vpmovdb

Truncate Doubleword to Byte

VPMOVDB xmm1/m128 {k1}, zmm2

Down-converts 32-bit integers to 8-bit.

Details

Truncates 16 32-bit doubleword integers from a ZMM register down to 8-bit bytes, writing the 16 resulting bytes to an XMM register or 128-bit memory location. No flags are modified. Requires AVX-512F; the conversion is a simple truncation (low 8 bits extracted). Opmask k1 controls which byte results are written.

Pseudocode Operation

temp ← 0
for i in 0 to 15:
  if k1[i] == 1:
    temp[i*8 : (i+1)*8] ← ZMM2[i*32 : i*32+8]
  else if zeroing == true:
    temp[i*8 : (i+1)*8] ← 0
  else:
    temp[i*8 : (i+1)*8] ← temp[i*8 : (i+1)*8]
dest[0 : 128] ← temp[0 : 128]

Example

VPMOVDB xmm1/m128, zmm2

Encoding

Binary Layout

EVEX

Format EVEX

Opcode EVEX.512.F3.0F38.W0 31 /r

Extension AVX-512F

Operands

dest
128-bit XMM SIMD register or Memory operand
src
512-bit ZMM AVX-512 register

Reference (Intel® SDM)

Instruction Forms

Opcode	Instruction	Op/En	64/32-bit Mode	CPUID	Description
EVEX.128.F3.0F38.W0 31 /r	VPMOVDB xmm1/m32 {k1}{z}, xmm2	A	V/V	(AVX512VL AND AVX512F) OR AVX10.1	Converts 4 packed double-word integers from xmm2 into 4 packed byte integers in xmm1/m32 with truncation under writemask k1.
EVEX.128.F3.0F38.W0 21 /r	VPMOVSDB xmm1/m32 {k1}{z}, xmm2	A	V/V	(AVX512VL AND AVX512F) OR AVX10.1	Converts 4 packed signed double-word integers from xmm2 into 4 packed signed byte integers in xmm1/m32 using signed saturation under writemask k1.
EVEX.128.F3.0F38.W0 11 /r	VPMOVUSDB xmm1/m32 {k1}{z}, xmm2	A	V/V	(AVX512VL AND AVX512F) OR AVX10.1	Converts 4 packed unsigned double-word integers from xmm2 into 4 packed unsigned byte integers in xmm1/m32 using unsigned saturation under writemask k1.
EVEX.256.F3.0F38.W0 31 /r	VPMOVDB xmm1/m64 {k1}{z}, ymm2	A	V/V	(AVX512VL AND AVX512F) OR AVX10.1	Converts 8 packed double-word integers from ymm2 into 8 packed byte integers in xmm1/m64 with truncation under writemask k1.
EVEX.256.F3.0F38.W0 21 /r	VPMOVSDB xmm1/m64 {k1}{z}, ymm2	A	V/V	(AVX512VL AND AVX512F) OR AVX10.1	Converts 8 packed signed double-word integers from ymm2 into 8 packed signed byte integers in xmm1/m64 using signed saturation under writemask k1.
EVEX.256.F3.0F38.W0 11 /r	VPMOVUSDB xmm1/m64 {k1}{z}, ymm2	A	V/V	(AVX512VL AND AVX512F) OR AVX10.1	Converts 8 packed unsigned double-word integers from ymm2 into 8 packed unsigned byte integers in xmm1/m64 using unsigned saturation under writemask k1.
EVEX.512.F3.0F38.W0 31 /r	VPMOVDB xmm1/m128 {k1}{z}, zmm2	A	V/V	AVX512F OR AVX10.1	Converts 16 packed double-word integers from zmm2 into 16 packed byte integers in xmm1/m128 with truncation under writemask k1.
EVEX.512.F3.0F38.W0 21 /r	VPMOVSDB xmm1/m128 {k1}{z}, zmm2	A	V/V	AVX512F OR AVX10.1	Converts 16 packed signed double-word integers from zmm2 into 16 packed signed byte integers in xmm1/m128 using signed saturation under writemask k1.
EVEX.512.F3.0F38.W0 11 /r	VPMOVUSDB xmm1/m128 {k1}{z}, zmm2	A	V/V	AVX512F OR AVX10.1	Converts 16 packed unsigned double-word integers from zmm2 into 16 packed unsigned byte integers in xmm1/m128 using unsigned saturation under writemask k1.

Instruction Operand Encoding

Op/En	Tuple Type	Operand 1	Operand 2	Operand 3	Operand 4
A	Quarter Mem	ModRM:r/m (w)	ModRM:reg (r)	N/A	N/A

Description

VPMOVDB down converts 32-bit integer elements in the source operand (the second operand) into packed bytes using truncation. VPMOVSDB converts signed 32-bit integers into packed signed bytes using signed saturation. VPMOVUSDB convert unsigned double-word values into unsigned byte values using unsigned saturation. The source operand is a ZMM/YMM/XMM register. The destination operand is a XMM register or a 128/64/32-bit memory location. Down-converted byte elements are written to the destination operand (the first operand) from the least-significant byte. Byte elements of the destination operand are updated according to the writemask. Bits (MAXVL-1:128/64/32) of the register destination are zeroed. EVEX.vvvv is reserved and must be 1111b otherwise instructions will #UD.

Operation

VPMOVDB instruction (EVEX encoded versions) when dest is a register
(KL, VL) = (4, 128), (8, 256), (16, 512)
FOR j := 0 TO KL-1
i := j * 8
m := j * 32
IF k1[j] OR *no writemask*
THEN DEST[i+7:i] := TruncateDoubleWordToByte (SRC[m+31:m])
ELSE
IF *merging-masking*                                 ; merging-masking
THEN *DEST[i+7:i] remains unchanged*
ELSE *zeroing-masking*                            ; zeroing-masking
DEST[i+7:i] := 0
FI
FI;
ENDFOR
DEST[MAXVL-1:VL/4] := 0;

VPMOVDB instruction (EVEX encoded versions) when dest is memory
(KL, VL) = (4, 128), (8, 256), (16, 512)
FOR j := 0 TO KL-1
i := j * 8
m := j * 32
IF k1[j] OR *no writemask*
THEN DEST[i+7:i] := TruncateDoubleWordToByte (SRC[m+31:m])
ELSE *DEST[i+7:i] remains unchanged*                  ; merging-masking
FI;
ENDFOR

VPMOVSDB instruction (EVEX encoded versions) when dest is a register
(KL, VL) = (4, 128), (8, 256), (16, 512)
FOR j := 0 TO KL-1
i := j * 8
m := j * 32
IF k1[j] OR *no writemask*
THEN DEST[i+7:i] := SaturateSignedDoubleWordToByte (SRC[m+31:m])
ELSE
IF *merging-masking*                                 ; merging-masking
THEN *DEST[i+7:i] remains unchanged*
ELSE *zeroing-masking*                            ; zeroing-masking
DEST[i+7:i] := 0
FI


VPMOVDB/VPMOVSDB/VPMOVUSDB—Down Convert DWord to Byte                                                                           Vol. 2C 5-578
FI;
ENDFOR
DEST[MAXVL-1:VL/4] := 0;

VPMOVSDB instruction (EVEX encoded versions) when dest is memory
(KL, VL) = (4, 128), (8, 256), (16, 512)
FOR j := 0 TO KL-1
i := j * 8
m := j * 32
IF k1[j] OR *no writemask*
THEN DEST[i+7:i] := SaturateSignedDoubleWordToByte (SRC[m+31:m])
ELSE *DEST[i+7:i] remains unchanged*                  ; merging-masking
FI;
ENDFOR

VPMOVUSDB instruction (EVEX encoded versions) when dest is a register
(KL, VL) = (4, 128), (8, 256), (16, 512)
FOR j := 0 TO KL-1
i := j * 8
m := j * 32
IF k1[j] OR *no writemask*
THEN DEST[i+7:i] := SaturateUnsignedDoubleWordToByte (SRC[m+31:m])
ELSE
IF *merging-masking*                                 ; merging-masking
THEN *DEST[i+7:i] remains unchanged*
ELSE *zeroing-masking*                            ; zeroing-masking
DEST[i+7:i] := 0
FI
FI;
ENDFOR
DEST[MAXVL-1:VL/4] := 0;

VPMOVUSDB instruction (EVEX encoded versions) when dest is memory
(KL, VL) = (4, 128), (8, 256), (16, 512)
FOR j := 0 TO KL-1
i := j * 8
m := j * 32
IF k1[j] OR *no writemask*
THEN DEST[i+7:i] := SaturateUnsignedDoubleWordToByte (SRC[m+31:m])
ELSE *DEST[i+7:i] remains unchanged*                  ; merging-masking
FI;
ENDFOR





VPMOVDB/VPMOVSDB/VPMOVUSDB—Down Convert DWord to Byte                                                                           Vol. 2C 5-579

Intel C/C++ Compiler Intrinsic Equivalent

VPMOVDB __m128i _mm512_cvtepi32_epi8( __m512i a);
VPMOVDB __m128i _mm512_mask_cvtepi32_epi8(__m128i s, __mmask16 k, __m512i a);
VPMOVDB __m128i _mm512_maskz_cvtepi32_epi8( __mmask16 k, __m512i a);
VPMOVDB void _mm512_mask_cvtepi32_storeu_epi8(void * d, __mmask16 k, __m512i a);
VPMOVSDB __m128i _mm512_cvtsepi32_epi8( __m512i a);
VPMOVSDB __m128i _mm512_mask_cvtsepi32_epi8(__m128i s, __mmask16 k, __m512i a);
VPMOVSDB __m128i _mm512_maskz_cvtsepi32_epi8( __mmask16 k, __m512i a);
VPMOVSDB void _mm512_mask_cvtsepi32_storeu_epi8(void * d, __mmask16 k, __m512i a);
VPMOVUSDB __m128i _mm512_cvtusepi32_epi8( __m512i a);
VPMOVUSDB __m128i _mm512_mask_cvtusepi32_epi8(__m128i s, __mmask16 k, __m512i a);
VPMOVUSDB __m128i _mm512_maskz_cvtusepi32_epi8( __mmask16 k, __m512i a);
VPMOVUSDB void _mm512_mask_cvtusepi32_storeu_epi8(void * d, __mmask16 k, __m512i a);
VPMOVUSDB __m128i _mm256_cvtusepi32_epi8(__m256i a);
VPMOVUSDB __m128i _mm256_mask_cvtusepi32_epi8(__m128i a, __mmask8 k, __m256i b);
VPMOVUSDB __m128i _mm256_maskz_cvtusepi32_epi8( __mmask8 k, __m256i b);
VPMOVUSDB void _mm256_mask_cvtusepi32_storeu_epi8(void * , __mmask8 k, __m256i b);
VPMOVUSDB __m128i _mm_cvtusepi32_epi8(__m128i a);
VPMOVUSDB __m128i _mm_mask_cvtusepi32_epi8(__m128i a, __mmask8 k, __m128i b);
VPMOVUSDB __m128i _mm_maskz_cvtusepi32_epi8( __mmask8 k, __m128i b);
VPMOVUSDB void _mm_mask_cvtusepi32_storeu_epi8(void * , __mmask8 k, __m128i b);
VPMOVSDB __m128i _mm256_cvtsepi32_epi8(__m256i a);
VPMOVSDB __m128i _mm256_mask_cvtsepi32_epi8(__m128i a, __mmask8 k, __m256i b);
VPMOVSDB __m128i _mm256_maskz_cvtsepi32_epi8( __mmask8 k, __m256i b);
VPMOVSDB void _mm256_mask_cvtsepi32_storeu_epi8(void * , __mmask8 k, __m256i b);
VPMOVSDB __m128i _mm_cvtsepi32_epi8(__m128i a);
VPMOVSDB __m128i _mm_mask_cvtsepi32_epi8(__m128i a, __mmask8 k, __m128i b);
VPMOVSDB __m128i _mm_maskz_cvtsepi32_epi8( __mmask8 k, __m128i b);
VPMOVSDB void _mm_mask_cvtsepi32_storeu_epi8(void * , __mmask8 k, __m128i b);
VPMOVDB __m128i _mm256_cvtepi32_epi8(__m256i a);
VPMOVDB __m128i _mm256_mask_cvtepi32_epi8(__m128i a, __mmask8 k, __m256i b);
VPMOVDB __m128i _mm256_maskz_cvtepi32_epi8( __mmask8 k, __m256i b);
VPMOVDB void _mm256_mask_cvtepi32_storeu_epi8(void * , __mmask8 k, __m256i b);
VPMOVDB __m128i _mm_cvtepi32_epi8(__m128i a);
VPMOVDB __m128i _mm_mask_cvtepi32_epi8(__m128i a, __mmask8 k, __m128i b);
VPMOVDB __m128i _mm_maskz_cvtepi32_epi8( __mmask8 k, __m128i b);
VPMOVDB void _mm_mask_cvtepi32_storeu_epi8(void * , __mmask8 k, __m128i b);

Exceptions

SIMD Floating-Point Exceptions

None.

Other Exceptions

EVEX-encoded instruction, see Table 2-55, “Type E6 Class Exception Conditions.” Additionally: #UD If EVEX.vvvv != 1111B. VPMOVDB/VPMOVSDB/VPMOVUSDB—Down Convert DWord to Byte Vol. 2C 5-580