EXTRACTPS—Extract Packed Floating-Point Values

Instruction Operand Encoding

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.

VEX.128 and EVEX encoded version: When VEX.W1 or EVEX.W1 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/EVEX.vvvv is reserved and must be 1111b otherwise instructions will #UD.

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.

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

SRC_OFFSET (cid:197) IMM8[1:0]
IF (64-Bit Mode and DEST is register)
    DEST[31:0] (cid:197) (SRC[127:0] >> (SRC_OFFSET*32)) AND 0FFFFFFFFh
    DEST[63:32] (cid:197) 0
    ELSE
    DEST[31:0] (cid:197) (SRC[127:0] >> (SRC_OFFSET*32)) AND 0FFFFFFFFh
FI

SRC_OFFSET (cid:197)IMM8[1:0]
IF (64-Bit Mode and DEST is register)
    DEST[31:0] (cid:197)(SRC[127:0] >> (SRC_OFFSET*32)) AND 0FFFFFFFFh
    DEST[63:32] (cid:197)0
    ELSE
    DEST[31:0] (cid:197)(SRC[127:0] >> (SRC_OFFSET*32)) AND 0FFFFFFFFh
FI

Intel C/C++ Compiler Intrinsic Equivalent

EXTRACTPS int _mm_extract_ps (__m128 a, const int nidx);

SIMD Floating-Point Exceptions

None

Other Exceptions