The document discusses how a for loop can be recognized in assembly code. It notes that a for loop contains instructions for changing a counter, comparing the counter, and making jumps. Specifically, a for loop in assembly would contain instructions that increment a counter, compare the counter to a limit, and make jumps to repeat the loop based on the comparison.

1. C++ for
operator

2. How does C++ for operator
truly look like

3. He doesn’t know this

4. She doesn’t know this either

5. ... he doesn’t even care

6. He definitely does!

7. do you

8. let’s take
x86 Microsoft
&
Assembler Visual C++
and have a look …

9. _main proc near
push esi
xor esi, esi
loc_401003:
void _tmain(int argc, _TCHAR* argv[])
push esi
{
push offset “%xquot;
for (int i = 0; i < 255; ++i)
call _printf
{
add esp, 8
printf(“%xquot;, i);
inc esi
}
cmp esi, 0FFh
}
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

10. _main proc near
push esi
xor esi, esi
loc_401003:
void _tmain(int argc, _TCHAR* argv[])
push esi
{
push offset “%xquot;
for (int i = 0; i < 255; ++i)
call _printf
{
add esp, 8
printf(“%xquot;, i);
inc esi
}
cmp esi, 0FFh
}
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

11. _main proc near
push esi
xor esi, esi
loc_401003:
void _tmain(int argc, _TCHAR* argv[])
push esi
{
push offset “%xquot;
for (int i = 0; i < 255; ++i)
call _printf
{
add esp, 8
printf(“%xquot;, i);
inc esi
}
cmp esi, 0FFh
}
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

12. _main proc near
push esi
xor esi, esi
loc_401003:
void _tmain(int argc, _TCHAR* argv[])
push esi
{
push offset “%xquot;
for (int i = 0; i < 255; ++i)
call _printf
{
add esp, 8
printf(“%xquot;, i);
inc esi
}
cmp esi, 0FFh
}
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

13. _main proc near
push esi
xor esi, esi
loc_401003:
void _tmain(int argc, _TCHAR* argv[])
push esi
{
push offset “%xquot;
for (int i = 0; i < 255; ++i)
call _printf
{
add esp, 8
printf(“%xquot;, i);
inc esi
}
cmp esi, 0FFh
}
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

14. _main proc near
push esi
xor esi, esi
loc_401003:
void _tmain(int argc, _TCHAR* argv[])
push esi
{
push offset “%xquot;
for (int i = 0; i < 255; ++i)
call _printf
{
add esp, 8
printf(“%xquot;, i);
inc esi
}
cmp esi, 0FFh
}
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

15. How it could have been
recognized in assembly

16. Quite simple. Just ...

17. by the presence of the
instructions of…
Counter changing
Counter comparison
Jumps

18. by the presence of the
instructions of…
Counter changing
Counter comparison
Jumps

19. _main proc near
push esi
xor esi, esi
loc_401003:
push esi
push offset “%xquot;
call _printf
add esp, 8
inc esi
cmp esi, 0FFh
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

20. _main proc near
push esi
xor esi, esi
loc_401003:
push esi
push offset “%xquot;
call _printf
add esp, 8
inc esi
cmp esi, 0FFh
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

21. by the presence of the
instructions of…
Counter changing
Counter comparison
Jumps

22. by the presence of the
instructions of…
Counter changing
Counter comparison
Jumps

23. _main proc near
push esi
xor esi, esi
loc_401003:
push esi
push offset “%xquot;
call _printf
add esp, 8
inc esi
cmp esi, 0FFh
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

24. _main proc near
push esi
xor esi, esi
loc_401003:
push esi
push offset “%xquot;
call _printf
add esp, 8
inc esi
cmp esi, 0FFh
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

25. by the presence of the
instructions of…
Counter changing
Counter comparison
Jumps

26. by the presence of the
instructions of…
Counter changing
Counter comparison
Jumps

27. _main proc near
push esi
xor esi, esi
loc_401003:
push esi
push offset “%xquot;
call _printf
add esp, 8
inc esi
cmp esi, 0FFh
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

28. _main proc near
push esi
xor esi, esi
loc_401003:
push esi
push offset “%xquot;
call _printf
add esp, 8
inc esi
cmp esi, 0FFh
jl short loc_401003
xor eax, eax
pop esi
retn
_main endp

29. by the presence of the
instructions of…
Counter changing
Counter comparison
Jumps

30. And once again …

31. for contains instructions of …
Counter changing
Counter comparison
Jumps

32. for contains instructions of …
Counter changing
Counter comparison
Jumps

33. for contains instructions of …
Counter changing
Counter comparison
Jumps

34. for contains instructions of …
Counter changing
Counter comparison
Jumps