UNPCKLPS—Unpack and Interleave Low Packed Single-Precision Floating-Point Values

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

0F 14 /r

UNPCKLPS xmm1, xmm2/m128

 RM V/V SSE Unpacks and Interleaves single-precision floating-point values from low quadwords of xmm1 and xmm2/mem into xmm1.

VEX.NDS.128.0F.WIG 14 /r

VUNPCKLPS xmm1,xmm2, xmm3/m128

 RVM V/V AVX Unpacks and Interleaves single-precision floating-point values from low quadwords of xmm2 and xmm3/m128.

VEX.NDS.256.0F.WIG 14 /r

VUNPCKLPS ymm1,ymm2,ymm3/m256

 RVM V/V AVX Unpacks and Interleaves single-precision floating-point values from low quadwords of ymm2 and ymm3/m256.

Instruction Operand Encoding

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

Description

Performs an interleaved unpack of the low-order single-precision floating-point values from the source operand (second operand) and the destination operand (first operand). See Figure 4-26. The source operand can be an XMM register or a 128-bit memory location; the destination operand is an XMM register.

DEST SRC DEST X2 Y2 X3 X1 X0 Y3 Y1 Y0 Y1 X1 Y0

Figure 4-26. UNPCKLPS Instruction Low Unpack and Interleave Operation

When unpacking from a memory operand, an implementation may fetch only the appropriate 64 bits; however, alignment to 16-byte boundary and normal segment checking will still be enforced.

In 64-bit mode, using a REX prefix in the form of REX.R permits this instruction to access additional registers (XMM8-XMM15).

128-bit Legacy SSE version: The second source can be an XMM register or an 128-bit memory location. The desti-nation is not distinct from the first source XMM register and the upper bits (VLMAX-1:128) of the corresponding YMM register destination are unmodified.

VEX.128 encoded version: The first source operand is an XMM register or 128-bit memory location. The destination operand is an XMM register. The upper bits (VLMAX-1:128) of the corresponding YMM register destination are zeroed.

Operation

UNPCKLPS (128-bit Legacy SSE version)

DEST[31:0] ← SRC1[31:0]
DEST[63:32] ← SRC2[31:0]
DEST[95:64] ← SRC1[63:32]
DEST[127:96] ← SRC2[63:32]
DEST[VLMAX-1:128] (Unmodified)

VUNPCKLPS (VEX.128 encoded version)

DEST[31:0] ← SRC1[31:0]
DEST[63:32] ← SRC2[31:0]
DEST[95:64] ← SRC1[63:32]
DEST[127:96] ← SRC2[63:32]
DEST[VLMAX-1:128] ← 0
UNPCKLPS (VEX.256 encoded version)
DEST[31:0] ← SRC1[31:0]
DEST[63:32] ← SRC2[31:0]
DEST[95:64] ← SRC1[63:32]
DEST[127:96] ← SRC2[63:32]
DEST[159:128] ← SRC1[159:128]
DEST[191:160] ← SRC2[159:128]
DEST[223:192] ← SRC1[191:160]
DEST[255:224] ← SRC2[191:160]

Intel C/C++ Compiler Intrinsic Equivalent

UNPCKLPS:

__m128 _mm_unpacklo_ps(__m128 a, __m128 b)

UNPCKLPS:

__m256 _mm256_unpacklo_ps (__m256 a, __m256 b);

SIMD Floating-Point Exceptions

None.

Other Exceptions

See Exceptions Type 4.