; ***********************************************************************
; *									*
; *         User Mode Code for the Flash Program, First Version         *
; *									*
; ***********************************************************************

; Author:   John Zaitseff <J.Zaitseff@unsw.edu.au>
; Date:     28th May, 2003
; Version:  1.2

; This file contains the main program for the first version of Flash, as
; used in ELEC2041 Experiment 5.  This code runs in User mode.  The main
; feature of this program is that it uses an SWI instruction to set the
; LEDs on and off.


	.text			; Ordinary program code follows

	.include "header-v1.s"	; Include various definitions

	.global main		; Make this label visible to other modules


; -----------------------------------------------------------------------
; The main program, running in User mode.  Notice that the main program
; assumes it has intimate knowledge of how the SWI handler works: it
; assumes that R0 is NOT modified by the SWI handler.  Doing this sort of
; thing is generally considered a bad programming practice!

main:				; Main program, running in User mode
	ldr	r0, =portA	; Load address of Port A into R0

main_loop:
	mov	r1, #value1	; R1 = value to turn the LEDs on
	swi			; Generate a software interrupt

	mov	r1, #value2	; R1 = value to turn the LEDs off
	swi			; Generate a software interrupt

	b	main_loop	; Repeat forever (or until stopped)

	.end