.global main

main: @start of program
	ldr r0, =welcome
	bl printf
	b prompt

prompt: @prints message that asks user to input a number (1-5)

	ldr r0, =decisionstring
	bl printf

	ldr r0, =intInputPattern
	ldr r1, =decisionNum
	bl scanf
	ldr r2, =decisionNum
	ldr r5, [r2]
	push {r5} @pushes decision integer onto stack
	b decision




decision: @subroutine that inputs numbers and branches to AND, ORR, EOR, or BIC based on user input
	pop {r10} @pops decision integer off of stack
	mov r1, r10
	ldr r0, =InputNumbers
	bl printf


	cmp r10, #1
	bleq inputHexNums
	temp5:bleq bitwiseAND

	cmp r10, #2
	bleq inputHexNums
	bleq bitwiseORR

	cmp r10, #3
	bleq inputHexNums
	bleq bitwiseEOR

	cmp r10, #4
	bleq inputHexNums
	bleq bitwiseBIC

	cmp r10, #5
	beq exit

	b prompt @else, exit

errorSubroutine:
	ldr r0, =error
	bl printf
	b inputNumber

inputNumber:
	push {lr}
	ldr r0, =hexInputPattern
	ldr r1, =hexNum1
	bl scanf
	ldr r2, =hexNum1
	ldr r1, [r2]
	cmp r1, #0
	beq errorSubroutine
	pop {lr}
	push {r1}
	mov r7, #1
	cmp r7, #1
	mov pc, lr


inputHexNums: @subroutine that inputs two hex numbers
	push {lr}
	bl inputNumber
	pop {r5}
	bl inputNumber
	pop {r6}
	pop {lr}
	temp1:push {r5}
	temp2:push {r6}
	mov pc, lr

bitwiseAND: @AND subroutine
	temp3:pop {r11}
	temp4:pop {r10}
	AND r12, r10, r11
	push {lr}
	ldr r0, =printnumber
	mov r1, r12
	bl printf
	pop {lr}
	mov pc, lr

bitwiseORR: @ORR subroutine
	pop {r11}
	pop {r10}
	ORR r12, r10, r11
	push {lr}
	ldr r0, =printnumber
	mov r1, r12
	bl printf
	pop {lr}
	mov pc, lr

bitwiseEOR: @EOR subroutine
	pop {r11}
	pop {r10}
	EOR r12, r10, r11
	push {lr}
	ldr r0, =printnumber
	mov r1, r12
	bl printf
	pop {lr}
	mov pc, lr

bitwiseBIC: @BIC subroutine
	pop {r11}
	pop {r10}
	BIC r12, r10, r11
	push {lr}
	ldr r0, =printnumber
	mov r1, r12
	bl printf
	pop {lr}
	mov pc, lr


exit: @subroutine to exit program
	mov r7, #0x01
	SVC 0


.data

.balign 4
hexInputPattern: .asciz "%x"

.balign 4
hexNum1: .word 0

.balign 4
hexNum2: .word 0


.balign 4
intInputPattern: .asciz "%d"

.balign 4
decisionNum: .word 0

.balign 4
InputNumbers: .asciz "Now input two hex numbers\n"

.balign 4
printnumber: .asciz "%x\n"

.balign 4
decisionstring: .asciz "Enter (1) for AND, (2) for ORR, (3) for EOR, (4) for BIC, and (5) to exit\n"

.balign 4
andstring: .asciz "You branched to AND\n"

.balign 4
orrstring: .asciz "You branched to ORR\n"

.balign 4
welcome: .asciz "Welcome to my binary calculator. This program can do 4 operations: AND, ORR, EOR, and BIC\n"

.balign 4
error: .asciz "Invalid input.. please input 2 new hex numbers\n"

.global scanf
.global printf