FBLD
Load Binary Coded Decimal
stableVMJITAOTinstruction
Encodings
| Opcode | Instruction | Op/En | 64-bit | Compat/Legacy | Description |
|---|---|---|---|---|---|
DF /4 | FBLD m80bcd | Valid | Valid | Convert BCD value to floating-point and push onto the FPU stack. |
Measured cost
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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.Exceptions
Protected mode
#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
#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
#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
| Same exceptions as in protected mode. |
64-bit mode
#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. |