; Hello.asm
; D. Thiebaut
;
; taken from http://untimedcode.com/2007/5/20/learn-nasm-assembly-on-mac-os-x
; Simple Hello World that runs on a Mac or on a Linux machine
;
; to assemble, link and run on a Mac:
;
; nasm -f macho hello.asm -DMAC
; ld -e _start -o hello hello.o
; ./hello
;
; to assemble, link and run on Linux:
;
; nasm -f elf -F stabs hello.asm
; ld -o hello hello.o
; ./hello
%macro int80 0
%ifdef MAC
push edx
push ecx
push ebx
push eax
%endif
int 0x80 ; call OSX call _syscall
%ifdef MAC
add esp, 16
%endif
%endm
;;; -------------------------------------------------
;;; data section
;;; -------------------------------------------------
section .data
msg db "Hello, World!",0xa ; string with a carriage-return
LEN equ $ - msg ; string length in bytes
;;; -------------------------------------------------
;;; code section
;;; -------------------------------------------------
section .text ; start of the code indicator
global _start ; make the main function externally visible
_start: ; entry point for linker
;;; write our string to standard output
mov eax, 0x4 ; system call for writing
mov ebx, 1 ; to stdout
mov ecx, msg ; the address of the string
mov edx, LEN ; the # of chars
int80
;;; exit
mov ebx, 0 ; exit code
mov eax, 0x1 ; system call number (sys_exit)
int80
