PSHUFLW—Shuffle Packed Low Words

INSTRUCTION SET REFERENCE, M-U

4-424 Vol. 2B

EVEX encoded version: The destination operand is a ZMM/YMM/XMM registers. The source operand can be a 
ZMM/YMM/XMM register, a 512/256/128-bit memory location. The destination is updated according to the 
writemask.
Note: In VEX encoded versions, VEX.vvvv is reserved and must be 1111b otherwise instructions will #UD.

Operation

PSHUFLW (128-bit Legacy SSE version)
DEST[15:0]  (SRC >> (imm[1:0] *16))[15:0]
DEST[31:16]  (SRC >> (imm[3:2] * 16))[15:0]
DEST[47:32]  (SRC >> (imm[5:4] * 16))[15:0]
DEST[63:48]  (SRC >> (imm[7:6] * 16))[15:0]
DEST[127:64]  SRC[127:64]
DEST[VLMAX-1:128] (Unmodified)

VPSHUFLW (VEX.128 encoded version)
DEST[15:0]  (SRC1 >> (imm[1:0] *16))[15:0]
DEST[31:16]  (SRC1 >> (imm[3:2] * 16))[15:0]
DEST[47:32]  (SRC1 >> (imm[5:4] * 16))[15:0]
DEST[63:48]  (SRC1 >> (imm[7:6] * 16))[15:0]
DEST[127:64]  SRC[127:64]
DEST[VLMAX-1:128]  0

VPSHUFLW (VEX.256 encoded version)
DEST[15:0]  (SRC1 >> (imm[1:0] *16))[15:0]
DEST[31:16]  (SRC1 >> (imm[3:2] * 16))[15:0]
DEST[47:32]  (SRC1 >> (imm[5:4] * 16))[15:0]
DEST[63:48]  (SRC1 >> (imm[7:6] * 16))[15:0]
DEST[127:64]  SRC1[127:64]
DEST[143:128]  (SRC1 >> (imm[1:0] *16))[143:128]
DEST[159:144]  (SRC1 >> (imm[3:2] * 16))[143:128]
DEST[175:160]  (SRC1 >> (imm[5:4] * 16))[143:128]
DEST[191:176]  (SRC1 >> (imm[7:6] * 16))[143:128]
DEST[255:192]  SRC1[255:192]
DEST[VLMAX-1:256]  0

VPSHUFLW (EVEX.U1.512 encoded version)
(KL, VL) = (8, 128), (16, 256), (32, 512)
IF VL >= 128

TMP_DEST[15:0]  (SRC1 >> (imm[1:0] *16))[15:0]
TMP_DEST[31:16]  (SRC1 >> (imm[3:2] * 16))[15:0]
TMP_DEST[47:32]  (SRC1 >> (imm[5:4] * 16))[15:0]
TMP_DEST[63:48]  (SRC1 >> (imm[7:6] * 16))[15:0]
TMP_DEST[127:64]  SRC1[127:64]

FI;
IF VL >= 256

TMP_DEST[143:128]  (SRC1 >> (imm[1:0] *16))[143:128]
TMP_DEST[159:144]  (SRC1 >> (imm[3:2] * 16))[143:128]
TMP_DEST[175:160]  (SRC1 >> (imm[5:4] * 16))[143:128]
TMP_DEST[191:176]  (SRC1 >> (imm[7:6] * 16))[143:128]
TMP_DEST[255:192]  SRC1[255:192]

FI;
IF VL >= 512

TMP_DEST[271:256]  (SRC1 >> (imm[1:0] *16))[271:256]
TMP_DEST[287:272]  (SRC1 >> (imm[3:2] * 16))[271:256]