; ***********************************************************************
; *									*
; *                       Copy an Array of Words                        *
; *									*
; ***********************************************************************

; Author:   John Zaitseff <J.Zaitseff@unsw.edu.au>
; Date:     9th September, 2002
; Version:  1.3

; This program is, in the main, a demonstration of the ARM "ldr" and "str"
; instructions.  Do pay attention, however, at the use of the ".data"
; section, which contains read/write data.


	.text
	.global	_start

	.equ	num, 20		; Number of words to be copied

_start:
	ldr     r0,=src		; R0 = pointer to source block
	ldr     r1,=dst		; R1 = pointer to destination block
	mov     r2,#num		; R2 = number of words to copy

loop:
	ldr	r3,[r0],#4	; Load a word into R3 and update R0
				; (post-indexed: R0 := R0 + 4)
	str	r3,[r1],#4	; Store the word and update R1
	subs	r2,r2,#1	; Decrement the word counter
	bne	loop		; and repeat loop if not finished

exit:	swi	0x11


	.data			; Read/write data follows
	.align			; Make sure data is aligned on 32-bit
				; boundaries

src:	.word	 1,  2,  3,  4,  5,  6,  7,  8,  9, 10
	.word	11, 12, 13, 14, 15, 16, 17, 18, 19, 20

; The ".data" section can contain pre-initialised variables, as shown
; above

dst:	.word	 0,  0,  0,  0,  0,  0,  0,  0,  0,  0
	.word	 0,  0,  0,  0,  0,  0,  0,  0,  0,  0

; An alternative to directly including twenty "0"'s for the destination
; variable "dst" would be to use the ".skip" directive:
;
; dst:	.skip	num * 4		; Reserve 80 bytes (num 32-bit words)

	.end