atoi

%include "io.inc"

section .data
    mystring db "-543", 0

section .text
global CMAIN
mul_10:
    push ebp
    mov ebp, esp
    mov ecx, [ebp + 8]
    shl ecx, 1
    mov ebx, ecx
    shl ecx, 2
    add ebx, ecx
    leave
    ret


atoi:
    push ebp
    mov ebp, esp
    cld
    mov esi, [ebp + 8]
    xor ebx, ebx
    xor eax, eax
    xor edx, edx

    lodsb
    cmp al, '-'
    jne not_negative
    mov edx, 1
add_digit:
    lodsb
    test al, al
    je end
not_negative:
    push ebx
    call mul_10
    add esp, 4
    add ebx, eax
    sub ebx, '0'
    ;PRINT_DEC 1, al
    jmp add_digit

end:
    cmp edx, 1
    PRINT_DEC 4, edx
    jne not_negative_end
    neg ebx
not_negative_end:
    NEWLINE
    PRINT_DEC 4, ebx
    leave
    ret

CMAIN:
    mov ebp, esp; for correct debugging

    push mystring
    call atoi
    pop eax

    mov ebp, esp
    xor eax, eax
    ret