f16c.rs.html -- source
Description: Source to the Rust file `src/libcore/../stdarch/crates/core_arch/src/x86/f16c.rs`.
Keywords: rust, rustlang, rust-lang

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    //! [F16C intrinsics].
    //!
    //! [F16C intrinsics]: https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=fp16&expand=1769

    use crate::{
        core_arch::{simd::*, x86::*},
        hint::unreachable_unchecked,
        mem::transmute,
    };

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

    #[allow(improper_ctypes)]
    extern "unadjusted" {
        #[link_name = "llvm.x86.vcvtph2ps.128"]
        fn llvm_vcvtph2ps_128(a: i16x8) -> f32x4;
        #[link_name = "llvm.x86.vcvtph2ps.256"]
        fn llvm_vcvtph2ps_256(a: i16x8) -> f32x8;
        #[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.
    #[inline]
    #[target_feature(enable = "f16c")]
    #[cfg_attr(test, assert_instr("vcvtph2ps"))]
    pub unsafe fn _mm_cvtph_ps(a: __m128i) -> __m128 {
        transmute(llvm_vcvtph2ps_128(transmute(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.
    #[inline]
    #[target_feature(enable = "f16c")]
    #[cfg_attr(test, assert_instr("vcvtph2ps"))]
    pub unsafe fn _mm256_cvtph_ps(a: __m128i) -> __m256 {
        transmute(llvm_vcvtph2ps_256(transmute(a)))
    }

    macro_rules! dispatch_rounding {
        ($rounding:ident, $call:ident) => {{
            match $rounding {
                0 => call!(0),
                1 => call!(1),
                2 => call!(2),
                3 => call!(3),
                4 => call!(4),
                5 => call!(5),
                6 => call!(6),
                7 => call!(7),
                _ => unreachable_unchecked(),
            }
        }};
    }

    /// 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 | _MM_FROUND_NO_EXC`: round to nearest and suppress exceptions,
    /// * `_MM_FROUND_TO_NEG_INF | _MM_FROUND_NO_EXC`: round down and suppress exceptions,
    /// * `_MM_FROUND_TO_POS_INF | _MM_FROUND_NO_EXC`: round up and suppress exceptions,
    /// * `_MM_FROUND_TO_ZERO | _MM_FROUND_NO_EXC`: truncate and suppress exceptions,
    /// * `_MM_FROUND_CUR_DIRECTION`: use `MXCSR.RC` - see [`_MM_SET_ROUNDING_MODE`].
    #[inline]
    #[target_feature(enable = "f16c")]
    #[rustc_args_required_const(1)]
    #[cfg_attr(test, assert_instr("vcvtps2ph", imm_rounding = 0))]
    pub unsafe fn _mm_cvtps_ph(a: __m128, imm_rounding: i32) -> __m128i {
        let a = transmute(a);
        macro_rules! call {
            ($rounding:expr) => {
                llvm_vcvtps2ph_128(a, $rounding)
            };
        }
        transmute(dispatch_rounding!(imm_rounding, call))
    }

    /// 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 | _MM_FROUND_NO_EXC`: round to nearest and suppress exceptions,
    /// * `_MM_FROUND_TO_NEG_INF | _MM_FROUND_NO_EXC`: round down and suppress exceptions,
    /// * `_MM_FROUND_TO_POS_INF | _MM_FROUND_NO_EXC`: round up and suppress exceptions,
    /// * `_MM_FROUND_TO_ZERO | _MM_FROUND_NO_EXC`: truncate and suppress exceptions,
    /// * `_MM_FROUND_CUR_DIRECTION`: use `MXCSR.RC` - see [`_MM_SET_ROUNDING_MODE`].
    #[inline]
    #[target_feature(enable = "f16c")]
    #[rustc_args_required_const(1)]
    #[cfg_attr(test, assert_instr("vcvtps2ph", imm_rounding = 0))]
    pub unsafe fn _mm256_cvtps_ph(a: __m256, imm_rounding: i32) -> __m128i {
        let a = transmute(a);
        macro_rules! call {
            ($rounding:expr) => {
                llvm_vcvtps2ph_256(a, $rounding)
            };
        }
        transmute(dispatch_rounding!(imm_rounding, call))
    }

    #[cfg(test)]
    mod tests {
        use crate::{core_arch::x86::*, mem::transmute};
        use stdarch_test::simd_test;

        #[simd_test(enable = "f16c")]
        unsafe fn test_mm_cvtph_ps() {
            let array = [1_f32, 2_f32, 3_f32, 4_f32];
            let float_vec: __m128 = transmute(array);
            let halfs: __m128i = _mm_cvtps_ph(float_vec, 0);
            let floats: __m128 = _mm_cvtph_ps(halfs);
            let result: [f32; 4] = transmute(floats);
            assert_eq!(result, array);
        }

        #[simd_test(enable = "f16c")]
        unsafe fn test_mm256_cvtph_ps() {
            let array = [1_f32, 2_f32, 3_f32, 4_f32, 5_f32, 6_f32, 7_f32, 8_f32];
            let float_vec: __m256 = transmute(array);
            let halfs: __m128i = _mm256_cvtps_ph(float_vec, 0);
            let floats: __m256 = _mm256_cvtph_ps(halfs);
            let result: [f32; 8] = transmute(floats);
            assert_eq!(result, array);
        }
    }