# The following data go into the data segment
.data

string1: .asciiz "Inserisci un array di interi positivi (max 100 numeri, 0 per terminare).\n"
string2: .asciiz "Dammi un intero: "
string3: .asciiz "Il risultato è: "
.align 2
array: .space 400	# array with 100 elements

# Here begins the text (code) segment
.text

main:

	# Ask for the array
	li $v0, 4		# Select print_string
	la $a0, string1	# $a0 contains the address of string1
	syscall			# launch print_string
	
	# Prepare for reading
	add $s0, $zero, $zero	# $s0 = 0
	la $t1, array			# Base address of array in $t1
	
	# Read the array (while)
while:
	
	# Ask for the number
	li $v0, 4			# Select print_string
	la $a0, string2		# $a0 contains the address of string2
	syscall				# launch print_string
	
	#Read int
	li $v0, 5			# Select read_int
	syscall				# launch read_int (read int in $v0) 
	add $t0, $v0, $zero	# $t0 = $v0
	
	# Break for $t0=0
	beq $t0, $zero, endwhile	# if $t0==0, break
	
	# Add element to array
	sw $t0, 0($t1)		# array[$s0] = $t0
	addi $t1, $t1, 4	# Memory address of the next element
	addi $s0, $s0, 1	# $s0 = $s0+1, array index
	
	# While
	j while				# jump to while
	
endwhile:

	# Call the sumArray procedure
	la $a0, array		# $a0 = base address of array
	add $a1, $zero, $s0	# $a1 = number of elements of the array
	jal	sumArray		# Call sumArray
	move $t2, $v0		# $t2 = $v0 = sum of array
	
	# Show result
	li $v0, 4			# Select print_string
	la $a0, string3		# $a0 contains the address of string3
	syscall				# launch print_string
	li $v0, 1			# Select print_int
	move $a0, $t2		# $a0 = $t2
	syscall				# launch print int
	
	# Exit
	li $v0, 10		# Select exit
	syscall			# Exit
	
# ------------------------------------
# Procedures

# Procedure sumArray
# Input : $a0 -> base addred of the array of integers
# Input : $a1 -> number of elements of the array
# Output: $v0 -> sum of the elements of the array
sumArray:

	# Prepare for sum
	addi $t0, $zero, 0		# $t0 = 0	
	add $t1, $zero, $a1		# $t1 = number of elements of the array
	add $t2, $zero, $a0		# $t2 = base address
	
	# Do sum (for)
for:

	# Load value from memory, add to sum
	lw $t3, 0($t2)			# $t3 = array[index]
	add $t0, $t0, $t3		# $t0 = Sum = Sum + array[index]
	
	# Decrease the number of elements, increase the address
	addi $t2, $t2, 4		# $t2 = $t2 + 4 -> index++
	addi $t1, $t1, -1		# St1--
	
	# for?
	bne $t1, $zero, for		# Return to for
	
	# Prepare output
	move $v0, $t0			# $v0 = $t0 = Sum of array
	
	# Return
	jr $ra					# Return to return address