These Intel® Supplemental Streaming SIMD Extensions 3 (Intel® 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.
extern __m128i _mm_sign_epi8 (__m128i a, __m128i b);
Negate 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];
}
}
extern __m128i _mm_sign_epi16 (__m128i a, __m128i b);
Negate 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];
}
}
extern __m128i _mm_sign_epi32 (__m128i a, __m128i b);
Negate packed dwords 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];
}
}
extern __m64 _mm_sign_pi8 (__m64 a, __m64 b);
Negate 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];
}
}
extern __m64 _mm_sign_pi16 (__m64 a, __m64 b);
Negate 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];
}
}
extern __m64 _mm_sign_pi32 (__m64 a, __m64 b);
Negate packed dwords 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];
}
}
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