//-----------------------------------------------------------------
//	xmastest.s
//
//	This is the skeleton-code for a program that can automate
//	the testing of our 'xmas' demo-program, if you finish it.
//	(Why do you think we've linked in our 'base10io.o' file?)
//
//	   to assemble:  $ as xmastest.s -o xmastest.o
//	   and to link:  $ ld xmastest.o base10io.o -o xmastest
//
//	programmer: ALLAN CRUSE
//	written on: 28 FEB 2007
//-----------------------------------------------------------------

	# manifest constants
	.equ	sys_FORK, 2
	.equ	sys_WAITPID, 7
	.equ	sys_EXECVE, 11 
	.equ	sys_EXIT, 1

	.section	.data
arg0:	.asciz	"xmas"		# null-terminated program-name
arg1:	.asciz	"2007"		# null-terminated cmd-line arg
argv:	.long	arg0, arg1, 0	# list of command-line strings

	.section	.text
_start:
	# here we need to enter a loop that will examine various years 
	# (it is left as an exercise for you to construct such a loop)	

	mov	$sys_FORK, %eax		# system-call ID-number
	int	$0x80			# invoke kernel service
	or	%eax, %eax		# process is the child?
	jz	child			# yes, execute 'xmas'

	mov	%eax, %ebx		# child's process ID
	mov	$sys_WAITPID, %eax	# system-call ID-number
	xor	%ecx, %ecx		# ignore return-status
	xor	%edx, %edx		# no special options
	int	$0x80			# invoke kernel service

	mov	$sys_EXIT, %eax		# system-call ID-number
	xor	%ebx, %ebx		# use zero as exit-code
	int	$0x80			# invoke kernel service
child:
	mov	$sys_EXECVE, %eax	# system-call ID-number
	lea	arg0, %ebx		# address of program-name
	lea	argv, %ecx		# address of arg-pointers
	xor	%edx, %edx		# no special environment
	int	$0x80			# invoke kernel service

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