CMOV moves its source (second) operand into its destination
(first) operand if the given condition code is satisfied; otherwise
it does nothing.
For a list of condition codes, see the condition codes.
Although the CMOV instructions are flagged P6 and above, they
may not be supported by all Pentium Pro processors; the CPUID
instruction (CPUID) will return a bit which indicates whether
conditional moves are supported.