/*
 * register - set or print a custom register value
 *
 * Copyright (C) 2007  Landon Curt Noll
 *
 * Calc is open software; you can redistribute it and/or modify it under
 * the terms of the version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * Calc is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General
 * Public License for more details.
 *
 * A copy of version 2.1 of the GNU Lesser General Public License is
 * distributed with calc under the filename COPYING-LGPL.  You should have
 * received a copy with calc; if not, write to Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Under source code control:   2007/07/05 11:11:11
 * File existed as early as:    2007
 *
 * chongo <was here> /\oo/\     http://www.isthe.com/chongo/
 * Share and enjoy!  :-)        http://www.isthe.com/chongo/tech/comp/calc/
 */

/*
 * This file is part of the custom sample calc files.
 *
 * NOTE: You must use a calc that was compiled with ALLOW_CUSTOM= -DCUSTOM
 *       and run with a -C arg.
 */
if (config("compile_custom") == 0) {
        quit "calc compiled without -DCUSTOM";
} else if (config("allow_custom") == 0) {
        quit "calc was run without the -D command line option";
}


define register(num)
{
        local reg_max;      /* number of registers */

        /*
         * firewall
         */
        if (!isnum(num)) {
                return newerror("register only works on numeric values");
        }

        /*
         * determine register count
         */
        reg_max = custom("sysinfo", "REGNUM_MAX");

        /*
         * determine the HALF length of a numeric value
         */
        if (num < 0) {
                return newerror("register number must be >= 0");
        } else if (num > reg_max) {
                return newerror("register number must be < REGNUM_MAX");
        } else {
                return custom("register", num);
        }
}
