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.
Every form of cmovnb the assembler accepts, from NASM's own instruction table.
The second column is the processor that introduced the form; a badge marks a form that needs
an extension, that is lockable, or that long mode dropped.
| Form | Since | Notes |
|---|---|---|
| cmovnb reg16, r/m16 | Pentium Pro | |
| cmovnb reg32, r/m32 | Pentium Pro | |
| cmovnb reg64, r/m64 | x86-64 | long |
| cmovnb reg16, reg16, r/m16 | x86-64 | apxlong |
| cmovnb reg32, reg32, r/m32 | x86-64 | apxlong |
| cmovnb reg64, reg64, r/m64 | x86-64 | apxlong |
