Difference between revisions of "CSC231 No-no! and Be-Careful! situations"
(→What's tricky about the following code?) |
(→What's tricky about the following code?) |
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| Line 31: | Line 31: | ||
compute: | compute: | ||
pushad | pushad | ||
| − | push | + | push ebp |
| − | mov | + | mov ebp, esp |
;;; get parameters from the stack | ;;; get parameters from the stack | ||
| Line 45: | Line 45: | ||
;;; we're done | ;;; we're done | ||
| − | pop | + | pop ebp |
popad | popad | ||
ret 3*4 | ret 3*4 | ||
Revision as of 08:18, 10 November 2010
--D. Thiebaut 13:15, 10 November 2010 (UTC)
What's wrong with the following code?
;------------------------------------------------------------------
; function that pushes several results in the stack
;------------------------------------------------------------------
compute:
pushad
mov ecx, N ;loop some number of times
mov eax, data1 ;get some data
mov ebx, data2
.for: call doSomething ;operate on eax and ebx
; on return, eax contains
; result we're interested in
push eax ;save result in stack
loop .for
;;; we're done
popad
ret
What's tricky about the following code?
compute:
pushad
push ebp
mov ebp, esp
;;; get parameters from the stack
mov ecx,[ebp+XX] ;XX is some offset
mov eax,[ebp+YY] ;YY is some offset
mov ebx,[ebp+ZZ] ;ZZ is some offset
.for: call doSomething ;operate on eax and ebx
; on return, eax contains
; result we're interested in
loop .for
;;; we're done
pop ebp
popad
ret 3*4
