Developer Guide and Reference

Contents

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; }

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804