Visible to Intel only — GUID: GUID-59BDA23C-4226-4D77-A712-2E51207DC6B2
Visible to Intel only — GUID: GUID-59BDA23C-4226-4D77-A712-2E51207DC6B2
Multiplication Intrinsics
These Supplemental Streaming SIMD Extensions 3 (SSSE3) intrinsics are used for multiplication. The prototypes for these intrinsics are in tmmintrin.h.
To use these intrinsics, include the immintrin.h file as follows:
#include <immintrin.h>
_mm_maddubs_epi16
extern __m128i _mm_maddubs_epi16(__m128i a, __m128i b);
Multiplies signed and unsigned bytes, adds horizontal pair of signed words, and packs saturated signed words.
Interpreting a as array of unsigned 8-bit integers, b as arrays of signed 8-bit integers, and r as arrays of 16-bit signed integers:
for (i = 0; i < 8; i++) { r[i] = signed_saturate_to_word(a[2*i+1] * b[2*i+1] + a[2*i]*b[2*i]); }
_mm_maddubs_pi16
extern __m64 _mm_maddubs_pi16(__m64 a, __m64 b);
Multiplies signed and unsigned bytes, adds horizontal pair of signed words, and packs saturated signed words.
Interpreting a as array of unsigned 8-bit integers, b as arrays of signed 8-bit integers, and r as arrays of 16-bit signed integers:
for (i = 0; i < 4; i++) { r[i] = signed_saturate_to_word(a[2*i+1] * b[2*i+1] + a[2*i]*b[2*i]); }
_mm_mulhrs_epi16
extern __m128i _mm_mulhrs_epi16(__m128i a, __m128i b);
Multiplies signed words, scales and rounds signed doublewords, and packs high 16-bits.
Interpreting a, b, and r as arrays of signed 16-bit integers:
for (i = 0; i < 8; i++) { r[i] = (( (int32)((a[i] * b[i]) >> 14) + 1) >> 1) & 0xFFFF; }
_mm_mulhrs_pi16
extern __m64 _mm_mulhrs_pi16(__m64 a, __m64 b);
Multiplies signed words, scales and rounds signed doublewords, and packs high 16-bits.
Interpreting a, b, and r as arrays of signed 16-bit integers:
for (i = 0; i < 4; i++) { r[i] = (( (int32)((a[i] * b[i]) >> 14) + 1) >> 1) & 0xFFFF; }