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 | AVX512BW | Shift right 64 bits in k2 by immediate and write result in k1. |
| VEX.L0.66.0F3A.W0 31 /r KSHIFTRD k1, k2, imm8 | RRI | V/V | AVX512BW | Shift right 32 bits in k2 by immediate and write result in k1. |
Instruction Operand Encoding
| 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 Table 2-63, “TYPE K20 Exception Definition (VEX-Encoded OpMask Instructions w/o Memory Arg).”
This UNOFFICIAL, mechanically-separated, non-verified reference is provided for convenience, but it may be incomplete or broken in various obvious or non-obvious ways. Refer to Intel® 64 and IA-32 Architectures Software Developer’s Manual for anything serious.