PDEP—Parallel Bits Deposit

Opcode/Instruction Op/En 64/32-bit Mode CPUID Feature Flag Description
VEX.LZ.F2.0F38.W0 F5 /r PDEP r32a, r32b, r/m32 RVM V/V BMI2 Parallel deposit of bits from r32b using mask in r/m32, result is written to r32a.
VEX.LZ.F2.0F38.W1 F5 /r PDEP r64a, r64b, r/m64 RVM V/N.E. BMI2 Parallel deposit of bits from r64b using mask in r/m64, result is written to r64a.

Instruction Operand Encoding

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

Description

PDEP uses a mask in the second source operand (the third operand) to transfer/scatter contiguous low order bits in the first source operand (the second operand) into the destination (the first operand). PDEP takes the low bits from the first source operand and deposit them in the destination operand at the corresponding bit locations that are set in the second source operand (mask). All other bits (bits not set in mask) in destination are set to zero.

SRC1

S7 S6 S5 S4 S3 S2 S0

S1

SRC2

0

0

0

1

0

1

0

1

0

0

1

0

0

S2 0 S1 0 0 S0 0 0 0 0 0 S3 0

(mask)

DEST

bit 0

bit 31

Figure 4-8. PDEP Example

This instruction is not supported in real mode and virtual-8086 mode. The operand size is always 32 bits if not in 64-bit mode. In 64-bit mode operand size 64 requires VEX.W1. VEX.W1 is ignored in non-64-bit modes. An attempt to execute this instruction with VEX.L not equal to 0 will cause #UD.

Operation

TEMP := SRC1;
MASK := SRC2;
DEST := 0 ;
m := 0, k := 0;
DO WHILE m < OperandSize
         IF MASK[ m] = 1 THEN
              DEST[ m] := TEMP[ k];
              k := k+ 1;
         FI
         m := m+ 1;
OD

Flags Affected

None.

Intel C/C++ Compiler Intrinsic Equivalent

PDEP unsigned __int32 _pdep_u32(unsigned __int32 src, unsigned __int32 mask);

PDEP unsigned __int64 _pdep_u64(unsigned __int64 src, unsigned __int32 mask);

SIMD Floating-Point Exceptions

None.

Other Exceptions

See Table 2-29, “Type 13 Class Exception Conditions.”