Quick introduction to reverse engineering for beginners

loc_8048444:
loc_8048448:
loc_8048451:
loc_8048471:
and eax, 2000h
test eax, eax
jnz short loc_804840C
mov eax, [ebp+input]
mov eax, [eax]
mov [ebp+var_9], al
cmp [ebp+var_9], ’+’
jz short loc_8048444
cmp [ebp+var_9], ’-’
jnz short loc_8048448
add [ebp+input], 4
mov [ebp+var_10], 0
jmp short loc_8048471
mov edx, [ebp+var_10]
mov eax, edx
shl eax, 2
add eax, edx
add eax, eax
mov edx, eax
mov eax, [ebp+input]
mov eax, [eax]
lea eax, [edx+eax]
sub eax, 30h
mov [ebp+var_10], eax
add [ebp+input], 4
call ___ctype_b_loc
mov edx, [eax]
mov eax, [ebp+input]
mov eax, [eax]
add eax, eax
lea eax, [edx+eax]
movzx eax, word ptr [eax]
movzx eax, ax
and eax, 800h
test eax, eax
jnz short loc_8048451
cmp [ebp+var_9], 2Dh
jnz short loc_804849A
neg [ebp+var_10]
loc_804849A:
mov eax, [ebp+var_10]
leave
retn
_f endp
127