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Microsoft Specific

Emits the Supplemental Streaming SIMD Extensions 3 (SSSE3) instruction phaddw. This instruction adds the elements of two 64-bit parameters.

__m64 _mm_hadd_pi16( 
   __m64 a,
   __m64 b

[in] a

A 64-bit parameter that contains four 16-bit signed integers.

[in] b

A 64-bit parameter that contains four 16-bit signed integers.

A 64-bit value that contains four 16-bit signed integers. Each integer is the sum between adjacent pairs of elements in the input parameters.

The result can be expressed with the following equations:

r0 := a0 + a1
r1 := a2 + a3
r2 := b0 + b1
r3 := b2 + b3




x86, x64

Header file <tmmintrin.h>

r0-r3, a0-a3, and b0-b3 are the sequentially ordered 16-bit components of return value r and parameters a and b. r0, a0, and b0 are the least significant 16 bits.

Before you use this intrinsic, software must ensure that the underlying processor supports the instruction.

#include <stdio.h>
#include <tmmintrin.h>

int main ()
    __m64 a, b;

    a.m64_i16[0] = -1;
    a.m64_i16[1] = 1;
    a.m64_i16[2] = 4096;
    a.m64_i16[3] = 127;
    b.m64_i16[0] = -127;
    b.m64_i16[1] = 50;
    b.m64_i16[2] = 64;
    b.m64_i16[3] = -128;

    __m64 res = _mm_hadd_pi16(a, b);

    printf_s("Original a:\t%4d\t%4d\t%4d\t%4d\nOriginal b:\t%4d\t%4d\t%4d\t%4d\n",
                a.m64_i16[0], a.m64_i16[1], a.m64_i16[2], a.m64_i16[3],
                b.m64_i16[0], b.m64_i16[1], b.m64_i16[2], b.m64_i16[3]);
    printf_s("Result res:\t%4d\t%4d\t%4d\t%4d\n",
                res.m64_i16[0], res.m64_i16[1], res.m64_i16[2], res.m64_i16[3]);


    return 0;
Original a:       -1       1    4096     127
Original b:     -127      50      64    -128
Result res:        0    4223     -77     -64