Quick introduction to reverse engineering for beginners

1.8 switch()/case/default
1.8.1 Few number of cases
void f (int a)
{
switch (a)
{
case 0: printf ("zero\n"); break;
case 1: printf ("one\n"); break;
case 2: printf ("two\n"); break;
default: printf ("something unknown\n"); break;
};
};
Result (MSVC 2010):
tv64 = -4 ; size = 4
_a$ = 8 ; size = 4
_f PROC
push ebp
mov ebp, esp
push ecx
mov eax, DWORD PTR _a$[ebp]
mov DWORD PTR tv64[ebp], eax
cmp DWORD PTR tv64[ebp], 0
je SHORT $LN4@f
cmp DWORD PTR tv64[ebp], 1
je SHORT $LN3@f
cmp DWORD PTR tv64[ebp], 2
je SHORT $LN2@f
jmp SHORT $LN1@f
$LN4@f:
push OFFSET $SG739 ; ’zero’, 0aH, 00H
call _printf
add esp, 4
jmp SHORT $LN7@f
$LN3@f:
push OFFSET $SG741 ; ’one’, 0aH, 00H
call _printf
add esp, 4
jmp SHORT $LN7@f
$LN2@f:
push OFFSET $SG743 ; ’two’, 0aH, 00H
call _printf
add esp, 4
jmp SHORT $LN7@f
$LN1@f:
push OFFSET $SG745 ; ’something unknown’, 0aH, 00H
call _printf
add esp, 4
$LN7@f:
mov esp, ebp
pop ebp
ret 0
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