FUCOMPP    Unordered Compare and Pop Twice (80387)   Exception Flags: I D S

FUCOMPP

       Logic:      sets condition codes in the status word and then pops
                   twice:

                   C3 C2 C1 C0    Means
                   -- -- -- --    -----------
                   0  0  ?  0     ST > source
                   0  0  ?  1     ST < source
                   1  0  ?  0     ST = source
                   1  1  ?  1     unordered

     FUCOMPP compares ST and ST(1), leaves the result encoded in the
     status word as shown above, and pops the stack twice.

     FUCOMPP is like FCOMPP 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
   FUCOMPP             26              3              FUCOMPP
  --------------------------------------------------------------------------

        Note:          Use JP to test for an unordered comparison.