Negation Intrinsics

These Supplemental Streaming SIMD Extensions 3 (SSSE3) intrinsics are used for negation. The prototypes for these intrinsics are in tmmintrin.h. You can also use the ia32intrin.h header file for these intrinsics.

_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];
 }
}