#Program that converts a user's integer input between 0-65535 and converts it to Hex.
#Jacob Barrett

.data 						# Declares the Variables in the program

	# Array of the numbers in Hexidecimal form
	n0: .asciiz  "0"
	n1: .asciiz  "1"
	n2: .asciiz  "2"
	n3: .asciiz  "3"
	n4: .asciiz  "4"
	n5: .asciiz  "5"
	n6: .asciiz  "6"
	n7: .asciiz  "7"
	n8: .asciiz  "8"
	n9: .asciiz  "9"
	n10: .asciiz "A"
	n11: .asciiz "B"
	n12: .asciiz "C"
	n13: .asciiz "D"
	n14: .asciiz "E"
	n15: .asciiz "F"
	array1: .word n0,n1,n2,n3,n4,n5,n6,n7,n8,n9,n10,n11,n12,n13,n14,n15
	size: .space 64				# Size of the Array 4*16 = 64

	# Strings
	notInBetween: .asciiz "That wasn't a number between 0 and 65535."
	String: .asciiz "Enter a number between 0 and 65535: "
	Result: .asciiz "Your number in hex is: "


.text 						# Program's code after this line

.globl main

main:

	addi $t0, $zero, 0			# Counter that keeps track of how many times divideLoop is used

	li $v0, 4				# Asks the user to enter a number
	la $a0, String
	syscall

	li $v0, 5				# Reads the input by the user
	syscall
	addi $s0, $v0, 0			# Saves the input to $s0

	# Checks if the user's input is within 0-65535 for X
	blt $s0, 0, lessOrMoreThan		# If $s0 is less than 0, then go to lessOrMoreThan
	bgt $s0, 65536, lessOrMoreThan		# If $s0, is greater than 65536, then go to lessOrMoreThan

	j divideLoop				# Jump to divideLoop

divideLoop:
	blt $s0, 16, exit 			# Branches if $s0 is less than 16; it will branch to exit when it is done
	sub $s0, $s0, 16			# Subtracts X from 16, then stores the new value where X was. This is done
						# so that we can repetively subtract 16 from X in the loop; otherwise
						# it would keep subtracting 16 from X without updating X, creating an infinite loop

	add $t0, $t0, 1				# Counter for the number of times divideLoop is used (the quotient)
	j divideLoop

divideLoop2:
	blt $t0, 16, exit			# If $t0 is less than 16, then we no longer need to divide it. Go to exit
	sub $t0, $t0, 16			# Subtract 16 from $t0; this will be repeated until it is less than 16

	add $t1, $t1, 1
	j divideLoop2				# Counter for the number of times divideLoop2 is used (the quotient)

divideLoop3:
	blt $t1, 16, exit			# If $t1 is less than 16, then we no longer need to divide it. Go to exit
	sub $t1, $t1, 16			# Subtract 16 from $t1; this will be repeated until it is less than 16

	add $t2, $t2, 1				# Counter for the number of times divideLoop3 is used (the quotient)
	j divideLoop3


exit:

	# These are used to determine whether or not we need to divide more
	# If $t0 or $t1 is greater than 15, then it will throw an OutOfBound error
	bgt $t1, 15, divideLoop3		# Checks if $t1 is greater than 15; if it is, then go to divideLoop3
	bgt $t0, 15, divideLoop2		# Checks if $t0 is greater than 15; if it is, then go to divideLoop2


	move $s1, $t0				# Moves $t0 to $s1
	move $s2, $t1				# Moves $t1 to $s2
	move $s3, $t2				# Moves $t2 to $s3
	sll $s0, $s0, 2				# Sets $s0 * 4 ($s0 * 2^2)
	sll $s1, $s1, 2				# Sets $s1 * 4
	sll $s2, $s2, 2				# Sets $s2 * 4
	sll $s3, $s3, 2				# Sets $s3 * 4


### Print Result
	li $v0, 4				# Prints the result string
	la $a0, Result
	syscall
	li $v0, 4				# Prints out the first character for the Hex conversion (YXXX)
	lw $a0, array1($s3)
	syscall
	li $v0, 4				# Prints out the second character for the Hex conversion (XYXX)
	lw $a0, array1($s2)
	syscall
	li $v0, 4				# Prints out the third character for the Hex conversion (XXYX)
	lw $a0, array1($s1)
	syscall
	li $v0, 4				# Prints out the fourth character for the Hex converson (XXXY)
	lw $a0, array1($s0)
	syscall

	li $v0, 10				# Ends the program
	syscall

lessOrMoreThan:

	li $v0, 4				# Prints out the notInBetween string
	la $a0, notInBetween
	syscall


	li $v0, 10				# Ends the program
	syscall