Does ADD EAX, EBX put to zero the 32 high-order bits of EAX if I just operate on the 32 low bits?
And what about ADD RAX, EBX? Is it possible? And if it is, are the 32 high-order bits of RAX preserved?
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Does ADD EAX, EBX put to zero the 32 high-order bits of EAX if I just operate on the 32 low bits?
And what about ADD RAX, EBX? Is it possible? And if it is, are the 32 high-order bits of RAX preserved?
ADD EAX, EBXzeros the high 32 bits of RAX.ADD RAX, EBXis not a valid instruction.It sounds like you want to add a 32-bit value in
EBXto a 64-bit value inRAX. To do this, first you either zero-extend (MOV EBX, EBX) or sign-extend (MOVSX RBX, EBX), then addRBXtoRAX. (Use zero-extension if you are interpreting the value inEBXas unsigned, sign-extension if it is signed).