Quick introduction to reverse engineering for beginners

.text:00541114 mov edi, 7 ; loop 1 counter is initial state 7
.text:00541119
.text:00541119 loc_541119:
.text:00541119 xor esi, esi ; loop 2 counter
.text:0054111B
.text:0054111B loc_54111B:
.text:0054111B mov al, [ebx+esi] ; get byte from internal array
.text:0054111E push eax
.text:0054111F push edi ; loop 1 counter
.text:00541120 push esi ; loop 2 counter
.text:00541121 push ebp ; arg_0
.text:00541122 call set_bit
.text:00541127 add esp, 10h
.text:0054112A inc esi ; increment loop 2 counter
.text:0054112B cmp esi, 8
.text:0054112E jl short loc_54111B
.text:00541130 dec edi ; decrement loop 2 counter
.text:00541131 add ebx, 8
.text:00541134 cmp edi, 0FFFFFFFFh
.text:00541137 jg short loc_541119
.text:00541139 pop edi
.text:0054113A pop esi
.text:0054113B pop ebp
.text:0054113C pop ebx
.text:0054113D add esp, 40h
.text:00541140 retn
.text:00541140 rotate2 endp
It is almost the same, except of different order of arguments of get_bit() and set_bit(). Let’s rewrite
it in C-like code:
void rotate2 (int v)
{
bool tmp[8][8]; // internal array
int i, j;
};
for (i=0; i