;This program fills a block of memory with a fixed value and 
	;then transfers (copies) the block to new area of memory
	AREA	PROGRAM4_3, CODE, READONLY
	ENTRY
RAM1_ADDR	EQU	0x40000000	;Change the address for your ARM
RAM2_ADDR	EQU	0x40000100	;Change the address for your ARM
	BL	FILL		;call block fill subroutine
	BL	COPY		;call block transfer subroutine
HERE	BAL	HERE	;BAL(branch always) is the same as B	
	;----------------BLOCK FILL SUBROUTINE
FILL	LDR  	R1,=RAM1_ADDR	;R1 = RAM Address pointer
	MOV	R0,#10	 		;counter
	LDR	R2,=0x55555555
L1	STR	R2,[R1]			;send it to RAM
	ADD	R1,R1,#4		;R1 = R1 + 4 to increment pointer
	SUBS	R0,R0,#1		;R0 = R0 - 1 for dec counter 
	BNE	L1			;keep doing it
	BX	LR			;return to caller
	;-----------------BLOCK COPY SUBROUTINE
COPY	LDR	R1,=RAM1_ADDR	;R1 = RAM Address pointer (source)
	LDR	R2,=RAM2_ADDR	;R2 = RAM Address pointer  (dest.)
	MOV	R0,#10		;counter
L2	LDR	R3,[R1]		;get from RAM1
	STR	R3,[R2]		;send it to RAM2
	ADD	R1,R1,#4	;R1 = R1 + 4 to increment pointer for RAM1
	ADD	R2,R2,#4	;R2 = R2 + 4 to increment pointer for RAM2
	SUBS	R0,R0,#1	;R0 = R0 – 1 for decrementing counter 
	BNE	L2		;keep doing it
	BX	LR		;return to caller
	;----------	
	END			;notice the place of END directive