cmpxchg16b

x86-64 and later

Compare and Exchange 16 Bytes

cmpxchg16b mem128

Compare and Exchange 16 Bytes

No example here: this instruction either stops the program, or belongs to a mode this emulator does not run.

Forms

Every form of cmpxchg16b 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.

FormSinceNotes
cmpxchg16b mem128x86-64locklong