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FUCOMP Unordered Compare and Pop (80387) Exception Flags: I D S
FUCOMP [register]
Logic: sets condition codes in the status word as follows
and then pops the stack:
C3 C2 C1 C0 Means
-- -- -- -- -----------
0 0 ? 0 ST > source
0 0 ? 1 ST < source
1 0 ? 0 ST = source
1 1 ? 1 unordered
FUCOMP compares two registers, leaves the result encoded in the
status word as shown above, and pops the stack. If no source
register is specified, ST(1) is compared to ST. Otherwise, the
source register is compared to ST.
FUCOMP is like FCOMP except that it does not cause an invalid
operation exception if one of the operands is a NAN. Instead, it
sets the condition codes to give an unordered result.
--------------------------------------------------------------------------
Operands Clocks Bytes Example
FUCOMP reg 26 3 FUCOMP ST(1)
--------------------------------------------------------------------------
Note: Use JP to test for an unordered comparison.
See Also:
FCOM
FUCOM
FUCOMPP
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