strcpy.s

		B	test_strcpy

tsc_string	DEFB	"Hello World",0
tsc_dest	DEFB	"###########################",0
tsc_copied	DEFB	"Copied '",0
tsc_to		DEFB	"' to '",0
tsc_eol		DEFB	"'\n",0
		ALIGN

;; Test initial implementation
test_strcpy
		MOV		R13,#0x10000

		ADRL	R0,tsc_dest
		ADRL	R1,tsc_string
		BL		strcpy

		ADRL	R0,tsc_copied
		SWI		3

		ADRL	R0,tsc_string
		SWI		3

		ADRL	R0,tsc_to
		SWI		3

		ADRL	R0,tsc_dest
		SWI		3

		ADRL	R0,tsc_eol
		SWI		3

		SWI		2


;; strcpy -- copy the string at R1 to the address at R0
;; R0 <--- destination
;; R1 <--- source

strcpy
	; load each byte sequentially then store at new address, incrementing
	; the address for each character, until zero byte at the end is 
	; reached (but still copied)

mainStrLoop
	LDRB R2, [R1], #1 ; post increment the value in R1 by 1
	STRB R2, [R0], #1

	; and if it's zero, quit	
	CMP R2, #0
	BEQ stopCopying 

	; else, continue
	B mainStrLoop



stopCopying
	; if the zero is hit, we BL back
	MOV PC, R14