Quick introduction to reverse engineering for beginners

_value$ = 20 ; size = 4
_insert PROC
push ebp
mov ebp, esp
mov eax, DWORD PTR _x$[ebp]
imul eax, 2400 ; 00000960H
mov ecx, DWORD PTR _y$[ebp]
imul ecx, 120 ; 00000078H
lea edx, DWORD PTR _a[eax+ecx]
mov eax, DWORD PTR _z$[ebp]
mov ecx, DWORD PTR _value$[ebp]
mov DWORD PTR [edx+eax*4], ecx
pop ebp
ret 0
_insert ENDP
_TEXT ENDS
Nothing special. For index calculation, three input arguments are multiplying in such way to represent
array as multidimensional.
GCC 4.4.1:
public insert
insert proc near
x = dword ptr 8
y = dword ptr 0Ch
z = dword ptr 10h
value = dword ptr 14h
push ebp
mov ebp, esp
push ebx
mov ebx, [ebp+x]
mov eax, [ebp+y]
mov ecx, [ebp+z]
lea edx, [eax+eax]
mov eax, edx
shl eax, 4
sub eax, edx
imul edx, ebx, 600
add eax, edx
lea edx, [eax+ecx]
mov eax, [ebp+value]
mov dword ptr ds:a[edx*4], eax
pop ebx
pop ebp
retn
insert endp
53