Quick introduction to reverse engineering for beginners

call ___printf_chk
mov eax, esi
shr eax, 8
and eax, 0Fh
mov [esp+8], eax
mov dword ptr [esp+4], offset aFamily_idD ; "family_id=%d\n"
mov dword ptr [esp], 1
call ___printf_chk
mov eax, esi
shr eax, 0Ch
and eax, 3
mov [esp+8], eax
mov dword ptr [esp+4], offset aProcessor_type ; "processor_type=%d\n"
mov dword ptr [esp], 1
call ___printf_chk
mov eax, esi
shr eax, 10h
shr esi, 14h
and eax, 0Fh
and esi, 0FFh
mov [esp+8], eax
mov dword ptr [esp+4], offset aExtended_model ; "extended_model_id=%d\n"
mov dword ptr [esp], 1
call ___printf_chk
mov [esp+8], esi
mov dword ptr [esp+4], offset unk_80486D0
mov dword ptr [esp], 1
call ___printf_chk
add esp, 18h
xor eax, eax
pop ebx
pop esi
mov esp, ebp
pop ebp
retn
main endp
Almost the same. The only thing to note is that GCC somehow united calculation of extended_model_id
and extended_family_id into one block, instead of calculating them separately, before corresponding each
printf() call.
Working with the float type as with a structure
As it was already noted in section about FPU 1.12, both float and double types consisted of sign, significand
(or fraction) and exponent. But will we able to work with these fields directly? Let’s try with float.
#include
#include
Figure 1.1: float value format (illustration taken from wikipedia)
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