모두의 코드
FABS (Intel x86/64 assembly instruction)

작성일 : 2020-09-01 이 글은 711 번 읽혔습니다.

FABS

Absolute Value

참고 사항

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

Opcode

Instruction

64-Bit
Mode

Compat/
Leg Mode

Description

D9 E1

FABS

Valid

Valid

Replace ST with its absolute value.

Description

Clears the sign bit of ST(0) to create the absolute value of the operand. The following table shows the results obtained when creating the absolute value of various classes of numbers.

Table 3-17. Results Obtained from FABS

ST(0) SRC

ST(0) DEST

- $\infty$

+ $\infty$

- F

+ F

- 0

+ 0

+ 0

+ 0

+ F

+ F

+ $\infty$

+ $\infty$

NaN

NaN

NOTES:

F Means finite floating-point value.

This instruction's operation is the same in non-64-bit modes and 64-bit mode.

Operation

ST(0) <- |ST(0)|;

FPU Flags Affected

C1 Set to 0.

C0, C2, C3 Undefined.

Floating-Point Exceptions

#IS Stack underflow occurred.

Protected Mode Exceptions

#NM

  • CR0.EM[bit 2] or CR0.TS[bit 3] = 1.

#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

Same exceptions as in protected mode.

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