//-----------------------------------------------------------------
//	linkdemo.s
//
//	This program shows how an application in assembly language 
//	can call an 'external' subroutine (defined in a separately 
//	assembled file, then 'linked' to this application's code). 
//
//	  assemble using: $ as linkdemo.s -o linkdemo.o
//	  then link with: $ ld linkdemo.o dumpregs.o -o linkdemo
//
//	programmer: ALLAN CRUSE
//	written on: 13 FEB 2008
//-----------------------------------------------------------------


	.equ	sys_exit, 1		# system-call ID-number
	.equ	sys_write, 4		# system-call ID-number
	.equ	dev_stdout, 1		# device-file ID-number



	.section	.data
msg:	.ascii	"\nCurrent values in CPU registers: \n"
len:	.int	. - msg


	.section	.text
_start:
	# show our title message

	mov	$sys_write, %eax
	mov	$dev_stdout, %ebx
	mov	$msg, %ecx
	mov	len, %edx
	int	$0x80

	# setup some easy-to-recognize values in CPU registers

	mov	$0xAAAAAAAA, %eax
	mov	$0xBBBBBBBB, %ebx
	mov	$0xCCCCCCCC, %ecx
	mov	$0xDDDDDDDD, %edx
	mov	$0x01234567, %esi
	mov	$0x89ABCDEF, %edi
	
	# now call our external 'dumpregs' procedure

	call	dumpregs

	# now terminate this application 

	mov	$sys_exit, %eax
	mov	$0, %ebx
	int	$0x80

	.global	_start
	.end