.data
str:	.space	33
foo:	.word	12
	
	.text
main:	# READ STRING FROM USER
	li	$v0,8
	la	$a0,str
	li	$a1,33
	syscall


	# INITIALIZE BITMASK, VAL
	li	$s0,0		# bitmask
	li	$s1,0		# val
	li	$s2,0		# counter
la	$s3,str	# pointer to current character in string
la	$a0,str	# set up str argument, which is constant

# BEGIN RECURSION LOOP
loop:	lb	$t0,0($s3)	# load character from string
	beq	$t0,0,exit	# check for null termination in string
	move	$a2,$t0	# set up val argument
	li	$t0,1		# maneuver a 1 bit into position i in bitmask
	sllv	$t0,$t0,$s2
	move	$a1,$t0	# copy bitmask argument
	li	$a3,1		# set up depth argument
	jal 	scramble
	addi	$s2,$s2,1	# increment counter
	addi	$s3,$s3,1	# increment str pointer
	j	loop



exit:



scramble:
	# save arguments on the stack
	addi	$sp,$sp,-28
	sw	$a0,0($sp)
	sw	$a1,4($sp)
	sw	$a2,8($sp)
	sw	$a3,12($sp)
	sw	$ra,16($sp)
	sw	$s2,20($sp)
	sw	$s3,24($sp)


	bne	$a3,4,recurse
	# print val as string

# print byte 0 of val
	li	$v0,11
	move	$t0,$a2
	andi	$a0,$t0,0x000000FF	# mask off byte 0
	syscall

# print byte 1 of val
move	$t0,$a2
	srl	$t0,$t0,8
	li	$v0,11
	andi	$a0,$t0,0x000000FF	# mask off byte 0
	syscall

# print byte 2 of val
move	$t0,$a2
	srl	$t0,$t0,16
	li	$v0,11
	andi	$a0,$t0,0x000000FF	# mask off byte 0
	syscall

# print byte 3 of val
move	$t0,$a2
	srl	$t0,$t0,24
	li	$v0,11
	andi	$a0,$t0,0x000000FF	# mask off byte 0
	syscall

	j return

recurse:
	
	# INITIALIZE BITMASK, VAL
	li	$s2,0		# counter
move	$s3,$a0	# pointer to current character in string



# BEGIN RECURSION LOOP
loop2:	lb	$t0,0($s3)	# load character from string
	beq	$t0,0,return	# check for null termination in string

	# insert character into val ($a2)
	sll	$t1,$a3,3		# $t1 = depth * 8
	sllv	$t0,$t0,$t1	# shift my character into position
	or	$a2,$a2,$t0	# insert new character	

	# set bit i in bitmask ($a1)
	li	$t0,1		# maneuver a 1 bit into position i in bitmask
	sllv	$t0,$t0,$s2
	or	$a1,$a1,$t0 #set bit i in bitmask ($a1)

	# add one to depth
	addi	$a3,$a3,1
	jal 	scramble
	# substract one from  depth
	addi	$a3,$a3,-1
	
	li	$t2,0xFF		# establish a character bitmask
	sllv	$t2,$t2,$t1	# shift bitmask under byte depth
	nor	$t2,$t2,$0		# complement bitmask
	and	$a2,$a2,$t2	# delete old character

	# set bit i in bitmask ($a1)
	li	$t0,1		# maneuver a 1 bit into position i in bitmask
	sllv	$t0,$t0,$s2
	xor	$a1,$a1,$t0 #set bit i in bitmask ($a1)

	addi	$s2,$s2,1	# increment counter
	addi	$s3,$s3,1	# increment str pointer
	j	loop2
	
	

return:
	# pop stack and return
	lw	$a0,0($sp)
	lw	$a1,4($sp)
lw	$a2,8($sp)
lw	$a3,12($sp) 
lw	$ra,16($sp)
lw	$s2,20($sp)
lw	$s3,24($sp)
addi	$sp,$sp,28
	jr	$ra