//-----------------------------------------------------------------
//	linuxapp.s
//
//	This is a simple Linux application-program, written in the
//	GNU assembly language, for execution by an ia32 processor. 
//
//	  to assemble:  $ as --32 linuxapp.s -o linuxapp.o
//	  and to link:  $ ld -melf_i386 linuxapp.o -o linuxapp
//	  and execute:  $ ./linuxapp
//
//	NOTE: Our classroom systems now produce x86_64 executables
//	by default, unless we override with command-line switches.
//
//	programmer: ALLAN CRUSE
//	written on: 15 OCT 2008
//-----------------------------------------------------------------


	# manifest constants
	.equ	sys_EXIT, 1		# ID-number for 'exit'
	.equ	sys_WRITE, 4		# ID-number for 'write'
	.equ	dev_STDOUT, 1		# ID-number for STDOUT


	.section	.data
msg:	.ascii	"\n Hello, world! \n\n"	# contents of message
len:	.int	. - msg			# count of characters


	.section	.text
_start:	
	# display message
	mov	$sys_WRITE, %eax	# system-call ID-number
	mov	$dev_STDOUT, %ebx	# device-file ID-number
	lea	msg, %ecx		# address of the string
	mov	len, %edx		# length of the message
	int	$0x80			# invoke kernel service

	# terminate application
	mov	$sys_EXIT, %eax		# system-call ID-number
	mov	$0, %ebx		# program's exit-status
	int	$0x80			# invoke kernel service

	.global	_start			# make entry-point visible
	.end				# nothing more to assemble