FBLD

Load Binary Coded Decimal

참고 사항

Description

Converts the BCD source operand into double extended-precision floating-point format and pushes the value onto the FPU stack. The source operand is loaded without rounding errors. The sign of the source operand is preserved, including that of -0.

The packed BCD digits are assumed to be in the range 0 through 9; the instruction does not check for invalid digits (AH through FH). Attempting to load an invalid encoding produces an undefined result.

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

Operation

TOP <- TOP - 1;
ST(0) <- ConvertToDoubleExtendedPrecisionFP(SRC); 

FPU Flags Affected

C1 Set to 1 if stack overflow occurred; otherwise, set to 0.

C0, C2, C3 Undefined.

Floating-Point Exceptions

#IS Stack overflow occurred.

Protected Mode Exceptions

#GP(0)

• If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.

• If the DS, ES, FS, or GS register contains a NULL segment selector.

#SS(0)

• If a memory operand effective address is outside the SS segment limit.

#NM

• CR0.EM[bit 2] or CR0.TS[bit 3] = 1.

#PF(fault-code)

• If a page fault occurs.

#AC(0)

• If alignment checking is enabled and an unaligned memory reference is made while the current privilege level is 3.

#UD

• If the LOCK prefix is used.

Real-Address Mode Exceptions

#GP

• If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.

#SS

• If a memory operand effective address is outside the SS segment limit.

#NM

• CR0.EM[bit 2] or CR0.TS[bit 3] = 1.

#UD

• If the LOCK prefix is used.

Virtual-8086 Mode Exceptions

#GP(0)

• If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.

#SS(0)

• If a memory operand effective address is outside the SS segment limit.

#NM

• CR0.EM[bit 2] or CR0.TS[bit 3] = 1.

#PF(fault-code)

• If a page fault occurs.

#AC(0)

• If alignment checking is enabled and an unaligned memory reference is made.

#UD

• If the LOCK prefix is used.

Compatibility Mode Exceptions

Same exceptions as in protected mode.

64-Bit Mode Exceptions

#SS(0)

• If a memory address referencing the SS segment is in a non-canonical form.

#GP(0)

• If the memory address is in a non-canonical form.

#NM

• CR0.EM[bit 2] or CR0.TS[bit 3] = 1.

#MF

• If there is a pending x87 FPU exception.

#PF(fault-code)

• If a page fault occurs.

#AC(0)

• If alignment checking is enabled and an unaligned memory reference is made while the current privilege level is 3.

#UD

• If the LOCK prefix is used.

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