Assembly Language Programming (intel 32 bit) under Unix.

A. Slightly easier way

  1. Make a library of functions so that you don't have to deal with stdio

    $ cat ass.c

    #include <stdio.h>

    void printi(int n) { printf("%d", n); }
    void prints(char * s) { printf("%s", s); }
    void printc(char c) { printf("%c", c); }
    int readi(void) { int n; scanf("%d", & n); return n; }

    $ cc -c ass.c

  2. Here is a complete assembly language file, with its own main, that uses
     that library

    $ cat assex.s
            .file   "assex.s"
            .text

            .p2align 2,,3
    .globl semblyfn
            .type   semblyfn, @function
    semblyfn:
            pushl   %ebp
            movl    %esp, %ebp
            subl    $4, %esp
            movl    8(%ebp), %eax
            addl    12(%ebp), %eax
            movl    %eax, -4(%ebp)
            pushl   %eax
            call    printi
            addl    $4, %esp
            pushl   $10
            call    printc
            addl    $4, %esp
            movl    -4(%ebp), %eax
            incl    %eax
            addl    $8, %esp
            leave
            ret
            .size   semblyfn, .-semblyfn
   
            .p2align 2,,3
    .globl main
            .type   main, @function
    main:
            pushl   %ebp
            movl    %esp, %ebp
            pushl   $123
            pushl   $101          
            call    semblyfn
            addl    $8, %esp
            movl    $0, %eax
            leave             
            ret             
            .size   main, .-main

    $ cc assex.s ass.o

    $ a.out

    224

B. Just stand-alone assembly

  $ cat examp.s

        .file   "examp.s"

        .section        .rodata
  .format1:
        .string "%d + %d is %d\n"

        .text
        .p2align 2,,3
  .globl main
        .type   main, @function
  main:
        pushl   %ebp
        movl    %esp, %ebp
        subl    $8, %esp
        movl    $123, %eax
        movl    %eax, -4(%ebp)
        movl    $202, %eax
        movl    %eax, -8(%ebp)
        movl    -4(%ebp), %eax
        addl    -8(%ebp), %eax
        pushl   %eax
        pushl   -8(%ebp)
        pushl   -4(%ebp)
        pushl   $.format1
        call    printf
        addl    $12, %esp
        movl    $0, %eax
        addl    $8, %esp
        leave
        ret
        .size   main, .-main

  $ cc examp.s

  $ a.out

  123 + 202 is 325