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StanfordPL / x64asm

x86-64 assembler library
Apache License 2.0
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MOV AL and REX prefix #209

Closed avikivity closed 8 years ago

avikivity commented 8 years ago

Your README states: "The Intel manual is unclear on what adding the REX.w+ prefix to MOV [mem8] AL accomplishes, but we support this behavior nonetheless."

The REX prefix is used to select from the register set AL/BL/CL/DL/SIL/DIL...R15L compared to the default of AL/AH...DL/DH.

stefanheule commented 8 years ago

Hey. Thanks, we are aware of what the REX prefix normally is used for. However, the statement in the README is about the particular MOV variant for the AL register. There is no choice between register sets in this case, which is why the README points this out.