모두의 코드
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모두의 코드
LAHF (Intel x86/64 assembly instruction)

작성일 : 2020-09-01 이 글은 891 번 읽혔습니다.

LAHF

Load Status Flags into AH Register

참고 사항

아래 표를 해석하는 방법은 x86-64 명령어 레퍼런스 읽는 법 글을 참조하시기 바랍니다.

Opcode

Instruction

Op/
En

64-Bit
Mode

Compat/
Leg Mode

Description

9F

LAHF

NP

Invalid*

Valid

Load: AH <- EFLAGS(SF:ZF:0:AF:0:PF:1:CF).

*Valid in specific steppings. See Description section

Instruction Operand Encoding

Op/En

Operand 1

Operand 2

Operand 3

Operand 4

NP

NA

NA

NA

NA

Description

This instruction executes as described above in compatibility mode and legacy mode. It is valid in 64-bit mode only if CPUID.80000001H:ECX.LAHF-SAHF[bit 0] = 1.

Operation

IF 64-Bit ModeTHENIF CPUID.80000001H:ECX.LAHF-SAHF[bit 0] = 1;THEN AH <- RFLAGS(SF:ZF:0:AF:0:PF:1:CF);ELSE #UD; FI;ELSEAH <- EFLAGS(SF:ZF:0:AF:0:PF:1:CF);FI;

Flags Affected

None. The state of the flags in the EFLAGS register is not affected.

Protected Mode Exceptions

#UD

  • If the LOCK prefix is used.

Real-Address Mode Exceptions

Same exceptions as in protected mode.

Virtual-8086 Mode Exceptions

Same exceptions as in protected mode.

Compatibility Mode Exceptions

Same exceptions as in protected mode.

64-Bit Mode Exceptions

#UD

  • If CPUID.80000001H:ECX.LAHF-SAHF[bit 0] = 0.

  • If the LOCK prefix is used.

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