asm

; Simple example demonstrating basic program format and layout.
; Ed Jorgensen
; July 18, 2014
; ************************************************************
; Some basic data declarations
section .data
; -----
; Define constants
EXIT_SUCCESS equ 0 ; successful operation
SYS_exit equ 60 ; call code for terminate
; -----
; Byte (8-bit) variable declarations
bVar1 db 17
bVar2 db 9
bResult db 0
; -----
; Word (16-bit) variable declarations
wVar1 dw 17000
wVar2 dw 9000
wResult dw 0
; -----
; Double-word (32-bit) variable declarations
dVar1 dd 17000000
dVar2 dd 9000000
dResult dd 0
; -----
; Quad-word (64-bit) variable declarations
qVar1 dq 170000000
qVar2 dq 90000000
qResult dq 0
; ************************************************************
; Code Section
section .text
global _start
_start:
; Performs a series of very basic addition operations
; to demonstrate basic program format.
; ----------
; Byte example
; bResult = bVar1 + bVar2
 mov al, byte [bVar1]
 add al, byte [bVar2]
 mov byte [bResult], al
; ----------
; Word example
; wResult = wVar1 + wVar2
 mov ax, word [wVar1]
 add ax, word [wVar2]
 mov word [wResult], ax
; ----------
; Double-word example
; dResult = dVar1 + dVar2
 mov eax, dword [dVar1]
 add eax, dword [dVar2]
 mov dword [dResult], eax
; ----------
; Quad-word example
; qResult = qVar1 + qVar2
 mov rax, qword [qVar1]
 add rax, qword [qVar2]
 mov qword [qResult], rax
; ************************************************************
; Done, terminate program.
last:
 mov rax, SYS_exit ; Call code for exit
 mov rdi, EXIT_SUCCESS ; Exit program with success
 syscall