Data Transfer Instructions
When stored in memory the bytes, words, and
doublewords in the packed data types are stored in consecutive addresses,
with the least significant byte, word, or doubleword being stored in the
lowest address and the more significant bytes, words, or doubleword being
stored at consecutively higher addresses. The ordering of bytes, words,
or doublewords in memory is always little endian: the bytes with the lower
addresses are less significant than the bytes with the higher addresses.
MOVD mm, r/m32
MOVD r/m32, mm
|The MOVD (Move 32 Bits) instruction
copies 32 bits from the source operand to the destination operand.
The destination and source operands can be either MMX registers, 32-bit
memory operands, or 32-bit integer registers. MOVD cannot transfer data
from an MMX register to an MMX register, from memory to memory, or from
an integer register to an integer register.
When the destination operand is an MMX
register, the 32-bit source operand is written to the low-order 32 bits
of the 64-bit destination register, and the high-order 32 bits of the destination
register are filled with zeros. When the source operand is an MMX register,
the low-order 32 bits of the MMX register are written to the 32-bit integer
register or 32-bit memory location.
|MOVD instruction when destination operand is MMX
DEST[31-0] ← SRC;
DEST[63-32] ← 00000000H;
MOVD instruction when source operand is MMX register:
DEST ← SRC[31-0];
|MOVD __m64 _mm_cvtsi32_si64 (int i )
MOVD int _mm_cvtsi64_si32 ( __m64m )
MOVQ mm, mm/m64
MOVQ mm/m64, mm
|The MOVQ (Move 64 Bits) instruction
copies 64 bits from the source operand to the destination operand. The
destination and source operands can be either MMX registers or 64-bit memory
operands, but MOVQ cannot transfer data from memory to memory.
|MOVQ instruction when operating on MMX registers and
DEST ← SRC;