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_mm_nmsub_sd

Visual Studio 2010 SP1 is required.

Microsoft Specific

Generates the FMA4 XMM instruction vfnmsubsd to perform a single-round double-precision floating-point negative multiply-subtract of the low-order floating-point values of its sources.

__m128d _mm_nmsub_sd (
   __m128d src1,
   __m128d src2,
   __m128d src3
);

Parameters

  • [in] src1
    A 128-bit parameter that contains a 64-bit floating-point value in the low quadword.

  • [in] src2
    A 128-bit parameter that contains a 64-bit floating-point value in the low quadword.

  • [in] src3
    A 128-bit parameter that contains a 64-bit floating-point value in the low quadword.

Return value

A 128-bit result r that contains two 64-bit floating-point values.

r[0] := -(src1[0] * src2[0]) - src3[0];
r[1] := 0.;

Requirements

Intrinsic

Architecture

_mm_nmsub_sd

FMA4

Header file <intrin.h>

Remarks

The low-order double-precision floating-point value in src1 is multiplied by the corresponding value in src2. The result is negated, the corresponding value in src3 is subtracted from it, and the result is stored as the corresponding value in the destination. The other values in src1, src2, and src3 are ignored, and the high-order double-precision floating-point value of the result is set to 0. The multiply-negate-subtract is performed with a single round at the end, as if intermediate results were computed to infinite precision.

The vfnmsubsd instruction is part of the FMA4 family of instructions. Before you use this intrinsic, you must ensure that the processor supports this instruction. To determine hardware support for this instruction, call the __cpuid intrinsic with InfoType = 0x80000001 and check bit 16 of CPUInfo[2] (ECX). This bit is 1 when the instruction is supported, and 0 otherwise.

Example

#include <stdio.h>
#include <intrin.h>
int main()
{
    __m128d a, b, c, d;
    int i;
    for (i = 0; i < 2; i++) {
        a.m128d_f64[i] = i;
        b.m128d_f64[i] = 2.;
        c.m128d_f64[i] = 3.;
    }
    d = _mm_nmsub_sd(a, b, c);
    for (i = 0; i < 2; i++) printf_s(" %.3lf", d.m128d_f64[i]);
    printf_s("\n");
}
-3.000 0.000

See Also

Reference

_mm256_nmsub_pd

_mm_nmsub_pd

_mm_nmsub_ss

_mm_macc_sd

_mm_nmacc_sd

_mm_msub_sd

__cpuid, __cpuidex

FMA4 Intrinsics Added for Visual Studio 2010 SP1