Addition Intrinsics

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

extern __m128i _mm_hadd_epi16 (__m128i a, __m128i b);

Add horizontally packed signed words.

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

for (i = 0; i < 4; i++) {

  r[i] = a[2*i] + a[2i+1];

  r[i+4] = b[2*i] + b[2*i+1];

extern __m128i _mm_hadd_epi32 (__m128i a, __m128i b);

Add horizontally packed signed dwords.

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

for (i = 0; i < 2; i++) {

  r[i] = a[2*i] + a[2i+1];

  r[i+2] = b[2*i] + b[2*i+1];

extern __m128i _mm_hadds_epi16 (__m128i a, __m128i b);

Add horizontally packed signed words with signed saturation.

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

for (i = 0; i < 4; i++) {

  r[i] = signed_saturate_to_word(a[2*i] + a[2i+1]);

  r[i+4] = signed_saturate_to_word(b[2*i] + b[2*i+1]);

extern __m64 _mm_hadd_pi16 (__m64 a, __m64 b);

Add horizontally packed signed words.

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

for (i = 0; i < 2; i++) {

  r[i] = a[2*i] + a[2i+1];

  r[i+2] = b[2*i] + b[2*i+1];

extern __m64 _mm_hadd_pi32 (__m64 a, __m64 b);

Add horizontally packed signed dwords.

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

r[0] = a[1] + a[0];

r[1] = b[1] + b[0];

extern __m64 _mm_hadds_pi16 (__m64 a, __m64 b);

Add horizontally packed signed words with signed saturation.

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

for (i = 0; i < 2; i++) {

  r[i] = signed_saturate_to_word(a[2*i] + a[2i+1]);

  r[i+2] = signed_saturate_to_word(b[2*i] + b[2*i+1]);