loop-gas-1.s

.text
.globl    _start

start = 0                       /* starting value for the loop index; note that this is a symbol (constant), not a variable */
max = 10                        /* loop exits when the index hits this number (loop condition is i<max) */

_start:
    mov     $start,%r15         /* loop index */

loop:
    /* ... body of the loop ... do something useful here ... */


    /* Printing .msg */
    movq    $len,%rdx   /*Length of data in address pointed by msg*/
    movq    $msg,%rsi   /*Message data on msg*/
    movq    $1,%rdi     /*1 for stdout*/
    movq $1,%rax        /*sys_write instruction*/
    syscall

    /*following digit*/
    movq    $len2,%rdx  /*Length*/
    movq    $digit,%rsi /*Message data on digit (blank space)*/
    movb    %r15b,(%rsi)/*Moves loop counter as a byte to rsi (digit)*/
    add     $48,(%rsi)  /*ASCII conversion*/
    movq    $1,%rdi     /*stdout*/
    movq $1,%rax        /*sys_write*/
    syscall

    /*prints newline char*/
    movq    $len1,%rdx
    movq    $nl,%rsi
    movq    $1,%rdi
    movq    $1,%rax
    syscall

    inc     %r15                /* increment index */
    cmp     $max,%r15           /* see if we're done */
    jne     loop                /* loop if we're not */

    mov     $0,%rdi             /* exit status */
    mov     $60,%rax            /* syscall sys_exit */
    syscall

.section .data

msg:    .ascii " Loop: "
        len = . - msg

nl:     .ascii "\n"
        len1 = . - nl

digit:  .ascii " "
        len2 = . - digit