Author: Eugene Nalimov
Date: 22:32:28 01/26/99
Go up one level in this thread
On January 26, 1999 at 22:38:37, James Robertson wrote:
>Once again I show my absolute ignorance of assembly with these two questions:
>I am trying to acces the 3rd [+ 4th] byte of a register. How? E.g., what is next
>after al, ah, ?
>How do I pop something off the stack without moving the stack pointer?
>
>Thanks,
>James
1. Use shift instruction. E.g.
shr eax, 16
mov byte ptr [esi], al
You can also use rotate instruction (it'll not destruct
other bytes):
ror eax, 16
mov byte ptr [esi], al
ror eax, 16
But if I remember it correctly, rotate is worse than shift
(cannot be executed in parallel) on both Pentium and P6 family.
2. mov reg32, dword ptr [esp]
Eugene
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