messages (mid 2003)
\end_layout

\end_inset

 and the Forums 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/p/sdcc/discussion/
\end_layout

\end_inset

,
 lists
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Mailing list(s)
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Communication!Mailing lists
\end_layout

\end_inset

 and forums are archived and searchable so if you are lucky someone already had a similar problem.
 While mails to the lists themselves are delivered promptly their web front end on SourceForge sometimes shows a severe time lag (up to several weeks),
 if you're seriously using SDCC please consider subscribing to the lists.
\end_layout

\begin_layout Section
ChangeLog
\end_layout

\begin_layout Standard
You can follow the status of the Subversion version
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
version
\end_layout

\end_inset

 of SDCC by watching the Changelog
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Changelog
\end_layout

\end_inset

 in the Subversion repository
\size footnotesize
 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://svn.code.sf.net/p/sdcc/code/trunk/sdcc/ChangeLog
\end_layout

\end_inset

.
\end_layout

\begin_layout Section
Subversion Source Code Repository
\end_layout

\begin_layout Standard
The output of 
\family sans
\series bold
sdcc -
\family default

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\family sans
-version
\family default
\series default
 or the filenames of the snapshot versions of SDCC include date and its Subversion
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Subversion code repository
\end_layout

\end_inset

 number.
 Subversion allows to download the source of recent or previous versions 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/p/sdcc/code/8805/tree/
\end_layout

\end_inset

 (by number or by date).
\end_layout

\begin_layout Section
Release policy
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Release policy
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Starting with version 2.4.0 SDCC in 2004 uses a time-based release schedule with one official release usually during the first half of the year.
\end_layout

\begin_layout Standard
The last digit of an official release is zero.
 Additionally there are daily snapshots available at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/snap.php
\end_layout

\end_inset

,
 and you can always build the very last version from the source code available at Sourceforge 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/snap.php#Source
\end_layout

\end_inset

.
 The SDCC Wiki
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
wiki
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
SDCC Wiki
\end_layout

\end_inset

 at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/wiki/
\end_layout

\end_inset

 also holds some information about past and future releases.
\end_layout

\begin_layout Section
Quality control
\begin_inset CommandInset label
LatexCommand label
name "sec:Quality-control"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Quality control
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The compiler is passed through 
\shape italic
daily
\shape default
 snapshot build compile and build checks.
 The so called 
\shape italic
regression tests
\shape default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Regression test
\end_layout

\end_inset

 check that SDCC itself compiles flawlessly on several host platforms (i386,
 Opteron,
 64 bit Alpha,
 ppc64,
 Mac OS X on ppc and i386,
 Solaris on Sparc) and checks the quality of the code generated by SDCC by running the code for several target platforms through simulators.
 The regression test suite comprises about 1000 files which expand to more than 1500 test cases which include about 7000 tests.
 A large number of tests from the GCC test suite is included in this.
 The results of these tests are published daily on SDCC's snapshot page (click on the red or green symbols on the right side of 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/snap.php
\end_layout

\end_inset

).
\end_layout

\begin_layout Standard
You'll find the test code in the directory 
\shape italic
sdcc/support/regression
\shape default
.
 You can run these tests manually by running 
\family sans
make
\family default
 in this directory (or f.e.
 
\family sans
\series bold

\begin_inset Quotes sld
\end_inset

make test-mcs51
\begin_inset Quotes srd
\end_inset


\family default
\series default
 if you don't want to run the complete tests).
 The test code might also be interesting if you want to look for examples
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Examples
\end_layout

\end_inset

 checking corner cases of SDCC or if you plan to submit patches
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Patch submission
\end_layout

\end_inset

.
\end_layout

\begin_layout Standard
The PIC14 port uses a different set of regression tests 
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Regression test (PIC14)
\end_layout

\end_inset

,
 you'll find them in the directory 
\shape italic
sdcc/src/regression
\shape default
.
\end_layout

\begin_layout Section
Examples
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Examples
\end_layout

\end_inset


\end_layout

\begin_layout Standard
You'll find some small examples in the directory 
\emph on
sdcc/device/examples/.

\emph default
 More examples and libraries are available at 
\emph on
The SDCC Open Knowledge Resource 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdccokr.dl9sec.de/
\end_layout

\end_inset


\emph default
 web site or at 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.pjrc.com/tech/8051/
\end_layout

\end_inset

.
\end_layout

\begin_layout Standard
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
I did insert a reference to Paul's web site here although it seems rather dedicated to a specific 8032 board (I think it's okay because it f.e.
 shows LCD/Harddisc interface and has a free 8051 monitor.
 Independent 8032 board vendors face hard competition of heavily subsidized development boards anyway).
\end_layout

\begin_layout Plain Layout
Maybe we should include some links to real world applications.
 Preferably pointer to pointers (one for each architecture) so this stays manageable here?
\end_layout

\end_inset


\end_layout

\begin_layout Section
Use of SDCC in Education
\end_layout

\begin_layout Standard
In short:
 
\emph on
highly
\emph default
 encouraged
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
the phrase "use in education" might evoke the association "
\emph on
only
\emph default
 fit for use in education".
 This connotation is not intended but nevertheless risked as the licensing of SDCC makes it difficult to offer educational discounts
\end_layout

\end_inset

.
 If your rationales are to:
\end_layout

\begin_layout Enumerate
give students a chance to understand the 
\emph on
complete
\emph default
 steps of code generation
\end_layout

\begin_layout Enumerate
have a curriculum that can be extended for years.
 Then you could use an FPGA board as target and your curriculum will seamlessly extend from logic synthesis (http://www.opencores.org 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

opencores.org
\end_layout

\end_inset

,
 Oregano 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.oregano.at/ip/ip01.htm
\end_layout

\end_inset

),
 over assembly programming,
 to C to FPGA compilers (FPGAC 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/projects/fpgac/
\end_layout

\end_inset

) and to C.
\end_layout

\begin_layout Enumerate
be able to insert excursions about skills like using a revision control system,
 submitting/applying patches,
 using a type-setting (as opposed to word-processing) engine \SpecialChar LyX
/\SpecialChar LaTeX
,
 using SourceForge 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/
\end_layout

\end_inset

,
 following some netiquette 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://en.wikipedia.org/wiki/Netiquette
\end_layout

\end_inset

,
 understanding BSD/LGPL/GPL/Proprietary licensing,
 growth models of Open Source Software,
 CPU simulation,
 compiler regression tests
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Regression test
\end_layout

\end_inset

.
 
\begin_inset Newline newline
\end_inset

And if there should be a shortage of ideas then you can always point students to the ever-growing feature request list 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/p/sdcc/feature-requests/
\end_layout

\end_inset

.
\end_layout

\begin_layout Enumerate
not tie students to a specific host platform and instead allow them to use a host platform of 
\emph on
their
\emph default
 choice (among them Alpha,
 i386,
 i386_64,
 Mac OS X,
 Mips,
 Sparc,
 Windows and eventually OLPC 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://www.laptop.org
\end_layout

\end_inset

)
\end_layout

\begin_layout Enumerate
not encourage students to use illegal copies of educational software
\end_layout

\begin_layout Enumerate
be immune to licensing/availability/price changes of the chosen tool chain
\end_layout

\begin_layout Enumerate
be able to change to a new target platform without having to adopt a new tool chain
\end_layout

\begin_layout Enumerate
have complete control over and insight into the tool chain
\end_layout

\begin_layout Enumerate
make your students aware about the pros and cons of open source software development
\end_layout

\begin_layout Enumerate
give back to the public as you are probably at least partially publicly funded
\end_layout

\begin_layout Enumerate
give students a chance to publicly prove their skills and to possibly see a world wide impact
\end_layout

\begin_layout Standard
then SDCC is probably among the first choices.
 Well,
 probably SDCC might be the only choice.
\end_layout

\begin_layout Chapter
SDCC Technical Data
\end_layout

\begin_layout Section
Optimizations
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Optimizations
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC performs a host of standard optimizations in addition to some MCU specific optimizations.
 
\end_layout

\begin_layout Subsection
Sub-expression Elimination
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Subexpression elimination
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The compiler does local and 
\emph on
g
\emph default
lobal 
\emph on
c
\emph default
ommon 
\emph on
s
\emph default
ubexpression 
\emph on
e
\emph default
limination,
 e.g.:
 
\end_layout

\begin_layout Verse

\family typewriter
i = x + y + 1;
\begin_inset Newline newline
\end_inset

j = x + y;
\end_layout

\begin_layout Standard
will be translated to
\end_layout

\begin_layout Verse

\family typewriter
iTemp = x + y;
\begin_inset Newline newline
\end_inset

i = iTemp + 1;
\begin_inset Newline newline
\end_inset

j = iTemp;
\end_layout

\begin_layout Standard
Some subexpressions are not as obvious as the above example,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
a->b[i].c = 10;
\begin_inset Newline newline
\end_inset

a->b[i].d = 11;
\end_layout

\begin_layout Standard
In this case the address arithmetic a->b[i] will be computed only once;
 the equivalent code in C would be.
\end_layout

\begin_layout Verse

\family typewriter
iTemp = a->b[i];
\begin_inset Newline newline
\end_inset

iTemp.c = 10;
\begin_inset Newline newline
\end_inset

iTemp.d = 11;
\end_layout

\begin_layout Standard
The compiler will try to keep these temporary variables in registers.
\end_layout

\begin_layout Subsection
Dead-Code Elimination
\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
Dead-code elimination
\end_layout

\end_inset


\end_layout

\begin_layout Verse

\family typewriter
int global;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void f () {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

int i;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

i = 1;
 
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* dead store */
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

global = 1;
\begin_inset space ~
\end_inset

/* dead store */
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

global = 2;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

global = 3;
\begin_inset space ~
\end_inset

/* unreachable */
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
will be changed to
\end_layout

\begin_layout Verse

\family typewriter
int global;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

void f () {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

global = 2;
 
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Subsection
Copy-Propagation
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Copy propagation
\end_layout

\end_inset


\end_layout

\begin_layout Verse

\family typewriter
int f() {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

int i,
 j;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

i = 10;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

j = i;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return j;
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
will be changed to 
\end_layout

\begin_layout Verse

\family typewriter
int f() {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

int i,
 j;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

i = 10;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

j = 10;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return 10;
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
Note:
 the dead stores created by this copy propagation will be eliminated by dead-code elimination.
\end_layout

\begin_layout Subsection
Loop Optimizations
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Loop optimization
\end_layout

\end_inset


\begin_inset CommandInset label
LatexCommand label
name "subsec:Loop-Optimizations"

\end_inset


\end_layout

\begin_layout Standard
Two types of loop optimizations are done by SDCC 
\emph on
loop invariant
\emph default
 lifting and 
\emph on
strength reduction
\emph default
 of loop induction variables.
 In addition to the strength reduction the optimizer marks the induction variables and the register allocator tries to keep the induction variables in registers for the duration of the loop.
 Because of this preference of the register allocator
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Register allocation
\end_layout

\end_inset

,
 loop induction optimization causes an increase in register pressure,
 which may cause unwanted spilling of other temporary variables into the stack
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
stack
\end_layout

\end_inset

 / data space.
 The compiler will generate a warning message when it is forced to allocate extra space either on the stack or data space.
 If this extra space allocation is undesirable then induction optimization can be eliminated either for the entire source file (with -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-noinduction option) or for a given function only using #pragma
\begin_inset space ~
\end_inset

noinduction
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
#
\end_layout

\end_inset

pragma noinduction
\end_layout

\end_inset

.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Loop Invariant:
\end_layout

\begin_layout Verse

\family typewriter
for (i = 0 ;
 i < 100 ;
 i ++)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

f += k + l;
\end_layout

\begin_layout Standard
changed to
\end_layout

\begin_layout Verse

\family typewriter
itemp = k + l;
\begin_inset Newline newline
\end_inset

for (i = 0;
 i < 100;
 i++)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

f += itemp;
\end_layout

\begin_layout Standard
As mentioned previously some loop invariants are not as apparent,
 all static address computations are also moved out of the loop.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Strength Reduction
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Strength reduction
\end_layout

\end_inset

,
 this optimization substitutes an expression by a cheaper expression:
\end_layout

\begin_layout Verse

\family typewriter
for (i=0;i < 100;
 i++)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ar[i*5] = i*3;
\end_layout

\begin_layout Standard
changed to
\end_layout

\begin_layout Verse

\family typewriter
itemp1 = 0;
\begin_inset Newline newline
\end_inset

itemp2 = 0;
\begin_inset Newline newline
\end_inset

for (i=0;i< 100;i++) {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ar[itemp1] = itemp2;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

itemp1 += 5;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

itemp2 += 3;
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
The more expensive multiplication
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Multiplication
\end_layout

\end_inset

 is changed to a less expensive addition.
\end_layout

\begin_layout Subsection
Loop Reversing
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Loop reversing
\end_layout

\end_inset


\end_layout

\begin_layout Standard
This optimization is done to reduce the overhead of checking loop boundaries for every iteration.
 Some simple loops can be reversed and implemented using a 
\begin_inset Quotes eld
\end_inset

decrement and jump if not zero
\begin_inset Quotes erd
\end_inset

 instruction.
 SDCC checks for the following criterion to determine if a loop is reversible (note:
 more sophisticated compilers use data-dependency analysis to make this determination,
 SDCC uses a more simple minded analysis).
\end_layout

\begin_layout Itemize
The 'for' loop is of the form 
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\family typewriter
for(<symbol> = <expression>;
 <sym> [< | <=] <expression>;
 [<sym>++ | <sym> += 1])
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

<for body>
\end_layout

\begin_layout Itemize
The <for body> does not contain 
\begin_inset Quotes eld
\end_inset

continue
\begin_inset Quotes erd
\end_inset

 or 'break
\begin_inset Quotes erd
\end_inset

.
\end_layout

\begin_layout Itemize
All goto's are contained within the loop.
\end_layout

\begin_layout Itemize
No function calls within the loop.
\end_layout

\begin_layout Itemize
The loop control variable <sym> is not assigned any value within the loop
\end_layout

\begin_layout Itemize
The loop control variable does NOT participate in any arithmetic operation within the loop.
\end_layout

\begin_layout Itemize
There are NO switch statements in the loop.
\end_layout

\begin_layout Subsection
Algebraic Simplifications
\end_layout

\begin_layout Standard
SDCC does numerous algebraic simplifications,
 the following is a small sub-set of these optimizations.
\end_layout

\begin_layout Verse

\family typewriter
i = j + 0;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 /* changed to:
 */
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 i = j;
\begin_inset Newline newline
\end_inset

i /= 2;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 /* for unsigned i changed to:
 */
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 i >>= 1;
\begin_inset Newline newline
\end_inset

i = j - j;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 /* changed to:
 */
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 i = 0;
\begin_inset Newline newline
\end_inset

i = j / 1;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 /* changed to:
 */
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 i = j;
\end_layout

\begin_layout Standard
Note the subexpressions
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Subexpression
\end_layout

\end_inset

 given above are generally introduced by macro expansions or as a result of copy/constant propagation.
\end_layout

\begin_layout Subsection
'switch' Statements
\begin_inset CommandInset label
LatexCommand label
name "subsec:'switch'-Statements"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
switch statement
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC can optimize switch statements to jump tables
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
jump tables
\end_layout

\end_inset

.
 It makes the decision based on an estimate of the generated code size.
 SDCC is quite liberal in the requirements for jump table generation:
 
\end_layout

\begin_layout Itemize
The labels need not be in order,
 and the starting number need not be one or zero,
 the case labels are in numerical sequence or not too many case labels are missing.
\begin_inset Separator latexpar
\end_inset


\end_layout

\begin_deeper
\begin_layout Verse

\family typewriter
switch(i) {
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

switch (i) {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 4:
 ...
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 0:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 5:
 ...
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 1:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 3:
 ...
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 6:
 ...
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 3:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 7:
 ...
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 4:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 8:
 ...
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 5:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 9:
 ...
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 6:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 10:
 ...
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 7:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 11:
 ...
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 8:
 ...
\begin_inset Newline newline
\end_inset

}
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

}
\end_layout

\begin_layout Standard
Both the above switch statements will be implemented using a jump-table.
 The example to the right side is slightly more efficient as the check for the lower boundary of the jump-table is not needed.
\end_layout

\end_deeper
\begin_layout Itemize
The number of case labels is not larger than supported by the target architecture.
\end_layout

\begin_layout Itemize
If the case labels are not in numerical sequence ('gaps' between cases) SDCC checks whether a jump table with additionally inserted dummy cases is still attractive.
 
\end_layout

\begin_layout Itemize
If the starting number is not zero and a check for the lower boundary of the jump-table can thus be eliminated SDCC might insert dummy cases 0,
 ...
 .
\end_layout

\begin_layout Standard
Switch statements which have large gaps in the numeric sequence or those that have too many case labels can be split into more than one switch statement for efficient code generation,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
switch (i) {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 1:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 2:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 3:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 4:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 5:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 6:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 7:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 101:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 102:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 103:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 104:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 105:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 106:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 107:
 ...
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
If the above switch statement is broken down into two switch statements
\end_layout

\begin_layout Verse

\family typewriter
switch (i) {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 1:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 2:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 3:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 4:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 5:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 6:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 7:
 ...
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
and
\end_layout

\begin_layout Verse

\family typewriter
switch (i) {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 101:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 102:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 103:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 104:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 105:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 106:
 ...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

case 107:
 ...
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
then both the switch statements will be implemented using jump-tables whereas the unmodified switch statement will not be.
\end_layout

\begin_layout Standard
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
There might be reasons which SDCC cannot know about to either favour or not favour jump tables.
 If the target system has to be as quick for the last switch case as for the first (pro jump table),
 or if the switch argument is known to be zero in the majority of the cases (contra jump table).
\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Bit-shifting Operations
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Bit shifting
\end_layout

\end_inset

.
\end_layout

\begin_layout Standard
Bit shifting is one of the most frequently used operation in embedded programming.
 SDCC tries to implement bit-shift operations in the most efficient way possible,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
unsigned char i;
\begin_inset Newline newline
\end_inset

...
\begin_inset Newline newline
\end_inset

i >>= 4;
\begin_inset Newline newline
\end_inset

...
\end_layout

\begin_layout Standard
generates the following code:
\end_layout

\begin_layout Verse

\family typewriter
mov
\begin_inset space ~
\end_inset

 a,_i
\begin_inset Newline newline
\end_inset

swap a
\begin_inset Newline newline
\end_inset

anl
\begin_inset space ~
\end_inset

 a,#0x0f
\begin_inset Newline newline
\end_inset

mov
\begin_inset space ~
\end_inset

 _i,a
\end_layout

\begin_layout Standard
Typically,
 SDCC will not setup a loop if the shift count is known.
 Another example:
\end_layout

\begin_layout Verse

\family typewriter
unsigned int i;
\begin_inset Newline newline
\end_inset

...
\begin_inset Newline newline
\end_inset

i >>= 9;
\begin_inset Newline newline
\end_inset

...
\end_layout

\begin_layout Standard
will generate:
\end_layout

\begin_layout Verse

\family typewriter
mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,(_i + 1)
\begin_inset Newline newline
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

(_i + 1),#0x00
\begin_inset Newline newline
\end_inset

clr
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

c
\begin_inset Newline newline
\end_inset

rrc
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a
\begin_inset Newline newline
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

_i,a
\end_layout

\begin_layout Subsection
Bit-rotation
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Bit rotation
\end_layout

\end_inset


\end_layout

\begin_layout Standard
A special case of the bit-shift operation is bit rotation
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
rotating bits
\end_layout

\end_inset

,
 SDCC recognizes the following expression to be a left bit-rotation:
\end_layout

\begin_layout Verse

\family typewriter
\series bold
unsigned
\series default

\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

char i;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* unsigned is needed for rotation */
\begin_inset Newline newline
\end_inset

...
\begin_inset Newline newline
\end_inset

i = ((i << 1) | (i >> 7));
\family default

\begin_inset Newline newline
\end_inset


\family typewriter
...
\end_layout

\begin_layout Standard
will generate the following code:
\end_layout

\begin_layout Verse

\family typewriter
mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a,_i
\begin_inset Newline newline
\end_inset

rl
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

a
\begin_inset Newline newline
\end_inset

mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

_i,a
\end_layout

\begin_layout Standard
SDCC uses pattern matching on the parse tree to determine this operation.Variations of this case will also be recognized as bit-rotation,
 i.e.:
 
\end_layout

\begin_layout Verse

\family typewriter
i = ((i >> 7) | (i << 1));
 /* left-bit rotation */
\end_layout

\begin_layout Subsection
Nibble and Byte Swapping
\end_layout

\begin_layout Standard
Other special cases of the bit-shift operations are nibble or byte swapping
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
swapping nibbles/bytes
\end_layout

\end_inset

,
 SDCC recognizes the following expressions:
\end_layout

\begin_layout Verse

\family typewriter
\series bold
unsigned
\series default

\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

char i;
\begin_inset Newline newline
\end_inset


\series bold
unsigned
\series default

\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

int j;
\begin_inset Newline newline
\end_inset

...
\begin_inset Newline newline
\end_inset

i = ((i << 4) | (i >> 4));

\family default
 
\begin_inset Newline newline
\end_inset


\family typewriter
j = ((j << 8) | (j >> 8));
 
\end_layout

\begin_layout Standard
and generates a swap instruction for the nibble swapping
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Nibble swapping
\end_layout

\end_inset

 or move instructions for the byte swapping
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Byte swapping
\end_layout

\end_inset

.
 The 
\begin_inset Quotes sld
\end_inset

j
\begin_inset Quotes srd
\end_inset

 example can be used to convert from little to big-endian or vice versa.
 If you want to change the endianness of a 
\emph on
signed
\emph default
 integer you have to cast to 
\family typewriter
(unsigned int)
\family default
 first.
\end_layout

\begin_layout Standard
Note that SDCC stores numbers in little-endian
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
Usually 8-bit processors don't care much about endianness.
 This is not the case for the standard 8051 which only has an instruction to increment its 
\emph on
dptr
\emph default

\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
DPTR
\end_layout

\end_inset

-datapointer so little-endian is the more efficient byte order.
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
little-endian
\end_layout

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Endianness
\end_layout

\end_inset

 format (i.e.
 lowest order first) for most backends.
 However,
 the hc08,
 s08 and stm8 backends are big-endian.
\end_layout

\begin_layout Subsection
Getting a Bit
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Any Order Bit
\end_layout

\end_inset


\end_layout

\begin_layout Standard
It is frequently required to obtain the highest order bit of an integral type (long,
 int,
 short or char types).
 Also obtaining any other order bit is not uncommon.
 SDCC recognizes the following expressions to yield the highest order bit and generates optimized code for it,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
unsigned int gint;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

foo () {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

unsigned char hob1,
 aob1;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

bit hob2,
 hob3,
 aob2,
 aob3;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

hob1 = (gint >> 15) & 1;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

hob2 = (gint >> 15) & 1;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

hob3 = gint & 0x8000;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

aob1 = (gint >> 9) & 1;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

aob2 = (gint >> 8) & 1;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

aob3 = gint & 0x0800;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
will generate the following code:
\end_layout

\begin_layout Verse

\family typewriter
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 61 ;
\begin_inset space ~
\end_inset

 hob.c 7
\begin_inset Newline newline
\end_inset

000A E5*01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 62
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a,(_gint + 1)
\begin_inset Newline newline
\end_inset

000C 23
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 63
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 rl
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a
\begin_inset Newline newline
\end_inset

000D 54 01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 64
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 anl
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a,#0x01
\begin_inset Newline newline
\end_inset

000F F5*02
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 65
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 _foo_hob1_1_1,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 66 ;
\begin_inset space ~
\end_inset

 hob.c 8
\begin_inset Newline newline
\end_inset

0011 E5*01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset

 67
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a,(_gint + 1)
\begin_inset Newline newline
\end_inset

0013 33
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset

 68
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 rlc
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a
\begin_inset Newline newline
\end_inset

0014 92*00
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset

 69
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 _foo_hob2_1_1,c
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 66 ;
\begin_inset space ~
\end_inset

 hob.c 9
\begin_inset Newline newline
\end_inset

0016 E5*01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset

 67
\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a,(_gint + 1)
\begin_inset Newline newline
\end_inset

0018 33
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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 68
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\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 rlc
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a
\begin_inset Newline newline
\end_inset

0019 92*01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\begin_inset space ~
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 69
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\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 _foo_hob3_1_1,c
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\begin_inset space ~
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 70 ;
\begin_inset space ~
\end_inset

 hob.c 10
\begin_inset Newline newline
\end_inset

001B E5*01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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 71
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 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a,(_gint + 1)
\begin_inset Newline newline
\end_inset

001D 03
\begin_inset space ~
\end_inset


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 72
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 rr
\begin_inset space ~
\end_inset


\begin_inset space ~
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\begin_inset space ~
\end_inset

 a
\begin_inset Newline newline
\end_inset

001E 54 01
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 73
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 anl
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a,#0x01
\begin_inset Newline newline
\end_inset

0020 F5*03
\begin_inset space ~
\end_inset


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 74
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 mov
\begin_inset space ~
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\begin_inset space ~
\end_inset

 _foo_aob1_1_1,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 75 ;
\begin_inset space ~
\end_inset

 hob.c 11
\begin_inset Newline newline
\end_inset

0022 E5*01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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 76
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\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a,(_gint + 1)
\begin_inset Newline newline
\end_inset

0024 13
\begin_inset space ~
\end_inset


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 77
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\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 rrc
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a
\begin_inset Newline newline
\end_inset

0025 92*02
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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 78
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\end_inset


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\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 _foo_aob2_1_1,c
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset

 79 ;
\begin_inset space ~
\end_inset

 hob.c 12
\begin_inset Newline newline
\end_inset

0027 E5*01
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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\end_inset


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\end_inset


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\end_inset


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 80
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\end_inset


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\end_inset


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\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 a,(_gint + 1)
\begin_inset Newline newline
\end_inset

0029 A2 E3
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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\end_inset


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 81
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\end_inset


\begin_inset space ~
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 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 c,acc[3]
\begin_inset Newline newline
\end_inset

002B 92*03
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


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 82
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 mov
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\begin_inset space ~
\end_inset

 _foo_aob3_1_1,c
\end_layout

\begin_layout Standard
Other variations of these cases however will 
\emph on
not
\emph default
 be recognized.
 They are standard C expressions,
 so I heartily recommend these be the only way to get the highest order bit,
 (it is portable).
 Of course it will be recognized even if it is embedded in other expressions,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
xyz = gint + ((gint >> 15) & 1);
\end_layout

\begin_layout Standard
will still be recognized.
\end_layout

\begin_layout Subsection
Higher Order Byte
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Higher Order Byte
\end_layout

\end_inset

 / Higher Order Word
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Higher Order Word
\end_layout

\end_inset


\end_layout

\begin_layout Standard
It is also frequently required to obtain a higher order byte or word of a larger integral type (long,
 int or short types).
 For mcs51,
 SDCC recognizes the following expressions to yield the higher order byte or word and generates optimized code for it,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
unsigned int gint;
\begin_inset Newline newline
\end_inset

unsigned long int glong;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

foo () {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

unsigned char hob1,
 hob2;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

unsigned int how1,
 how2;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

hob1 = (gint >> 8) & 0xFF;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

hob2 = glong >> 24;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

how1 = (glong >> 16) & 0xFFFF;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

how2 = glong >> 8;
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

...
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
will generate the following code:
\end_layout

\begin_layout Verse

\family typewriter
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 91 ;
\begin_inset space ~
\end_inset

 hob.c 15
\begin_inset Newline newline
\end_inset

0037 85*01*06
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 92
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 _foo_hob1_1_1,(_gint + 1)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 93 ;
\begin_inset space ~
\end_inset

 hob.c 16
\begin_inset Newline newline
\end_inset

003A 85*05*07
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 94
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 _foo_hob2_1_1,(_glong + 3)
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 95 ;
\begin_inset space ~
\end_inset

 hob.c 17
\begin_inset Newline newline
\end_inset

003D 85*04*08
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 96
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 _foo_how1_1_1,(_glong + 2)
\begin_inset Newline newline
\end_inset

0040 85*05*09
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 97
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 (_foo_how1_1_1 + 1),(_glong + 3)
\begin_inset Newline newline
\end_inset

0043 85*03*0A
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 98
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 _foo_how2_1_1,(_glong + 1)
\begin_inset Newline newline
\end_inset

0046 85*04*0B
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 99
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 mov
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

 (_foo_how2_1_1 + 1),(_glong + 2)
\end_layout

\begin_layout Standard
Again,
 variations of these cases may 
\emph on
not
\emph default
 be recognized.
 They are standard C expressions,
 so I heartily recommend these be the only way to get the higher order byte/word,
 (it is portable).
 Of course it will be recognized even if it is embedded in other expressions,
 e.g.:
\end_layout

\begin_layout Verse

\family typewriter
xyz = gint + ((gint >> 8) & 0xFF);
\end_layout

\begin_layout Standard
will still be recognized.
\end_layout

\begin_layout Subsection
Placement of Bank-Selection Instructions
\end_layout

\begin_layout Standard
For non-intrinsic named address spaces,
 SDCC will place the bank selection instructions optimally.
 For details see Philipp Klaus Krause,
 
\begin_inset Quotes sld
\end_inset

Optimal Placement of Bank Selection Instructions in Polynomial Time
\begin_inset Quotes srd
\end_inset

,
 Proceedings of the 16th International Workshop on Software and Compilers for Embedded Systems,
 M-SCOPES ’13,
 pp 23–30.
 Association for Computing Machinery,
 2013.
 
\end_layout

\begin_layout Subsection
Lifetime-Optimal Speculative Partial Redundancy Elimination
\end_layout

\begin_layout Standard
SDCC has an implementation of lifetime-optimal speculative partial redundancy elimination based on tree-decompositions.
\end_layout

\begin_layout Subsection
Register Allocation
\begin_inset CommandInset label
LatexCommand label
name "subsec:Register-Allocation"

\end_inset


\begin_inset Index idx
range none
pageformat default
status open

\begin_layout Plain Layout
Register-Allocation
\end_layout

\end_inset


\end_layout

\begin_layout Standard
SDCC currently has two register allocators.
 One of them is optimal when optimizing for code size.
 This register allocator is used by default on all ports except for mcs51,
 ds390,
 pic14 and pic16.
 With the exception of hc08 and s08,
 it is also the only available register allocator for these ports.
 Even though it runs in polynomial time,
 it can be quite slow;
 therefore the 
\begin_inset Flex Code
status open

\begin_layout Plain Layout
--max-allocs-per-node
\end_layout

\end_inset

 command line option can be used for a trade-off between compilation speed and quality of the generated code:
 Lower values result in faster compilation,
 higher values can result in better code being generated.
\end_layout

\begin_layout Standard
It first creates a tree-decomposition of the control-flow graph,
 and then uses dynamic programming bottom-up along the tree-decomposition.
 Optimality is achieved through the use of a cost function,
 which gives cost for instructions under register assignments.
 The cost function is target-specific and has to be implemented for each port;
 in all current SDCC ports the cost function is integrated into code generation.
\end_layout

\begin_layout Standard
For more details on how this register allocator works,
 see:
 Philipp Klaus Krause,
 
\begin_inset Quotes sld
\end_inset

Optimal Register Allocation in Polynomial Time
\begin_inset Quotes srd
\end_inset

,
 Compiler Construction - 22nd International Conference,
 CC 2013,
 Held as Part of the European Joint Conferences on Theory and Practice of Software,
 ETAPS 2013.
 Proceedings,
 Lecture Notes in Computer Science,
 volume 7791,
 pp.
 1-20.
 Springer,
 2013.
 Also:
 Philipp Klaus Krause,
 
\begin_inset Quotes sld
\end_inset

Bytewise Register Allocation
\begin_inset Quotes srd
\end_inset

,
 Proceedings of the 18th International Workshop on Software and Compilers for Embedded Systems,
 SCOPES ’15,
 pp 22–27.
 Association for Computing Machinery,
 2015.
 
\end_layout

\begin_layout Subsection
Peephole Optimizer
\begin_inset CommandInset label
LatexCommand label
name "subsec:Peephole-Optimizer"

\end_inset


\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Peephole optimizer
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The compiler uses a rule based,
 pattern matching and re-writing mechanism for peep-hole optimization.
 It is inspired by 
\emph on
copt
\emph default
 a peep-hole optimizer by Christopher W.
 Fraser (cwfraser
\begin_inset space ~
\end_inset

@
\begin_inset space ~
\end_inset

microsoft.com).
 A default set of rules are compiled into the compiler,
 additional rules may be added with the 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-file
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-file
\end_layout

\end_inset

 <filename>
\emph default
 option.
 The rule language is best illustrated with examples.
\end_layout

\begin_layout Verse

\family typewriter
replace {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov %1,a
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,%1
\begin_inset Newline newline
\end_inset

} by {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov %1,a
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
The above rule will change the following assembly
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Assembler routines
\end_layout

\end_inset

 sequence:
\end_layout

\begin_layout Verse

\family typewriter
mov r1,a
\begin_inset Newline newline
\end_inset

mov a,r1
\end_layout

\begin_layout Standard
to
\end_layout

\begin_layout Verse

\family typewriter
mov r1,a
\end_layout

\begin_layout Standard
Note:
 All occurrences of a 
\emph on
%n
\emph default
 (pattern variable) must denote the same string.
 With the above rule,
 the assembly sequence:
\end_layout

\begin_layout Verse

\family typewriter
mov r1,a
\begin_inset Newline newline
\end_inset

mov a,r2
\end_layout

\begin_layout Standard
will remain unmodified.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Other special case optimizations may be added by the user (via 
\emph on
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-file option
\emph default
).
 E.g.
 some variants of the 8051 MCU
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
MCS51 variants
\end_layout

\end_inset

 allow only 
\family typewriter
ajmp
\family default
 and 
\family typewriter
acall
\family default
.
 The following two rules will change all 
\family typewriter
ljmp
\family default
 and 
\family typewriter
lcall
\family default
 to 
\family typewriter
ajmp
\family default
 and 
\family typewriter
acall
\end_layout

\begin_layout Verse

\family typewriter
replace { lcall %1 } by { acall %1 }
\begin_inset Newline newline
\end_inset

replace { ljmp %1 } by { ajmp %1 }
\end_layout

\begin_layout Standard
(NOTE:
 from version 2.7.3 on,
 you can use option -
\emph on

\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset


\emph default
-acall-ajmp
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-acall-ajmp
\end_layout

\end_inset

,
 which also takes care of aligning the interrupt vectors properly.)
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
The 
\emph on
inline-assembler code
\emph default
 is also passed through the peep hole optimizer,
 thus the peephole optimizer can also be used as an assembly level macro expander.
 The rules themselves are MCU dependent whereas the rule language infra-structure is MCU independent.
 Peephole optimization rules for other MCU can be easily programmed using the rule language.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The syntax for a rule is as follows:
\end_layout

\begin_layout Verse

\family typewriter
rule := replace [ restart ] '{' <assembly sequence> '
\backslash
n'
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 '}' by '{' '
\backslash
n'
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 <assembly sequence> '
\backslash
n'
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 '}' [if <functionName> ] '
\backslash
n'
\end_layout

\begin_layout Standard
<assembly sequence> := assembly instruction (each instruction including labels must be on a separate line).
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The optimizer will apply to the rules one by one from the top in the sequence of their appearance,
 it will terminate when all rules are exhausted.
 If the 'restart' option is specified,
 then the optimizer will start matching the rules again from the top,
 this option for a rule is expensive (performance),
 it is intended to be used in situations where a transformation will trigger the same rule again.
 An example of this (not a good one,
 it has side effects) is the following rule:
\end_layout

\begin_layout Verse

\family typewriter
replace restart {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

pop %1
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

push %1 } by {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

;
 nop
\begin_inset Newline newline
\end_inset

}
\end_layout

\begin_layout Standard
Note that the replace pattern cannot be a blank,
 but can be a comment line.
 Without the 'restart' option only the innermost 'pop' 'push' pair would be eliminated,
 i.e.:
\end_layout

\begin_layout Verse

\family typewriter
pop ar1
\begin_inset Newline newline
\end_inset

pop ar2
\begin_inset Newline newline
\end_inset

push ar2
\begin_inset Newline newline
\end_inset

push ar1
\end_layout

\begin_layout Standard
would result in:
\end_layout

\begin_layout Verse

\family typewriter
pop ar1
\begin_inset Newline newline
\end_inset

;
 nop
\begin_inset Newline newline
\end_inset

push ar1
\end_layout

\begin_layout Standard

\emph on
with
\emph default
 the restart option the rule will be applied again to the resulting code and then all the pop-push pairs will be eliminated to yield:
\end_layout

\begin_layout Verse

\family typewriter
;
 nop
\begin_inset Newline newline
\end_inset

;
 nop
\end_layout

\begin_layout Standard
A conditional function can be attached to a rule.
 Attaching rules are somewhat more involved,
 let's illustrate this with an example.
\end_layout

\begin_layout Verse

\family typewriter
replace {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

ljmp %5
\begin_inset Newline newline
\end_inset

%2:
\begin_inset Newline newline
\end_inset

} by {
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

 
\begin_inset space ~
\end_inset

sjmp %5
\begin_inset Newline newline
\end_inset

%2:
\begin_inset Newline newline
\end_inset

} if labelInRange
\end_layout

\begin_layout Standard
The optimizer does a look-up of a function name table defined in function 
\emph on
callFuncByName
\emph default
 in the source file SDCCpeeph.c,
 with the name 
\emph on
labelInRange
\emph default
.
 If it finds a corresponding entry the function is called.
 Note there can be no parameters specified for some of these functions,
 in this case the use of 
\emph on
%5
\emph default
 is crucial,
 since the function 
\emph on
labelInRange
\emph default
 expects to find the label in that particular variable (the hash table containing the variable bindings is passed as a parameter).
 If you want to code more such functions,
 take a close look at the function labelInRange and the calling mechanism in source file SDCCpeeph.c.
 Currently implemented are 
\emph on
labelInRange,
 labelRefCount,
 labelRefCountChange,
 labelIsReturnOnly,
 xramMovcOption,
 portIsDS390,
 24bitMode,
 notVolatile
\emph default
.
 
\emph on
notUsed,
 notSame,
 operandsNotRelated,
 labelJTInRange,
 canAssign,
 optimizeReturn,
 notUsedFrom,
 labelIsReturnOnly,
 operandsLiteral,
 labelIsUncondJump,
 deadMove,
 useAcallAjmp
\emph default
 and 
\emph on
okToRemoveSLOC.
\end_layout

\begin_layout Standard
This whole thing is a little kludgy,
 but maybe some day SDCC will have some better means.
 If you are looking at the 
\family typewriter
peeph*.def
\family default
 files,
 you will see the default rules that are compiled into the compiler,
 you can add your own rules in the default set there if you get tired of specifying the -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-peep-file option.
\end_layout

\begin_layout Section
Cyclomatic Complexity
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Cyclomatic complexity
\end_layout

\end_inset


\end_layout

\begin_layout Standard
Cyclomatic complexity of a function is defined as the number of independent paths the program can take during execution of the function.
 This is an important number since it defines the number test cases you have to generate to validate the function.
 The accepted industry standard for complexity number is 10,
 if the cyclomatic complexity reported by SDCC exceeds 10 you should think about simplification of the function logic.
 Note that the complexity level is not related to the number of lines of code in a function.
 Large functions can have low complexity,
 and small functions can have large complexity levels.
 
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

SDCC uses the following formula to compute the complexity:
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
complexity = (number of edges in control flow graph) - (number of nodes in control flow graph) + 2;
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Having said that the industry standard is 10,
 you should be aware that in some cases it be may unavoidable to have a complexity level of less than 10.
 For example if you have switch statement with more than 10 case labels,
 each case label adds one to the complexity level.
 The complexity level is by no means an absolute measure of the algorithmic complexity of the function,
 it does however provide a good starting point for which functions you might look at for further optimization.
\end_layout

\begin_layout Section
Retargetting for other Processors
\end_layout

\begin_layout Standard
The issues for retargetting the compiler are far too numerous to be covered by this document.
 What follows is a brief description of each of the phases of the compiler and its MCU dependency.
\end_layout

\begin_layout Itemize
Parsing the source and building the annotated parse tree.
 This phase is largely MCU independent (except for the language extensions).
 Syntax & semantic checks are also done in this phase,
 along with some initial optimizations like back patching labels and the pattern matching optimizations like bit-rotation etc.
\end_layout

\begin_layout Itemize
The second phase involves generating an intermediate code which can be easy manipulated during the later phases.
 This phase is entirely MCU independent.
 The intermediate code generation assumes the target machine has unlimited number of registers,
 and designates them with the name iTemp.
 The compiler can be made to dump a human readable form of the code generated by using the -
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-dumpraw option.
\end_layout

\begin_layout Itemize
This phase does the bulk of the standard optimizations and is also MCU independent.
 This phase can be broken down into several sub-phases:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Break down intermediate code (iCode) into basic blocks.
\begin_inset Newline newline
\end_inset

Do control flow & data flow analysis on the basic blocks.
\begin_inset Newline newline
\end_inset

Do local common subexpression elimination,
 then global subexpression elimination
\begin_inset Newline newline
\end_inset

Dead code elimination
\begin_inset Newline newline
\end_inset

Loop optimizations
\begin_inset Newline newline
\end_inset

If loop optimizations caused any changes then do 'global subexpression elimination' and 'dead code elimination' again.
\end_layout

\begin_layout Itemize
This phase determines the live-ranges;
 by live range I mean those iTemp variables defined by the compiler that still survive after all the optimizations.
 Live range analysis
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Live range analysis
\end_layout

\end_inset

 is essential for register allocation,
 since these computation determines which of these iTemps will be assigned to registers,
 and for how long.
\end_layout

\begin_layout Itemize
Phase five is register allocation.
 For new ports register allocator described above in 
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Register-Allocation"
nolink "false"

\end_inset

 should be used in most cases,
 since it can result in substantially better code.
 In the old register allocator,
 there are two parts to register allocation.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The first part I call 'register packing' (for lack of a better term).
 In this case several MCU specific expression folding is done to reduce register pressure.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The second part is more MCU independent and deals with allocating registers to the remaining live ranges.
 A lot of MCU specific code does creep into this phase because of the limited number of index registers available in the 8051.
\end_layout

\begin_layout Itemize
The Code generation phase is (unhappily),
 entirely MCU dependent and very little (if any at all) of this code can be reused for other MCU.
 However the scheme for allocating a homogenized assembler operand for each iCode operand may be reused.
\end_layout

\begin_layout Itemize
As mentioned in the optimization section the peep-hole optimizer is rule based system,
 which can reprogrammed for other MCUs.
\end_layout

\begin_layout Standard
More information is available on SDCC Wiki
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
wiki
\end_layout

\end_inset

 (preliminary link 
\begin_inset Flex URL
status open

\begin_layout Plain Layout

https://sourceforge.net/p/sdcc/wiki/Adding%20a%20port/
\end_layout

\end_inset

) and in the thread 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/mailarchive/message.php?msg_id=13954144
\end_layout

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 .
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\begin_layout Chapter
Compiler internals
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Compiler internals
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\begin_layout Section
The anatomy of the compiler
\begin_inset CommandInset label
LatexCommand label
name "subsec:The-anatomy-of"

\end_inset


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\begin_layout Standard

\shape italic
This is an excerpt from an article published in Circuit Cellar Magazine in
\shape default
 
\series bold
\shape italic
August 2000
\series default
.
 It's outdated (the compiler is much more efficient now and user/developer friendly),
 but pretty well exposes the guts of it all.
\shape default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

The current version of SDCC can generate code for Intel 8051 and Z80 MCU.
 It is fairly easy to retarget for other 8-bit MCU.
 Here we take a look at some of the internals of the compiler.
 
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Parsing
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Parsing
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\begin_layout Standard
Parsing the input source file and creating an AST (Annotated Syntax Tree
\begin_inset Index idx
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Annotated syntax tree
\end_layout

\end_inset

).
 This phase also involves propagating types (annotating each node of the parse tree with type information) and semantic analysis.
 There are some MCU specific parsing rules.
 For example the intrinsic named address spaces are MCU specific:
 While there may be an __xdata intrinsic named address space for 8051 there none for z80.
 SDCC has MCU specific intrinsic named address spacess,
 i.e.
 __xdata will be treated as a named address space when parsing 8051 C code but will be treated as a C identifier when parsing z80 code.
\end_layout

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Generating iCode
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iCode
\end_layout

\end_inset


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\begin_layout Standard
Intermediate code generation.
 In this phase the AST is broken down into three-operand form (iCode).
 These three operand forms are represented as doubly linked lists.
 ICode is the term given to the intermediate form generated by the compiler.
 ICode example section shows some examples of iCode generated for some simple C source functions.
\end_layout

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Optimizations
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Optimizations
\end_layout

\end_inset

.
\end_layout

\begin_layout Standard
Bulk of the target independent optimizations is performed in this phase.
 The optimizations include constant propagation,
 common sub-expression elimination,
 loop invariant code movement,
 strength reduction of loop induction variables and dead-code elimination.
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Live range analysis
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Live range analysis
\end_layout

\end_inset


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\begin_layout Standard
During intermediate code generation phase,
 the compiler assumes the target machine has infinite number of registers and generates a lot of temporary variables.
 The live range computation determines the lifetime of each of these compiler-generated temporaries.
 A picture speaks a thousand words.
 ICode example sections show the live range annotations for each of the operand.
 It is important to note here,
 each iCode is assigned a number in the order of its execution in the function.
 The live ranges are computed in terms of these numbers.
 The from number is the number of the iCode which first defines the operand and the to number signifies the iCode which uses this operand last.
\end_layout

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Register Allocation
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Register allocation
\end_layout

\end_inset


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\begin_layout Standard
The register allocation determines the type and number of registers needed by each operand.
 In most MCUs only a few registers can be used for indirect addressing.
 In case of 8051 for example the registers R0 & R1 can be used to indirectly address the internal ram and DPTR to indirectly address the external ram.
 The compiler will try to allocate the appropriate register to pointer variables if it can.
 ICode example section shows the operands annotated with the registers assigned to them.
 The compiler will try to keep operands in registers as much as possible;
 there are several schemes the compiler uses to do achieve this.
 When the compiler runs out of registers the compiler will check to see if there are any live operands which is not used or defined in the current basic block being processed,
 if there are any found then it will push that operand and use the registers in this block,
 the operand will then be popped at the end of the basic block.
 
\end_layout

\begin_layout Standard
There are other MCU specific considerations in this phase.
 Some MCUs have an accumulator;
 very short-lived operands could be assigned to the accumulator instead of a general-purpose register.
\end_layout

\begin_layout Paragraph*
Code generation
\end_layout

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Figure II gives a table of iCode
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
iCode
\end_layout

\end_inset

 operations supported by the compiler.
 The code generation involves translating these operations into corresponding assembly code for the processor.
 This sounds overly simple but that is the essence of code generation.
 Some of the iCode operations are generated on a MCU specific manner for example,
 the z80 port does not use registers to pass parameters so the SEND and RECV iCode operations will not be generated,
 and it also does not support JUMPTABLES.
 
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Figure II 
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IC_RESULT = !
 IC_LEFT;
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IC_RESULT = (IC_LEFT << IC_RIGHT) | (IC_LEFT >> (sizeof(IC_LEFT)*8-IC_RIGHT));
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Pop the operand from the stack 
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CALL
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IC_LEFT() IC_RESULT()
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IC_RESULT = IC_LEFT();
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IC_RESULT = (*IC_LEFT)();
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Return the value in operand IC_LEFT 
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IC_RESULT = IC_LEFT + IC_RIGHT
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IC_RESULT = IC_LEFT * IC_RIGHT;
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\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = IC_LEFT == IC_RIGHT;
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
AND_OP
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_LEFT() IC_RIGHT() IC_RESULT() 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Logical and operation
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = IC_LEFT && IC_RIGHT;
 
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
OR_OP
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_LEFT() IC_RIGHT() IC_RESULT() 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Logical or operation 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = IC_LEFT || IC_RIGHT;
 
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
'^'
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_LEFT() IC_RIGHT() IC_RESULT() 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Exclusive OR
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = IC_LEFT ^ IC_RIGHT;
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
'|'
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_LEFT() IC_RIGHT() IC_RESULT() 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Bitwise OR 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = IC_LEFT | IC_RIGHT;
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
BITWISEAND
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_LEFT() IC_RIGHT() IC_RESULT()
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Bitwise AND 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = IC_LEFT & IC_RIGHT;
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
LEFT_OP
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_LEFT() IC_RIGHT() IC_RESULT()
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Left shift 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = IC_LEFT << IC_RIGHT 
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
RIGHT_OP
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_LEFT() IC_RIGHT() IC_RESULT()
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Right shift
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = IC_LEFT >> IC_RIGHT 
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
GET_VALUE_
\begin_inset Newline newline
\end_inset

AT_ ADDRESS
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_LEFT() IC_RESULT()
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Indirect fetch 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = (*IC_LEFT);
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
POINTER_SET
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RIGHT() IC_RESULT() 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Indirect set
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
(*IC_RESULT) = IC_RIGHT;
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
'='
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RIGHT() IC_RESULT()
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Assignment
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = IC_RIGHT;
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IFX
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_COND IC_TRUE IC_LABEL
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Conditional jump.
 If true label is present then jump to true label if condition is true else jump to false label if condition is false 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
if (IC_COND) goto IC_TRUE;
 
\begin_inset Newline newline
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

Or 
\begin_inset Newline newline
\end_inset

If (!IC_COND) goto IC_FALSE;
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
ADDRESS_OF
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_LEFT() IC_RESULT()
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Address of 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = &IC_LEFT();
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
JUMPTABLE
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_JTCOND IC_JTLABELS
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Jump to list of labels depending on the value of JTCOND
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Switch statement
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
CAST
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RIGHT() IC_LEFT() IC_RESULT()
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
Cast types 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT = (typeof IC_LEFT) IC_RIGHT;
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
SEND
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_LEFT()
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
This is used for passing parameters in registers;
 
\begin_inset Newline newline
\end_inset

move IC_LEFT to the next available parameter register.
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
None
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
RECV
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
IC_RESULT()
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
This is used for receiving parameters passed in registers;
\begin_inset Newline newline
\end_inset

Move the values in the next parameter register to IC_RESULT 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
None
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\shape slanted
\size footnotesize
(some more have been added)
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\shape slanted
\size footnotesize
see f.e.

\shape default
 
\family typewriter
\shape slanted
gen51Code()
\family default
\shape default
 
\shape slanted
in
\shape default
 
\family typewriter
\shape slanted
src/mcs51/gen.c
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Note Note
status collapsed

\begin_layout Plain Layout
In the original article Figure II was announced to be downloadable on 
\shape italic
Circuit Cellar
\shape default
's web site.
 ftp://ftp.circuitcellar.com/pub/Circuit_Cellar/2000/121/dutta.ZIP
\end_layout

\end_inset


\end_layout

\begin_layout Paragraph*
ICode Example
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
iCode
\end_layout

\end_inset


\end_layout

\begin_layout Standard
This section shows some details of iCode.
 The example C code does not do anything useful;
 it is used as an example to illustrate the intermediate code generated by the compiler.
\end_layout

\begin_layout Verse

\family typewriter
1.
\begin_inset space ~
\end_inset

__xdata int * p;
\begin_inset Newline newline
\end_inset

2.
\begin_inset space ~
\end_inset

int gint;
\begin_inset Newline newline
\end_inset

3.
\begin_inset space ~
\end_inset

/* This function does nothing useful.
 It is used
\begin_inset Newline newline
\end_inset

4.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

for the purpose of explaining iCode */
\begin_inset Newline newline
\end_inset

5.
\begin_inset space ~
\end_inset

short function (__data int *x)
\begin_inset Newline newline
\end_inset

6.
\begin_inset space ~
\end_inset

{
\begin_inset Newline newline
\end_inset

7.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

short i=10;
 
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* dead initialization eliminated */
\begin_inset Newline newline
\end_inset

8.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

short sum=10;
 /* dead initialization eliminated */
\begin_inset Newline newline
\end_inset

9.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

short mul;
\begin_inset Newline newline
\end_inset

10.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

int j ;
\begin_inset Newline newline
\end_inset

11.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

while (*x) *x++ = *p++;
\begin_inset Newline newline
\end_inset

12.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sum = 0 ;
\begin_inset Newline newline
\end_inset

13.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mul = 0;
\begin_inset Newline newline
\end_inset

14.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* compiler detects i,j to be induction variables */
\begin_inset Newline newline
\end_inset

15.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

for (i = 0,
 j = 10 ;
 i < 10 ;
 i++,
 j
\family default
-
\begin_inset ERT
status collapsed

\begin_layout Plain Layout


\backslash
/
\end_layout

\end_inset

-
\family typewriter
) {
\begin_inset Newline newline
\end_inset

16.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sum += i;
\begin_inset Newline newline
\end_inset

17.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mul += i * 3;
 
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* this multiplication remains */
\begin_inset Newline newline
\end_inset

18.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

gint += j * 3;
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

/* this multiplication changed to addition */
\begin_inset Newline newline
\end_inset

19.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

}
\begin_inset Newline newline
\end_inset

20.
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

return sum+mul;
\begin_inset Newline newline
\end_inset

21.
\begin_inset space ~
\end_inset

}
\end_layout

\begin_layout Standard
In addition to the operands each iCode contains information about the filename and line it corresponds to in the source file.
 The first field in the listing should be interpreted as follows:
\begin_inset Newline newline
\end_inset


\shape italic
\size footnotesize
Filename(linenumber:
 iCode Execution sequence number :
 ICode hash table key :
 loop depth of the iCode).
\shape default
\size default

\begin_inset Newline newline
\end_inset

Then follows the human readable form of the ICode operation.
 Each operand of this triplet form can be of three basic types a) compiler generated temporary b) user defined variable c) a constant value.
 Note that local variables and parameters are replaced by compiler generated temporaries.
 Live ranges
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Live range analysis
\end_layout

\end_inset

 are computed only for temporaries (i.e.
 live ranges are not computed for global variables).
 Registers
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Register allocation
\end_layout

\end_inset

 are allocated for temporaries only.
 Operands are formatted in the following manner:
\begin_inset Newline newline
\end_inset


\shape italic
\size footnotesize
Operand Name [lr live-from :
 live-to ] { type information } [ registers allocated ].
\shape default
\size default

\begin_inset Newline newline
\end_inset

As mentioned earlier the live ranges are computed in terms of the execution sequence number of the iCodes,
 for example 
\begin_inset Newline newline
\end_inset

the iTemp0 is live from (i.e.
 first defined in iCode with execution sequence number 3,
 and is last used in the iCode with sequence number 5).
 For induction variables such as iTemp21 the live range computation extends the lifetime from the start to the end of the loop.
\begin_inset Newline newline
\end_inset

The register allocator used the live range information to allocate registers,
 the same registers may be used for different temporaries if their live ranges do not overlap,
 for example r0 is allocated to both iTemp6 and to iTemp17 since their live ranges do not overlap.
 In addition the allocator also takes into consideration the type and usage of a temporary,
 for example itemp6 is a pointer to near space and is used as to fetch data from (i.e.
 used in GET_VALUE_AT_ADDRESS) so it is allocated a pointer register (r0).
 Some short lived temporaries are allocated to special registers which have meaning to the code generator e.g.
 iTemp13 is allocated to a pseudo register CC which tells the back end that the temporary is used only for a conditional jump the code generation makes use of this information to optimize a compare and jump ICode.
\begin_inset Newline newline
\end_inset

There are several loop optimizations
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Loop optimization
\end_layout

\end_inset

 performed by the compiler.
 It can detect induction variables iTemp21(i) and iTemp23(j).
 Also note the compiler does selective strength reduction
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Strength reduction
\end_layout

\end_inset

,
 i.e.
 the multiplication of an induction variable in line 18 (gint = j * 3) is changed to addition,
 a new temporary iTemp17 is allocated and assigned a initial value,
 a constant 3 is then added for each iteration of the loop.
 The compiler does not change the multiplication
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Multiplication
\end_layout

\end_inset

 in line 17 however since the processor does support an 8 * 8 bit multiplication.
\begin_inset Newline newline
\end_inset

Note the dead code elimination
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Dead-code elimination
\end_layout

\end_inset

 optimization eliminated the dead assignments in line 7 & 8 to I and sum respectively.
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard

\size footnotesize
Sample.c (5:1:0:0) _entry($9) :
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(5:2:1:0) proc _function [lr0:0]{function short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:3:2:0) iTemp0 [lr3:5]{_near * int}[r2] = recv 
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:4:53:0) preHeaderLbl0($11) :
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:5:55:0) iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near * int}[r2]
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:6:5:1) _whilecontinue_0($1) :
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:7:7:1) iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near * int}[r0]]
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:8:8:1) if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:9:14:1) iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far * int}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:10:15:1) _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2 {short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:13:18:1) iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far * int}[DPTR]]
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:14:19:1) *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int}[r2 r3]
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:15:12:1) iTemp6 [lr5:16]{_near * int}[r0] = iTemp6 [lr5:16]{_near * int}[r0] + 0x2 {short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:16:20:1) goto _whilecontinue_0($1)
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(11:17:21:0)_whilebreak_0($3) :
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(12:18:22:0) iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(13:19:23:0) iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(15:20:54:0)preHeaderLbl1($13) :
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(15:21:56:0) iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(15:22:57:0) iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(15:23:58:0) iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(15:24:26:1)_forcond_0($4) :
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(15:25:27:1) iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4] < 0xa {short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(15:26:28:1) if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(16:27:31:1) iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2] + ITemp21 [lr21:38]{short}[r4]
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(17:29:33:1) iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4] * 0x3 {short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(17:30:34:1) iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3] + iTemp15 [lr29:30]{short}[r1]
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(18:32:36:1:1) iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7 r0]- 0x3 {short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(18:33:37:1) _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{int}[r7 r0]
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(15:36:42:1) iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4] + 0x1 {short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(15:37:45:1) iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5 r6]- 0x1 {short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(19:38:47:1) goto _forcond_0($4)
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(19:39:48:0)_forbreak_0($7) :
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(20:40:49:0) iTemp24 [lr40:41]{short}[DPTR] = iTemp2 [lr18:40]{short}[r2] + ITemp11 [lr19:40]{short}[r3]
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(20:41:50:0) ret iTemp24 [lr40:41]{short}
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(20:42:51:0)_return($8) :
\end_layout

\begin_layout Standard

\size footnotesize
Sample.c(20:43:52:0) eproc _function [lr0:0]{ ia0 re0 rm0}{function short}
\size default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Finally the code generated for this function:
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard

\size footnotesize
.area DSEG (DATA)
\end_layout

\begin_layout Standard

\size footnotesize
_p::
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.ds 2
\end_layout

\begin_layout Standard

\size footnotesize
_gint::
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

.ds 2
\end_layout

\begin_layout Standard

\size footnotesize
;
 sample.c 5
\end_layout

\begin_layout Standard

\size footnotesize
;
 —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
-
\end_layout

\begin_layout Standard

\size footnotesize
;
 function function
\end_layout

\begin_layout Standard

\size footnotesize
;
 —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
-
\end_layout

\begin_layout Standard

\size footnotesize
_function:
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp0 [lr3:5]{_near * int}[r2] = recv 
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r2,dpl
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near * int}[r2]
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov ar0,r2
\end_layout

\begin_layout Standard

\size footnotesize
;_whilecontinue_0($1) :
\end_layout

\begin_layout Standard

\size footnotesize
00101$:
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near * int}[r0]]
\end_layout

\begin_layout Standard

\size footnotesize
;
 if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov ar2,@r0
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc r0
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov ar3,@r0
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dec r0
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r2
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

orl a,r3
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

jz 00103$
\end_layout

\begin_layout Standard

\size footnotesize
00114$:
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far * int}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov dpl,_p
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov dph,(_p + 1)
\end_layout

\begin_layout Standard

\size footnotesize
;
 _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2 {short}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,#0x02
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add a,_p
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov _p,a
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

clr a
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

addc a,(_p + 1)
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov (_p + 1),a
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far * int}[DPTR]]
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

movx a,@dptr
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r2,a
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc dptr
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

movx a,@dptr
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r3,a
\end_layout

\begin_layout Standard

\size footnotesize
;
 *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int}[r2 r3]
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov @r0,ar2
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc r0
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov @r0,ar3
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp6 [lr5:16]{_near * int}[r0] = 
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp6 [lr5:16]{_near * int}[r0] + 
\end_layout

\begin_layout Standard

\size footnotesize
;
 0x2 {short}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc r0
\end_layout

\begin_layout Standard

\size footnotesize
;
 goto _whilecontinue_0($1)
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sjmp 00101$
\end_layout

\begin_layout Standard

\size footnotesize
;
 _whilebreak_0($3) :
\end_layout

\begin_layout Standard

\size footnotesize
00103$:
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r2,#0x00
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r3,#0x00
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r4,#0x00
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r5,#0x0A
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r6,#0x00
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r7,#0x1E
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r0,#0x00
\end_layout

\begin_layout Standard

\size footnotesize
;
 _forcond_0($4) :
\end_layout

\begin_layout Standard

\size footnotesize
00104$:
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4] < 0xa {short}
\end_layout

\begin_layout Standard

\size footnotesize
;
 if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

clr c
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r4
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

xrl a,#0x80
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

subb a,#0x8a
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

jnc 00107$
\end_layout

\begin_layout Standard

\size footnotesize
00115$:
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2] + 
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp21 [lr21:38]{short}[r4]
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r4
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add a,r2
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r2,a
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4] * 0x3 {short}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov b,#0x03
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r4
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mul ab
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r1,a
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3] + 
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp15 [lr29:30]{short}[r1]
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add a,r3
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r3,a
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7 r0]- 0x3 {short}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r7
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add a,#0xfd
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r7,a
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r0
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

addc a,#0xff
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov r0,a
\end_layout

\begin_layout Standard

\size footnotesize
;
 _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{int}[r7 r0]
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r7
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add a,_gint
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov _gint,a
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r0
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

addc a,(_gint + 1)
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov (_gint + 1),a
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4] + 0x1 {short}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

inc r4
\end_layout

\begin_layout Standard

\size footnotesize
;
 iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5 r6]- 0x1 {short}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dec r5
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

cjne r5,#0xff,00104$
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

dec r6
\end_layout

\begin_layout Standard

\size footnotesize
;
 goto _forcond_0($4)
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

sjmp 00104$
\end_layout

\begin_layout Standard

\size footnotesize
;
 _forbreak_0($7) :
\end_layout

\begin_layout Standard

\size footnotesize
00107$:
\end_layout

\begin_layout Standard

\size footnotesize
;
 ret iTemp24 [lr40:41]{short}
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov a,r3
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

add a,r2
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

mov dpl,a
\end_layout

\begin_layout Standard

\size footnotesize
;
 _return($8) :
\end_layout

\begin_layout Standard

\size footnotesize
00108$:
\end_layout

\begin_layout Standard

\size footnotesize
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

ret
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Section
A few words about basic block successors,
 predecessors and dominators
\end_layout

\begin_layout Standard
Successors are basic blocks
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Basic blocks
\end_layout

\end_inset

 that might execute after this basic block.
\begin_inset Newline newline
\end_inset

Predecessors are basic blocks that might execute before reaching this basic block.
\begin_inset Newline newline
\end_inset

Dominators are basic blocks that WILL execute before reaching this basic block.
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
[basic block 1]
\end_layout

\begin_layout Standard
if (something)
\end_layout

\begin_layout Standard
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

[basic block 2]
\end_layout

\begin_layout Standard
else
\end_layout

\begin_layout Standard
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

[basic block 3]
\end_layout

\begin_layout Standard
[basic block 4]
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
a) succList of [BB2] = [BB4],
 of [BB3] = [BB4],
 of [BB1] = [BB2,BB3]
\end_layout

\begin_layout Standard
b) predList of [BB2] = [BB1],
 of [BB3] = [BB1],
 of [BB4] = [BB2,BB3]
\end_layout

\begin_layout Standard
c) domVect of [BB4] = BB1 ...
 here we are not sure if BB2 or BB3 was executed but we are SURE that BB1 was executed.
\end_layout

\begin_layout Chapter
Acknowledgments
\end_layout

\begin_layout Standard
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sdcc.sourceforge.net/#Who
\end_layout

\end_inset


\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\emph on
Thanks to all the other volunteer developers who have helped with coding,
 testing,
 web-page creation,
 distribution sets,
 etc.
 You know who you are :-)
\emph default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\emph on
Thanks to Sourceforge 
\begin_inset Flex URL
status collapsed

\begin_layout Plain Layout

http://sourceforge.net/
\end_layout

\end_inset

 which has hosted the project since 1999 and donates significant download bandwidth.
\emph default

\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


\emph on
Also thanks to all SDCC Distributed Compile Farm members for donating CPU cycles and bandwidth for snapshot builds.
\begin_inset Newline newline
\end_inset


\end_layout

\begin_layout Standard
This document was initially written by Sandeep Dutta and updated by SDCC developers.
\end_layout

\begin_layout Standard
All product names mentioned herein may be trademarks
\begin_inset Index idx
range none
pageformat default
status collapsed

\begin_layout Plain Layout
Trademarks
\end_layout

\end_inset

 of their respective companies.
 
\end_layout

\begin_layout Section*
Alphabetical index
\end_layout

\begin_layout Standard
To avoid confusion,
 the installation and building options for SDCC itself (chapter 2) are not part of the index.
\end_layout

\begin_layout Standard
\begin_inset CommandInset index_print
LatexCommand printindex
type "idx"
name "Index"
literal "true"

\end_inset


\end_layout

\end_body
\end_document
