x86 Instruction Set Reference

FBLD

Load Binary Coded Decimal

Opcode	Mnemonic	Description
`DF /4`	`FBLD m80`	dec Convert BCD value to floating-point and push onto the FPU stack.

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.

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.

Operation
TOP = TOP - 1; ST(0) = ConvertToExtendedDouble(Source);

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.
`#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`	EM or TS in CR0 is set.
`#PF(fault-code)`	If a page fault occurs.

Real-Address Mode Exceptions

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

Virtual-8086 Mode Exceptions

`#GP(0)`	If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.
`#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`	EM or TS in CR0 is set.
`#PF(fault-code)`	If a page fault occurs.