section .data
str:    db "This is my ", 0
stt:    db "test string", 0


section .text
global _start
    _start: ;just a way to test functions
    mov eax, str
    call    _print
    mov eax, stt
    call    _println
    call    _exit


    _exit: ;clean program exit
    mov eax, 1
    mov ebx, 0
    int 80h


    _strlen: ;takes a string from the 'eax' register and returns the length of it in 'eax'
    push    ebx
    mov ebx, eax
    __strlen:
    cmp byte [ebx], 0
    jz  ___strlen
    inc ebx
    jmp __strlen
    ___strlen:
    sub ebx, eax
    mov eax, ebx
    pop ebx
    ret


    _print: ;takes a string from the 'eax' register and prints to stdout
    push    eax
    push    ebx
    push    ecx
    push    edx
    mov ecx, eax
    call    _strlen
    mov ebx, eax
    mov edx, ebx
    mov ebx, 1
    mov eax, 4
    int 80h
    pop edx
    pop ecx
    pop ebx
    pop eax
    ret


    _println: ;; print with newline
    call    _print
    push    eax
    mov eax, 0ah
    push    eax
    mov eax, esp
    call    _print
    pop eax
    pop eax
    ret