.data
SumOfN:	.word 	
	
	.text
	
Start:
	li $t2, 6     #going to compute the sum of n=6
	
	
	sw $a0, ($sp)  #store old a0 value so we don't loose it
	addi $sp, $sp, -4  #dec stack pointer
	sw $fp , -4($sp) #store the contents of the fp on the stack
	move $fp, $sp   #fp points to proper place in AR
	addi $sp,$sp,-8 #adjust sp to point to next free space on stack
	 
	move $a0, $t2  #load parameter register with n
	jal SumN_0	#call Sum of N procedure
	sw $v0, SumOfN  #Store the return value somewhere
	
	lw $a0, 4($fp)  #restore a0 which we saved on the stack
	move $fp, $sp	#wipe out the AR by setting sp=fp
	addi $sp, $sp, 4 #adjust sp to top of previous AR
	lw $fp, -4($fp)  #set fp to previous AR base
	
	
	
	
	
	lw $a0, SumOfN  #Print result to show it works
	li $v0, 1
	syscall
	
	li $v0, 10
	syscall 		

#Sum of N procedure
SumN_0: 
        sw $ra, ($fp)     	#store return address in AR 
	sw $s1, 0($sp)          #we are using the s registers
	sw $s2, -4($sp)		#so we must save them
	addi $sp, $sp, -8       # adjust sp
	
	
	move $s1, $a0
	move $s2, $s1
	sub $s1,$s1,1
SumN_1:	beqz $s1, SumN_3
	add $s2, $s2, $s1
	sub $s1, $s1, 1
	b SumN_1				
SumN_3: move $v0,$s2
	
	
	lw $s1, 8($sp)
	lw $s2, 4($sp)
	addi $sp, $sp, 8
	lw $ra, 0($fp)
	jr $ra