FCOMI (Compare ST(0) to ST(i) and set CPU flags)

Syntax:    fcomi st,st(i)

Exception flags: Stack Fault, Invalid operation

Encoding:  DB  F0+i
Note: This instruction is valid only for the Pentium Pro and subsequent processors. It may not be supported by some assemblers (for MASM, the .686 directive must be used). The encoding is provided to facilitate hard-coding of this instruction if it is not supported by the assembler.
This instruction compares the content of ST(0) and ST(i), and then sets the ZF, PF and CF flags of the CPU's flag register according to the result of the comparison as follows:
                          ZF   PF   CF
     If ST(0) > ST(i)      0    0    0
     If ST(0) < ST(i)      0    0    1
     If ST(0) = ST(i)      1    0    0
     If ST(0) ? ST(i)      1    1    1
The condition codes field of the Status Word is not modified.