//
//  Illustrate allocating some unused registers as local variables of function
//
//
//

/* --------------------------------------------------
   Define required labels for EGTAPI
   -------------------------------------------------- */
        .global main, Stop, CodeEnd, DataStart, DataEnd

	.global Pause, sumRange

/* --------------------------------------------------
   Begin of the program instructions
   -------------------------------------------------- */
	.text
main:
	// sum = sumRange(A, x, y)

	// pass A in r0
	movw  r0, #:lower16:A
	movt  r0, #:upper16:A

	// pass x in r1
        movw  r1, #:lower16:x
        movt  r1, #:upper16:x
	ldr   r1, [r1]

	// pass y in r2
        movw  r2, #:lower16:y
        movt  r2, #:upper16:y
        ldr   r2, [r2]

	bl sumRange

        movw  r1, #:lower16:sum
        movt  r1, #:upper16:sum
	str   r0, [r1]

Pause:
	// sum = sumRange(B, 3, 7)

	movw  r0, #:lower16:B
        movt  r0, #:upper16:B

	mov   r1, #3
	mov   r2, #7

        bl sumRange

        movw  r1, #:lower16:sum
        movt  r1, #:upper16:sum
        str   r0, [r1]




Stop:
	nop			   // Stop point of main( )


sumRange:
	// A=r0, a=r1, b=r2, i=r3, s=r4

	mov  r4, #0	// s = 0
	mov  r3, r1	// i = a

while:
	cmp  r3, r2
	bge  whileEnd

	add  r5, r3, r3	// r5 = 2*i
	add  r5, r5, r5 // r5 = 4*i

	ldr  r5, [r0, r5] // r5 = A[i]

	add  r4, r4, r5   // s = s + A[i]

	add  r3, r3, #1   // i++
	b    while

whileEnd:
	// return(s)

	mov  r0, r4
	mov  pc, lr

CodeEnd:
    	nop

/* --------------------------------------------------
   Begin of the permanent program variables
   -------------------------------------------------- */
	.data
DataStart:

A:	.4byte	11, 12, 13, 14, 15, 16, 17, 18, 19 , 20
B:	.4byte	1, 2, 3, 4, 5, 6, 7, 8, 9, 10
x:	.4byte	1
y:	.4byte	3
sum:	.4byte  -1

DataEnd:

	.end