.text
sum:
	;r1 = len
	;r2 = arr
	;r3 = i
	;r0 = sum
	;r4 arr data
	ldis r0, 0
	addi r3, r1, 0
	retzs- ; check len != 0
loop:
	;load arr data
	ldw r4, 0(r2)
	;sum += arr[i];
	add r0, r0, r4
	addi r2, r2, 4
	subi r3, r3, 1
	brnz+ loop
	ret