PMAXUW — Maximum of Packed Word Integers

Opcode/Instruction Op/En 64/32 bit Mode Support CPUID Feature Flag Description
66 0F 38 3E /r PMAXUW xmm1, xmm2/m128 RM V/V SSE4_1 Compare packed unsigned word integers in xmm1 and xmm2/m128 and store packed maximum values in xmm1.
VEX.NDS.128.66.0F38.WIG 3E/r VPMAXUW xmm1, xmm2, xmm3/m128 RVM V/V AVX Compare packed unsigned word integers in xmm3/m128 and xmm2 and store maximum packed values in xmm1.
VEX.NDS.256.66.0F38.WIG 3E /r VPMAXUW ymm1, ymm2, ymm3/m256 RVM V/V AVX2 Compare packed unsigned word integers in ymm3/m256 and ymm2 and store maximum packed values in ymm1.

Instruction Operand Encoding

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

Description

Compares packed unsigned word integers in the destination operand (first operand) and the source operand (second operand), and returns the maximum for each packed value in the destination operand.

128-bit Legacy SSE version: The first source and destination operands are XMM registers. The second source operand is an XMM register or a 128-bit memory location. Bits (VLMAX-1:128) of the corresponding YMM destina-tion register remain unchanged.

VEX.128 encoded version: The first source and destination operands are XMM registers. The second source operand is an XMM register or a 128-bit memory location. Bits (VLMAX-1:128) of the destination YMM register are zeroed.

VEX.256 encoded version: The second source operand can be an YMM register or a 256-bit memory location. The first source and destination operands are YMM registers.

Note: VEX.L must be 0, otherwise the instruction will #UD.

Operation

IF (DEST[15:0] > SRC[15:0])
    THEN DEST[15:0] ← DEST[15:0];
    ELSE DEST[15:0] ← SRC[15:0]; FI;
IF (DEST[31:16] > SRC[31:16])
    THEN DEST[31:16] ← DEST[31:16];
    ELSE DEST[31:16] ← SRC[31:16]; FI;
IF (DEST[47:32] > SRC[47:32])
    THEN DEST[47:32] ← DEST[47:32];
    ELSE DEST[47:32] ← SRC[47:32]; FI;
IF (DEST[63:48] > SRC[63:48])
    THEN DEST[63:48] ← DEST[63:48];
    ELSE DEST[63:48] ← SRC[63:48]; FI;
IF (DEST[79:64] > SRC[79:64])
    THEN DEST[79:64] ← DEST[79:64];
    ELSE DEST[79:64] ← SRC[79:64]; FI;
IF (DEST[95:80] > SRC[95:80])
    THEN DEST[95:80] ← DEST[95:80];
    ELSE DEST[95:80] ← SRC[95:80]; FI;
IF (DEST[111:96] > SRC[111:96])
    THEN DEST[111:96] ← DEST[111:96];
    ELSE DEST[111:96] ← SRC[111:96]; FI;
IF (DEST[127:112] > SRC[127:112])
    THEN DEST[127:112] ← DEST[127:112];
    ELSE DEST[127:112] ← SRC[127:112]; FI;

VPMAXUW (VEX.128 encoded version)

    IF SRC1[15:0] > SRC2[15:0] THEN
         DEST[15:0] ← SRC1[15:0];
    ELSE
         DEST[15:0] ← SRC2[15:0]; FI;
    (* Repeat operation for 2nd through 7th words in source and destination operands *)
    IF SRC1[127:112] >SRC2[127:112] THEN
         DEST[127:112] ← SRC1[127:112];
    ELSE
         DEST[127:112] ← SRC2[127:112]; FI;
DEST[VLMAX-1:128] ← 0

VPMAXUW (VEX.256 encoded version)

    IF SRC1[15:0] > SRC2[15:0] THEN
         DEST[15:0] ← SRC1[15:0];
    ELSE
         DEST[15:0] ← SRC2[15:0]; FI;
    (* Repeat operation for 2nd through 15th words in source and destination operands *)
    IF SRC1[255:240] >SRC2[255:240] THEN
         DEST[255:240] ← SRC1[255:240];
    ELSE
         DEST[255:240] ← SRC2[255:240]; FI;

Intel C/C++ Compiler Intrinsic Equivalent

(V)PMAXUW:

__m128i _mm_max_epu16 ( __m128i a, __m128i b);

VPMAXUW:

__m256i _mm256_max_epu16 ( __m256i a, __m256i b)

Flags Affected

None.

SIMD Floating-Point Exceptions

None.

Other Exceptions

See Exceptions Type 4; additionally

#UD If VEX.L = 1.