# Negation Intrinsics

These Supplemental Streaming SIMD Extensions 3 (SSSE3) intrinsics are used for negation. The prototypes for these intrinsics are in tmmintrin.h.

To use these intrinsics, include the immintrin.h file as follows:

    #include <immintrin.h>

## _mm_sign_epi8

extern __m128i _mm_sign_epi8(__m128i a, __m128i b);

Negates packed bytes in a if corresponding sign in b is less than zero.

Interpreting a, b, and r as arrays of signed 8-bit integers:

    for (i = 0; i < 16; i++){
     if (b[i] < 0){
      r[i] =  -a[i];
     }
     else
     if (b[i] == 0){
      r[i] = 0;
     }
     else {
      r[i] = a[i];
     }
    }

## _mm_sign_epi16

extern __m128i _mm_sign_epi16(__m128i a, __m128i b);

Negates packed words in a if corresponding sign in b is less than zero.

Interpreting a, b, and r as arrays of signed 16-bit integers:

    for (i = 0; i < 8; i++){
     if (b[i] < 0){
      r[i] =  -a[i];
     }
    else
     if (b[i] == 0){
      r[i] = 0;
     }
     else
     {
      r[i] = a[i];
     }
    }

## _mm_sign_epi32

extern __m128i _mm_sign_epi32(__m128i a, __m128i b);

Negates packed doublewords in a if corresponding sign in b is less than zero.

Interpreting a, b, and r as arrays of signed 32-bit integers:

    for (i = 0; i < 4; i++){
     if (b[i] < 0){
      r[i] = -a[i];
     }
     else
     if (b[i] == 0){
      r[i] = 0;
     }
     else {
      r[i] = a[i];
     }
    }

## _mm_sign_pi8

extern __m64 _mm_sign_pi8(__m64 a, __m64 b);

Negates packed bytes in a if corresponding sign in b is less than zero.

Interpreting a, b, and r as arrays of signed 8-bit integers:

    for (i = 0; i < 16; i++){
     if (b[i] < 0){
      r[i] =  -a[i];
     }
     else
     if (b[i] == 0){
      r[i] = 0;
     }
     else {
      r[i] = a[i];
     }
    }

## _mm_sign_pi16

extern __m64 _mm_sign_pi16(__m64 a, __m64 b);

Negates packed words in a if corresponding sign in b is less than zero.

Interpreting a, b, and r as arrays of signed 16-bit integers:

    for (i = 0; i < 8; i++){
     if (b[i] < 0){
      r[i] =  -a[i];
      }
     else
     if (b[i] == 0){
      r[i] = 0;
      }
     else {
      r[i] = a[i];
      }
    }

## _mm_sign_pi32

extern __m64 _mm_sign_pi32(__m64 a, __m64 b);

Negates packed doublewords in a if corresponding sign in b is less than zero.

Interpreting a, b, and r as arrays of signed 32-bit integers:

    for (i = 0; i < 2; i++){
     if (b[i] < 0){
      r[i] =  -a[i];
     }
     else
     if (b[i] == 0){
      r[i] = 0;
     }
     else {
      r[i] = a[i];
     }
    }

Parent topic: Intrinsics for Intel® Supplemental Streaming SIMD Extensions 3 (SSSE3)