.text
	.global main	
@******************************************************************
        .equ    NUL, 0          @ NUL is used for end of string
strcopy:                        @ Entry to "strcopy" function
                                @ R0 = address of destination string
                                @ R1 = address of source string
l1:
        ldrb    r2,[r1],#1      @ Load byte into R2 and update R1
        strb    r2,[r0],#1      @ Store the byte and update R0
        cmp     r2,#NUL         @ Check for NUL terminator
        bne     l1              @ Repeat loop if not
	bx lr
@*******************************************************************
main:
	push {lr}
	ldr	r0,=str_before	@ Print str_before to the console
	bl 	puts
	ldr	r0,=srcstr
	bl	puts
	ldr	r0, =dststr
	bl	puts
	ldr	r0,=dststr	@ R0 := address of destination string
	ldr	r1,=srcstr	@ R1 := address of source string
	bl	strcopy		@ Call the function "strcopy" (in "copy.s")
	ldr	r0,=str_after	@ Print str_after to the console
	bl	puts		@ then print the two strings (again)
	ldr	r0,=srcstr
	bl	puts
	ldr	r0, =dststr
	bl	puts
	pop {pc}
	.data			@ Read/write data follows
	.align			@ Align to a 32-bit boundary
srcstr:	.asciz	"First (source) string"
dststr:	.asciz	"Second (destination) string"
str_before:
	.asciz	"Before copying:"	@ Note: NOT ".asciz"!
str_after:
	.asciz	"After copying:"	@ The same, using C-style escapes
	.end