//! [F16C intrinsics].
//!
//! [F16C intrinsics]: https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=fp16&expand=1769

use crate::core_arch::{simd::*, x86::*};
use crate::intrinsics::simd::*;

#[cfg(test)]
use stdarch_test::assert_instr;

#[allow(improper_ctypes)]
unsafe extern "unadjusted" {
    #[link_name = "llvm.x86.vcvtps2ph.128"]
    fn llvm_vcvtps2ph_128(a: f32x4, rounding: i32) -> i16x8;
    #[link_name = "llvm.x86.vcvtps2ph.256"]
    fn llvm_vcvtps2ph_256(a: f32x8, rounding: i32) -> i16x8;
}

/// Converts the 4 x 16-bit half-precision float values in the lowest 64-bit of
/// the 128-bit vector `a` into 4 x 32-bit float values stored in a 128-bit wide
/// vector.
///
/// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_cvtph_ps)
#[inline]
#[target_feature(enable = "f16c")]
#[cfg_attr(test, assert_instr("vcvtph2ps"))]
#[stable(feature = "x86_f16c_intrinsics", since = "1.68.0")]
#[rustc_const_unstable(feature = "stdarch_const_x86", issue = "149298")]
pub const fn _mm_cvtph_ps(a: __m128i) -> __m128 {
    unsafe {
        let a: f16x8 = transmute(a);
        let a: f16x4 = simd_shuffle!(a, a, [0, 1, 2, 3]);
        simd_cast(a)
    }
}

/// Converts the 8 x 16-bit half-precision float values in the 128-bit vector
/// `a` into 8 x 32-bit float values stored in a 256-bit wide vector.
///
/// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm256_cvtph_ps)
#[inline]
#[target_feature(enable = "f16c")]
#[cfg_attr(test, assert_instr("vcvtph2ps"))]
#[stable(feature = "x86_f16c_intrinsics", since = "1.68.0")]
#[rustc_const_unstable(feature = "stdarch_const_x86", issue = "149298")]
pub const fn _mm256_cvtph_ps(a: __m128i) -> __m256 {
    unsafe {
        let a: f16x8 = transmute(a);
        simd_cast(a)
    }
}

/// Converts the 4 x 32-bit float values in the 128-bit vector `a` into 4 x
/// 16-bit half-precision float values stored in the lowest 64-bit of a 128-bit
/// vector.
///
/// Rounding is done according to the `imm_rounding` parameter, which can be one of:
///
/// * [`_MM_FROUND_TO_NEAREST_INT`] : round to nearest
/// * [`_MM_FROUND_TO_NEG_INF`] : round down
/// * [`_MM_FROUND_TO_POS_INF`] : round up
/// * [`_MM_FROUND_TO_ZERO`] : truncate
/// * [`_MM_FROUND_CUR_DIRECTION`] : use `MXCSR.RC` - see [`_MM_SET_ROUNDING_MODE`]
///
/// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_cvtps_ph)
#[inline]
#[target_feature(enable = "f16c")]
#[cfg_attr(test, assert_instr("vcvtps2ph", IMM_ROUNDING = 0))]
#[rustc_legacy_const_generics(1)]
#[stable(feature = "x86_f16c_intrinsics", since = "1.68.0")]
pub fn _mm_cvtps_ph<const IMM_ROUNDING: i32>(a: __m128) -> __m128i {
    static_assert_round_mode!(IMM_ROUNDING);
    unsafe {
        let a = a.as_f32x4();
        let r = llvm_vcvtps2ph_128(a, IMM_ROUNDING);
        transmute(r)
    }
}

/// Converts the 8 x 32-bit float values in the 256-bit vector `a` into 8 x
/// 16-bit half-precision float values stored in a 128-bit wide vector.
///
/// Rounding is done according to the `imm_rounding` parameter, which can be one of:
///
/// * [`_MM_FROUND_TO_NEAREST_INT`] : round to nearest
/// * [`_MM_FROUND_TO_NEG_INF`] : round down
/// * [`_MM_FROUND_TO_POS_INF`] : round up
/// * [`_MM_FROUND_TO_ZERO`] : truncate
/// * [`_MM_FROUND_CUR_DIRECTION`] : use `MXCSR.RC` - see [`_MM_SET_ROUNDING_MODE`]
///
/// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm256_cvtps_ph)
#[inline]
#[target_feature(enable = "f16c")]
#[cfg_attr(test, assert_instr("vcvtps2ph", IMM_ROUNDING = 0))]
#[rustc_legacy_const_generics(1)]
#[stable(feature = "x86_f16c_intrinsics", since = "1.68.0")]
pub fn _mm256_cvtps_ph<const IMM_ROUNDING: i32>(a: __m256) -> __m128i {
    static_assert_round_mode!(IMM_ROUNDING);
    unsafe {
        let a = a.as_f32x8();
        let r = llvm_vcvtps2ph_256(a, IMM_ROUNDING);
        transmute(r)
    }
}

#[cfg(test)]
mod tests {
    use crate::core_arch::assert_eq_const as assert_eq;
    use crate::core_arch::x86::*;
    use stdarch_test::simd_test;

    const F16_ONE: i16 = 0x3c00;
    const F16_TWO: i16 = 0x4000;
    const F16_THREE: i16 = 0x4200;
    const F16_FOUR: i16 = 0x4400;
    const F16_FIVE: i16 = 0x4500;
    const F16_SIX: i16 = 0x4600;
    const F16_SEVEN: i16 = 0x4700;
    const F16_EIGHT: i16 = 0x4800;

    #[simd_test(enable = "f16c")]
    const fn test_mm_cvtph_ps() {
        let a = _mm_set_epi16(0, 0, 0, 0, F16_ONE, F16_TWO, F16_THREE, F16_FOUR);
        let r = _mm_cvtph_ps(a);
        let e = _mm_set_ps(1.0, 2.0, 3.0, 4.0);
        assert_eq_m128(r, e);
    }

    #[simd_test(enable = "f16c")]
    const fn test_mm256_cvtph_ps() {
        let a = _mm_set_epi16(
            F16_ONE, F16_TWO, F16_THREE, F16_FOUR, F16_FIVE, F16_SIX, F16_SEVEN, F16_EIGHT,
        );
        let r = _mm256_cvtph_ps(a);
        let e = _mm256_set_ps(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0);
        assert_eq_m256(r, e);
    }

    #[simd_test(enable = "f16c")]
    fn test_mm_cvtps_ph() {
        let a = _mm_set_ps(1.0, 2.0, 3.0, 4.0);
        let r = _mm_cvtps_ph::<_MM_FROUND_CUR_DIRECTION>(a);
        let e = _mm_set_epi16(0, 0, 0, 0, F16_ONE, F16_TWO, F16_THREE, F16_FOUR);
        assert_eq_m128i(r, e);
    }

    #[simd_test(enable = "f16c")]
    fn test_mm256_cvtps_ph() {
        let a = _mm256_set_ps(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0);
        let r = _mm256_cvtps_ph::<_MM_FROUND_CUR_DIRECTION>(a);
        let e = _mm_set_epi16(
            F16_ONE, F16_TWO, F16_THREE, F16_FOUR, F16_FIVE, F16_SIX, F16_SEVEN, F16_EIGHT,
        );
        assert_eq_m128i(r, e);
    }
}
