PSRAW/PSRAD—Shift Packed Data Right Arithmetic

Opcode/Instruction Op/En 64/32 bit Mode Support CPUID Feature Flag Description
0F E1 /r1 PSRAW mm, mm/m64 RM V/V MMX Shift words in mm right by mm/m64 while shifting in sign bits.
66 0F E1 /r PSRAW xmm1, xmm2/m128 RM V/V SSE2 Shift words in xmm1 right by xmm2/m128 while shifting in sign bits.
0F 71 /4 ib1 PSRAW mm, imm8 MI V/V MMX Shift words in mm right by imm8 while shifting in sign bits
66 0F 71 /4 ib PSRAW xmm1, imm8 MI V/V SSE2 Shift words in xmm1 right by imm8 while shifting in sign bits
0F E2 /r1 PSRAD mm, mm/m64 RM V/V MMX Shift doublewords in mm right by mm/m64 while shifting in sign bits.
66 0F E2 /r PSRAD xmm1, xmm2/m128 RM V/V SSE2 Shift doubleword in xmm1 right by xmm2 /m128 while shifting in sign bits.
0F 72 /4 ib1 PSRAD mm, imm8 MI V/V MMX Shift doublewords in mm right by imm8 while shifting in sign bits.
66 0F 72 /4 ib PSRAD xmm1, imm8 MI V/V SSE2 Shift doublewords in xmm1 right by imm8 while shifting in sign bits.
VEX.NDS.128.66.0F.WIG E1 /r VPSRAW xmm1, xmm2, xmm3/m128 RVM V/V AVX Shift words in xmm2 right by amount specified in xmm3/m128 while shifting in sign bits.
VEX.NDD.128.66.0F.WIG 71 /4 ib VPSRAW xmm1, xmm2, imm8 VMI V/V AVX Shift words in xmm2 right by imm8 while shifting in sign bits.
VEX.NDS.128.66.0F.WIG E2 /r VPSRAD xmm1, xmm2, xmm3/m128 RVM V/V AVX Shift doublewords in xmm2 right by amount specified in xmm3/m128 while shifting in sign bits.
VEX.NDD.128.66.0F.WIG 72 /4 ib VPSRAD xmm1, xmm2, imm8 VMI V/V AVX Shift doublewords in xmm2 right by imm8 while shifting in sign bits.
VEX.NDS.256.66.0F.WIG E1 /r VPSRAW ymm1, ymm2, xmm3/m128 RVM V/V AVX2 Shift words in ymm2 right by amount specified in xmm3/m128 while shifting in sign bits.
VEX.NDD.256.66.0F.WIG 71 /4 ib VPSRAW ymm1, ymm2, imm8 VMI V/V AVX2 Shift words in ymm2 right by imm8 while shifting in sign bits.
VEX.NDS.256.66.0F.WIG E2 /r VPSRAD ymm1, ymm2, xmm3/m128 RVM V/V AVX2 Shift doublewords in ymm2 right by amount specified in xmm3/m128 while shifting in sign bits.
VEX.NDD.256.66.0F.WIG 72 /4 ib VPSRAD ymm1, ymm2, imm8 VMI V/V AVX2 Shift doublewords in ymm2 right by imm8 while shifting in sign bits.

Notes: 1. See note in Section 2.4, “Instruction Exception Specification” in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 2A and Section 22.25.3, “Exception Conditions of Legacy SIMD Instructions Operating on MMX Registers” in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 3A.

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4
RM ModRM:reg (r, w) ModRM:r/m (r) NA NA
MI ModRM:r/m (r, w) imm8 NA NA
RVM ModRM:reg (w) VEX.vvvv (r) ModRM:r/m (r) NA
VMI VEX.vvvv (w) ModRM:r/m (r) imm8 NA

Description

Shifts the bits in the individual data elements (words or doublewords) in the destination operand (first operand) to the right by the number of bits specified in the count operand (second operand). As the bits in the data elements are shifted right, the empty high-order bits are filled with the initial value of the sign bit of the data element. If the value specified by the count operand is greater than 15 (for words) or 31 (for doublewords), each destination data element is filled with the initial value of the sign bit of the element. (Figure 4-14 gives an example of shifting words in a 64-bit operand.)

Pre-Shift

X3 PSRAW and PSRAD Instruction Operation Using a 64-bit Operand X2 X2 >> COUNT X1 X1 >> COUNT X0 DEST Shift Right with Sign Extension X0 >> COUNT DEST Figure 4-14.

Note that only the first 64-bits of a 128-bit count operand are checked to compute the count. If the second source operand is a memory address, 128 bits are loaded.

The (V)PSRAW instruction shifts each of the words in the destination operand to the right by the number of bits specified in the count operand, and the (V)PSRAD instruction shifts each of the doublewords in the destination operand.

In 64-bit mode, using a REX prefix in the form of REX.R permits this instruction to access additional registers (XMM8-XMM15).

Legacy SSE instructions: The destination operand is an MMX technology register; the count operand can be either an MMX technology register or an 64-bit memory location. 128-bit Legacy SSE version: The destination and first source operands are XMM registers. Bits (VLMAX-1:128) of the corresponding YMM destination register remain unchanged. The count operand can be either an XMM register or a 128-bit memory location or an 8-bit immediate. If the count operand is a memory address, 128 bits are loaded but the upper 64 bits are ignored. VEX.128 encoded version: The destination and first source operands are XMM registers. Bits (VLMAX-1:128) of the destination YMM register are zeroed. The count operand can be either an XMM register or a 128-bit memory location or an 8-bit immediate. If the count operand is a memory address, 128 bits are loaded but the upper 64 bits are ignored. VEX.256 encoded version: The destination and first source operands are YMM registers. The count operand can be either an XMM register or a 128-bit memory location or an 8-bit immediate.

Note: For shifts with an immediate count (VEX.128.66.0F 71-73 /4), VEX.vvvv encodes the destination register, and VEX.B + ModRM.r/m encodes the source register. VEX.L must be 0, otherwise instructions will #UD.

Operation

PSRAW (with 64-bit operand)
  IF (COUNT > 15)
     THEN COUNT ← 16;
  FI;
  DEST[15:0] ← SignExtend(DEST[15:0] >> COUNT);
  (* Repeat shift operation for 2nd and 3rd words *)
  DEST[63:48] ← SignExtend(DEST[63:48] >> COUNT);
PSRAD (with 64-bit operand)
  IF (COUNT > 31)
     THEN COUNT ← 32;
  FI;
  DEST[31:0] ← SignExtend(DEST[31:0] >> COUNT);
  DEST[63:32] ← SignExtend(DEST[63:32] >> COUNT);
PSRAW (with 128-bit operand)
  COUNT ← COUNT_SOURCE[63:0];
  IF (COUNT > 15)
     THEN COUNT ← 16;
  FI;
  DEST[15:0]
  (* Repeat shift operation for 2nd through 7th words *)
  DEST[127:112] ← SignExtend(DEST[127:112] >> COUNT);
PSRAD (with 128-bit operand)
  COUNT ← COUNT_SOURCE[63:0];
  IF (COUNT > 31)
     THEN COUNT ← 32;
  FI;
  DEST[31:0]
  (* Repeat shift operation for 2nd and 3rd doublewords *)
  DEST[127:96] ← SignExtend(DEST[127:96] >>COUNT);
PSRAW (xmm, xmm, xmm/m128)
DEST[127:0] ← ARITHMETIC_RIGHT_SHIFT_WORDS(DEST, SRC)
DEST[VLMAX-1:128] (Unmodified)
PSRAW (xmm, imm8)
DEST[127:0] ← ARITHMETIC_RIGHT_SHIFT_WORDS(DEST, imm8)
DEST[VLMAX-1:128] (Unmodified)
VPSRAW (xmm, xmm, xmm/m128)
DEST[127:0] ← ARITHMETIC_RIGHT_SHIFT_WORDS(SRC1, SRC2)
DEST[VLMAX-1:128] ← 0
VPSRAW (xmm, imm8)
DEST[127:0] ← ARITHMETIC_RIGHT_SHIFT_WORDS(SRC1, imm8)
DEST[VLMAX-1:128] ← 0
PSRAD (xmm, xmm, xmm/m128)
DEST[127:0] ← ARITHMETIC_RIGHT_SHIFT_DWORDS(DEST, SRC)
DEST[VLMAX-1:128] (Unmodified)
PSRAD (xmm, imm8)
DEST[127:0] ← ARITHMETIC_RIGHT_SHIFT_DWORDS(DEST, imm8)
DEST[VLMAX-1:128] (Unmodified)
VPSRAD (xmm, xmm, xmm/m128)
DEST[127:0] ← ARITHMETIC_RIGHT_SHIFT_DWORDS(SRC1, SRC2)
DEST[VLMAX-1:128] ← 0
VPSRAD (xmm, imm8)
DEST[127:0] ← ARITHMETIC_RIGHT_SHIFT_DWORDS(SRC1, imm8)
DEST[VLMAX-1:128] ← 0
VPSRAW (ymm, ymm, xmm/m128)
DEST[255:0] ← ARITHMETIC_RIGHT_SHIFT_WORDS_256b(SRC1, SRC2)
VPSRAW (ymm, imm8)
DEST[255:0] ← ARITHMETIC_RIGHT_SHIFT_WORDS_256b(SRC1, imm8)
VPSRAD (ymm, ymm, xmm/m128)
DEST[255:0] ← ARITHMETIC_RIGHT_SHIFT_DWORDS_256b(SRC1, SRC2)
VPSRAD (ymm, imm8)
DEST[255:0] ← ARITHMETIC_RIGHT_SHIFT_DWORDS_256b(SRC1, imm8)

Intel C/C++ Compiler Intrinsic Equivalents

PSRAW: __m64 _mm_srai_pi16 (__m64 m, int count)
PSRAW: __m64 _mm_sra_pi16 (__m64 m, __m64 count)
(V)PSRAW: count)
(V)PSRAW: __m128i _mm_sra_epi16(__m128i m, __m128i count)
VPSRAW: __m256i _mm256_srai_epi16 (__m256i m, int count)
VPSRAW: __m256i _mm256_sra_epi16 (__m256i m, __m128i count)
PSRAD: __m64 _mm_srai_pi32 (__m64 m, int count)
PSRAD: __m64 _mm_sra_pi32 (__m64 m, __m64 count)
(V)PSRAD: count)
(V)PSRAD: __m128i _mm_sra_epi32 (__m128i m, __m128i count)
VPSRAD: __m256i _mm256_srai_epi32 (__m256i m, int count)
VPSRAD: __m256i _mm256_sra_epi32 (__m256i m, __m128i count)

Flags Affected

None.

Numeric Exceptions

None.

Other Exceptions

See Exceptions Type 4 and 7 for non-VEX-encoded instructions; additionally

#UD If VEX.L = 1.