KSHIFTRW_KSHIFTRB_KSHIFTRQ_KSHIFTRD

KSHIFTRW / KSHIFTRB / KSHIFTRQ / KSHIFTRD

Intel Architecture Software Developer's Manual (July 2017)

KSHIFTRW / KSHIFTRB / KSHIFTRQ / KSHIFTRD - Shift Right Mask Registers

Opcode/ Instruction	Op/En	64/32 bit Mode Support	CPUID Feature Flag	Description
VEX.L0.66.0F3A.W1 30 /r KSHIFTRW k1, k2, imm8	RRI	V/V	AVX512F	Shift right 16 bits in k2 by immediate and write result in k1.
VEX.L0.66.0F3A.W0 30 /r KSHIFTRB k1, k2, imm8	RRI	V/V	AVX512DQ	Shift right 8 bits in k2 by immediate and write result in k1.
VEX.L0.66.0F3A.W1 31 /r KSHIFTRQ k1, k2, imm8	RRI	V/V
VEX.L0.66.0F3A.W0 31 /r KSHIFTRD k1, k2, imm8	RRI	V/V

Op/En	Operand 1	Operand 2	Operand 3
RRI	ModRM:reg (w)	ModRM:r/m (r, ModRM:[7:6] must be 11b)	Imm8

Description

Shifts 8/16/32/64 bits in the second operand (source operand) right by the count specified in immediate and place the least significant 8/16/32/64 bits of the result in the destination operand. The higher bits of the destination are zero-extended. The destination is set to zero if the count value is greater than 7 (for byte shift), 15 (for word shift), 31 (for doubleword shift) or 63 (for quadword shift).

Operation

KSHIFTRW
COUNT ← imm8[7:0]
DEST[MAX_KL-1:0] ← 0
IF COUNT <=15
    THEN DEST[15:0] ← SRC1[15:0] >> COUNT;
FI;
KSHIFTRB
COUNT ← imm8[7:0]
DEST[MAX_KL-1:0] ← 0
IF COUNT <=7
        THEN
            DEST[7:0] ← SRC1[7:0] >> COUNT;
FI;
KSHIFTRQ
COUNT ← imm8[7:0]
DEST[MAX_KL-1:0] ← 0
IF COUNT <=63
        THEN
            DEST[63:0] ← SRC1[63:0] >> COUNT;
FI;
KSHIFTRD
COUNT ← imm8[7:0]
DEST[MAX_KL-1:0] ← 0
IF COUNT <=31
        THEN
            DEST[31:0] ← SRC1[31:0] >> COUNT;
FI;

Intel C/C++ Compiler Intrinsic Equivalent

Compiler auto generates KSHIFTRW when needed.

Flags Affected

None

SIMD Floating-Point Exceptions

None

Other Exceptions

See Exceptions Type K20.