Intel 64 and IA-32 Architectures Software Developers Manual Volume 2A, Instruction Set Reference, A-M

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INSTRUCTION SET REFERENCE, A-M
CMC—Complement Carry Flag
Description
Complements the CF flag in the EFLAGS register. CMC operation is the same in non-
64-bit modes and 64-bit mode.
Operation
EFLAGS.CF[bit 0]← NOT EFLAGS.CF[bit 0];
Flags Affected
The CF flag contains the complement of its original value. The OF, ZF, SF, AF, and PF
flags are unaffected.
Exceptions (All Operating Modes)
None.
Opcode Instruction
64-Bit
Mode
Compat/
Leg Mode Description
F5 CMC Valid Valid Complement CF flag.