3-169
INSTRUCTION SET REFERENCE
FBLDLoad Binary Coded Decimal
Description
This instruction converts the BCD source operand into extended-real 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)
<
ExtendedReal(SRC);
FPU Flags Affected
C1
Set to 1 if stack overflow occurred; otherwise, cleared 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
EM or TS in CR0 is set.
#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.
Opcode
Instruction
Description
DF /4
FBLD m80 dec
Convert BCD value to real and push onto the FPU stack.
