# merge.s -- Merge 2 sorted lists into one.  The data are doubles.
# Let's assume each list ends with the number 0.0.
# $s1 = base address of list 1
# $s2 = base address of list 2
# $s3 = base address of list 3
# $s4 = base address of arbitrary list for print_list function
# $t1 = total address of list 1
# $t2 = total address of list 2
# $t3 = total address of list 3
# $t4 = total address of arbitrary list for print_list function
# $f20 = sentinel value indicating end of a list (set to 0.0)
# $f22 = value from list 1
# $f24 = value from list 2

#--------------------------------------------------------------------
	.data
sentinel:	.double 0.0
list1:	.double  7.2  9.5  10.3  15.6  18.1  20.9  22.6  23.3  27.5  30.1  0.0
list2:	.double  6.7  8.3   8.8  16.9  17.7  19.4  21.2  22.9  33.7  36.2  0.0
list3:	.space 800	# make room for 100 doubles -- more than enough
moving_str:		.asciiz " is being moved into list 3.\n"
announce_list1:		.asciiz "Here is list 1:\n"
announce_list2:		.asciiz "Here is list 2:\n"
announce_list3:		.asciiz "Here is list 3:\n"
newline:		.asciiz "\n"
#--------------------------------------------------------------------
	.text
main:
	la $gp, sentinel	# initialize $f20 to the value 0.0
	l.d $f20, 0($gp)

	la $s1, list1		# set base addresses of all 3 lists
	la $s2, list2
	la $s3, list3

	#-------------------------------------
	# Begin by showing user lists 1 and 2.
	#-------------------------------------

	li $v0, 4		# introduce list 1
	la $a0, announce_list1
	syscall

	move $s4, $s1		# pass base address of list 1 for printing
	jal print_list		# print list 1

	li $v0, 4		# introduce list 2
	la $a0, announce_list2
	syscall

	move $s4, $s2		# pass base address of list 2 for printing
	jal print_list

	#---------------------------------------------------
	# Now, time to merge the lists together into list 3.
	#---------------------------------------------------

	move $t1, $s1		# initialize total address to start at base
	move $t2, $s2
	move $t3, $s3
loop:
	l.d $f22, 0($t1)	# get number from list 1
	l.d $f24, 0($t2)	# get number from list 2

	#-----------------------------------------------------------
	# ALGORITHM TO PERFORM MERGE:
	#
	# if the number from list 1 is the sentinel end value,
	#    empty the rest of list 2 into list 3
	# else if the number from list 2 is the sentinel end value,
	#    empty the rest of list 1 into list 3
	# else if the number from list 1 is smaller,
	#    put it in list 3 and get next number from list 1
	# else if the number from list 2 is smaller,
	#    put it in list 3 and get next number from list 2
	#----------------------------------------------------------


	#---------------------------------
	# Here we empty list 2 into list 3
	#---------------------------------


	#---------------------------------
	# Here we empty list 1 into list 3
	#---------------------------------


	#--------------------------------------------------------------
	# Here we copy the element from list 1 to list 3, and continue.
	#--------------------------------------------------------------


	#--------------------------------------------------------------
	# Here we copy the element from list 2 to list 3, and continue.
	#--------------------------------------------------------------


	#----------------------------------
	# Now we are ready to print list 3.
	#----------------------------------

after_loop:
	li $v0, 4		# introduce output
	la $a0, announce_list3
	syscall

	move $s4, $s3
	jal print_list

	li $v0, 10		# end of program
	syscall

#---------------------------------------------------------------------
# notify_move function:  Tell the user what number is being put into
# list 3.  We assume that the number to print is already in $f12.
notify_move:
	li $v0, 3		# print what number is being moved
	syscall

	li $v0, 4
	la $a0, moving_str
	syscall

	jr $ra
#---------------------------------------------------------------------
# empty list function
# $f26 = element loaded from either list 1 or list 2
# $t4 = address where we begin to load elements from
empty_list:
	sw $ra, 0($sp)		# save return address
	addi $sp, $sp, -4

	l.d $f26, 0($t4)

	c.eq.d $f26, $f20	# is there nothing left in list?
	bc1t after_loop

empty_list_loop:
	mov.d $f12, $f26	# tell user we're moving which element
	jal notify_move

	s.d $f26, 0($t3)	# put list 1 (or list 2) element into list 3
	addi $t4, $t4, 8	# point to next element
	addi $t3, $t3, 8	
	
	l.d $f26, 0($t4)	# get next element --> $f26
	c.eq.d $f26, $f20
	bc1f empty_list_loop

	addi $sp, $sp, 4	# restore return address
	lw $ra, 0($sp)

	jr $ra
#--------------------------------------------------------------------
# print list function
# Since all we're really doing with the floating-point numbers
# in the list is printing them, let's just load each one into $f12.
print_list:

	#-----------------------------------------
	# Add code here to implement the function.
	#-----------------------------------------

	jr $ra