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3-668 Vol. 2A MOVS/MOVSB/MOVSW/MOVSD/MOVSQ—Move Data from String to String
INSTRUCTION SET REFERENCE, A-M
MOVS/MOVSB/MOVSW/MOVSD/MOVSQ—Move Data from
String to String
\
Description
Moves the byte, word, or doubleword specified with the second operand (source
operand) to the location specified with the first operand (destination operand). Both
the source and destination operands are located in memory. The address of the
source operand is read from the DS:ESI or the DS:SI registers (depending on the
address-size attribute of the instruction, 32 or 16, respectively). The address of the
destination operand is read from the ES:EDI or the ES:DI registers (again depending
on the address-size attribute of the instruction). The DS segment may be overridden
with a segment override prefix, but the ES segment cannot be overridden.
Opcode Instruction 64-Bit
Mode
Compat/
Leg Mode
Description
A4 MOVS m8, m8 Valid Valid For legacy mode, Move byte from
address DS:(E)SI to ES:(E)DI. For 64-bit
mode move byte from address (R|E)SI
to (R|E)DI.
A5 MOVS m16, m16 Valid Valid For legacy mode, move word from
address DS:(E)SI to ES:(E)DI. For 64-bit
mode move word at address (R|E)SI to
(R|E)DI.
A5 MOVS m32, m32 Valid Valid For legacy mode, move dword from
address DS:(E)SI to ES:(E)DI. For 64-bit
mode move dword from address (R|E)SI
to (R|E)DI.
REX.W + A5 MOVS m64, m64 Valid N.E. Move qword from address (R|E)SI to
(R|E)DI.
A4 MOVSB Valid Valid For legacy mode, Move byte from
address DS:(E)SI to ES:(E)DI. For 64-bit
mode move byte from address (R|E)SI
to (R|E)DI.
A5 MOVSW Valid Valid For legacy mode, move word from
address DS:(E)SI to ES:(E)DI. For 64-bit
mode move word at address (R|E)SI to
(R|E)DI.
A5 MOVSD Valid Valid For legacy mode, move dword from
address DS:(E)SI to ES:(E)DI. For 64-bit
mode move dword from address (R|E)SI
to (R|E)DI.
REX.W + A5 MOVSQ Valid N.E. Move qword from address (R|E)SI to
(R|E)DI.