; Returns:
; rax - if line: line length; otherwise: 0
; Arguments:
; rdi - buffer
; rsi - max length
scanline:
    mov rax, 0

scanline__loop:
    cmp rax, rsi
    jge scanline__incomplete_line
    mov r10b, [rdi + rax]
    add rax, 1
    cmp r10b, 0x0a  ; '\n'
    jne scanline__loop
    ret

scanline__incomplete_line:
    mov rax, 0
    ret