insertps

Insert Packed Single-Precision

INSERTPS xmm1, xmm2/m32, imm8

Inserts a single float into a specific index of XMM.

Details

Inserts a single 32-bit float from a source (register or memory) into a specific lane of the destination XMM register as specified by bits [5:4] of the immediate operand, and optionally zeros lanes specified by bits [3:0]. No CPU flags are affected by this SIMD operation, which is part of the SSE4.1 extension.

Pseudocode Operation

imm ← imm8;
count_d ← (imm >> 4) & 0x3;
zero_mask ← imm & 0xF;
src_dword ← src[31:0];
xmm1[count_d*32 + 31 : count_d*32] ← src_dword;
for i in 0 to 3:
  if (zero_mask & (1 << i)) then xmm1[i*32 + 31 : i*32] ← 0;

Example

INSERTPS xmm1, xmm2/m32, 3

Encoding

Binary Layout

Format SSE4.1

Opcode 66 0F 3A 21

Extension SSE4.1

Operands

dest
128-bit XMM SIMD register
src1
128-bit XMM SIMD register or Memory operand
src2
8-bit signed immediate

Reference (Intel® SDM)

Instruction Forms

Opcode	Instruction	Op/En	64/32-bit Mode	CPUID	Description
66 0F 3A 21 /r ib	INSERTPS xmm1, xmm2/m32, imm8	A	V/V	SSE4_1	Insert a single precision floating-point value selected by imm8 from xmm2/m32 into xmm1 at the specified destination element specified by imm8 and zero out destination elements in xmm1 as indicated in imm8.
VEX.128.66.0F3A.WIG 21 /r ib	VINSERTPS xmm1, xmm2, xmm3/m32, imm8	B	V/V	AVX	Insert a single precision floating-point value selected by imm8 from xmm3/m32 and merge with values in xmm2 at the specified destination element specified by imm8 and write out the result and zero out destination elements in xmm1 as indicated in imm8.
EVEX.128.66.0F3A.W0 21 /r ib	VINSERTPS xmm1, xmm2, xmm3/m32, imm8	C	V/V	AVX512F OR AVX10.1	Insert a single precision floating-point value selected by imm8 from xmm3/m32 and merge with values in xmm2 at the specified destination element specified by imm8 and write out the result and zero out destination elements in xmm1 as indicated in imm8.

Instruction Operand Encoding

Op/En	Tuple Type	Operand 1	Operand 2	Operand 3	Operand 4
A	N/A	ModRM:reg (r, w)	ModRM:r/m (r)	imm8	N/A
B	N/A	ModRM:reg (w)	VEX.vvvv (r)	ModRM:r/m (r)	imm8
C	Tuple1 Scalar	ModRM:reg (w)	EVEX.vvvv (r)	ModRM:r/m (r)	imm8

Description

(register source form) Copy a single precision scalar floating-point element into a 128-bit vector register. The immediate operand has three fields, where the ZMask bits specify which elements of the destination will be set to zero, the Count_D bits specify which element of the destination will be overwritten with the scalar value, and for vector register sources the Count_S bits specify which element of the source will be copied. When the scalar source is a memory operand the Count_S bits are ignored. (memory source form) Load a floating-point element from a 32-bit memory location and destination operand it into the first source at the location indicated by the Count_D bits of the immediate operand. Store in the destination and zero out destination elements based on the ZMask bits of the immediate operand. 128-bit Legacy SSE version: The first source register is an XMM register. The second source operand is either an XMM register or a 32-bit memory location. The destination is not distinct from the first source XMM register and the upper bits (MAXVL-1:128) of the corresponding register destination are unmodified. VEX.128 and EVEX encoded version: The destination and first source register is an XMM register. The second source operand is either an XMM register or a 32-bit memory location. The upper bits (MAXVL-1:128) of the corresponding register destination are zeroed. If VINSERTPS is encoded with VEX.L= 1, an attempt to execute the instruction encoded with VEX.L= 1 will cause an #UD exception. INSERTPS—Insert Scalar Single Precision Floating-Point Value Vol. 2A 3-461

Operation

VINSERTPS (VEX.128 and EVEX Encoded Version)
IF (SRC = REG) THEN COUNT_S := imm8[7:6]
ELSE COUNT_S := 0
COUNT_D := imm8[5:4]
ZMASK := imm8[3:0]
CASE (COUNT_S) OF
0: TMP := SRC2[31:0]
1: TMP := SRC2[63:32]
2: TMP := SRC2[95:64]
3: TMP := SRC2[127:96]
ESAC;
CASE (COUNT_D) OF
0: TMP2[31:0] := TMP
TMP2[127:32] := SRC1[127:32]
1: TMP2[63:32] := TMP
TMP2[31:0] := SRC1[31:0]
TMP2[127:64] := SRC1[127:64]
2: TMP2[95:64] := TMP
TMP2[63:0] := SRC1[63:0]
TMP2[127:96] := SRC1[127:96]
3: TMP2[127:96] := TMP
TMP2[95:0] := SRC1[95:0]
ESAC;

IF (ZMASK[0] = 1) THEN DEST[31:0] := 00000000H
ELSE DEST[31:0] := TMP2[31:0]
IF (ZMASK[1] = 1) THEN DEST[63:32] := 00000000H
ELSE DEST[63:32] := TMP2[63:32]
IF (ZMASK[2] = 1) THEN DEST[95:64] := 00000000H
ELSE DEST[95:64] := TMP2[95:64]
IF (ZMASK[3] = 1) THEN DEST[127:96] := 00000000H
ELSE DEST[127:96] := TMP2[127:96]
DEST[MAXVL-1:128] := 0

INSERTPS (128-bit Legacy SSE Version)
IF (SRC = REG) THEN COUNT_S :=imm8[7:6]
ELSE COUNT_S :=0
COUNT_D := imm8[5:4]
ZMASK := imm8[3:0]
CASE (COUNT_S) OF
0: TMP := SRC[31:0]
1: TMP := SRC[63:32]
2: TMP := SRC[95:64]
3: TMP := SRC[127:96]
ESAC;

CASE (COUNT_D) OF
0: TMP2[31:0] := TMP
TMP2[127:32] := DEST[127:32]
1: TMP2[63:32] := TMP
TMP2[31:0] := DEST[31:0]
TMP2[127:64] := DEST[127:64]
2: TMP2[95:64] := TMP


INSERTPS—Insert Scalar Single Precision Floating-Point Value                                                                                  Vol. 2A 3-462
TMP2[63:0] := DEST[63:0]
TMP2[127:96] := DEST[127:96]
3: TMP2[127:96] := TMP
TMP2[95:0] := DEST[95:0]
ESAC;

IF (ZMASK[0] = 1) THEN DEST[31:0] := 00000000H
ELSE DEST[31:0] := TMP2[31:0]
IF (ZMASK[1] = 1) THEN DEST[63:32] := 00000000H
ELSE DEST[63:32] := TMP2[63:32]
IF (ZMASK[2] = 1) THEN DEST[95:64] := 00000000H
ELSE DEST[95:64] := TMP2[95:64]
IF (ZMASK[3] = 1) THEN DEST[127:96] := 00000000H
ELSE DEST[127:96] := TMP2[127:96]
DEST[MAXVL-1:128] (Unmodified)

Intel C/C++ Compiler Intrinsic Equivalent

VINSERTPS __m128 _mm_insert_ps(__m128 dst, __m128 src, const int nidx);
INSETRTPS __m128 _mm_insert_ps(__m128 dst, __m128 src, const int nidx);

Exceptions

SIMD Floating-Point Exceptions

None.

Other Exceptions

Non-EVEX-encoded instruction, see Table 2-22, “Type 5 Class Exception Conditions,” additionally: #UD If VEX.L = 0. EVEX-encoded instruction, see Table 2-59, “Type E9NF Class Exception Conditions.” INSERTPS—Insert Scalar Single Precision Floating-Point Value Vol. 2A 3-463