EXTRACTPS — Extract Packed Single Precision Floating-Point Value

Opcode/Instruction Op/En 64/32-bit Mode CPUID Feature Flag Description

66 0F 3A 17

/r ib

EXTRACTPS reg/m32, xmm2, imm8

 MRI V/V SSE4_1 Extract a single-precision floating-point value from xmm2 at the source offset specified by imm8 and store the result to reg or m32. The upper 32 bits of r64 is zeroed if reg is r64.

VEX.128.66.0F3A.WIG 17 /r ib

VEXTRACTPS r/m32, xmm1, imm8

 MRI V/V AVX Extract one single-precision floating-point value from xmm1 at the offset specified by imm8 and store the result in reg or m32. Zero extend the results in 64-bit register if applicable.

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4
MRI ModRM:r/m (w) ModRM:reg (r) imm8 NA

Description

Extracts a single-precision floating-point value from the source operand (second operand) at the 32-bit offset spec-ified from imm8. Immediate bits higher than the most significant offset for the vector length are ignored.

The extracted single-precision floating-point value is stored in the low 32-bits of the destination operand

In 64-bit mode, destination register operand has default operand size of 64 bits. The upper 32-bits of the register are filled with zero. REX.W is ignored.

128-bit Legacy SSE version: When a REX.W prefix is used in 64-bit mode with a general purpose register (GPR) as a destination operand, the packed single quantity is zero extended to 64 bits.

VEX.128 encoded version: When VEX.128.66.0F3A.W1 17 form is used in 64-bit mode with a general purpose register (GPR) as a destination operand, the packed single quantity is zero extended to 64 bits. VEX.vvvv is reserved and must be 1111b otherwise instructions will #UD.

The source register is an XMM register. Imm8[1:0] determine the starting DWORD offset from which to extract the 32-bit floating-point value.

If VEXTRACTPS is encoded with VEX.L= 1, an attempt to execute the instruction encoded with VEX.L= 1 will cause an #UD exception.

Operation

EXTRACTPS (128-bit Legacy SSE version)

SRC_OFFSET ← IMM8[1:0]
IF ( 64-Bit Mode and DEST is register)
    DEST[31:0] ← (SRC[127:0] » (SRC_OFFET*32)) AND 0FFFFFFFFh
    DEST[63:32] ← 0
ELSE
    DEST[31:0] ← (SRC[127:0] » (SRC_OFFET*32)) AND 0FFFFFFFFh
FI

VEXTRACTPS (VEX.128 encoded version)

SRC_OFFSET ← IMM8[1:0]
IF ( 64-Bit Mode and DEST is register)
    DEST[31:0] ← (SRC[127:0] » (SRC_OFFET*32)) AND 0FFFFFFFFh
    DEST[63:32] ← 0
ELSE
    DEST[31:0] ← (SRC[127:0] » (SRC_OFFET*32)) AND 0FFFFFFFFh
FI

Intel C/C++ Compiler Intrinsic Equivalent

EXTRACTPS:

_mm_extractmem_ps (float *dest, __m128 a, const int nidx);

EXTRACTPS:

__m128 _mm_extract_ps (__m128 a, const int nidx);

SIMD Floating-Point Exceptions

None

Other Exceptions

See Exceptions Type 5; additionally

#UD If VEX.L= 1.