fibonacciMips2.asm

.data
	input: .asciiz "enter your number"
	
.text
	.globl main
	main:
	li $v0 , 4
	la $a0 , input
	syscall
	
	li $v0 , 5
	syscall 
		
	#a0 -> argument 
	#t0 -> placeholder 0
	#t1 -> placeholder 1
	#t2 -> iterator
	#t3 -> temp
	#v1 -> result
	fib:
	#placeholders initialization
	addi $t0 , $zero , 0
	addi $t1 , $zero , 1
	#iterator init
	addi $t2 , $zero , 1		#starting iterator from 1 because it will do fib repeatitions n-1 times
					#it will do fib repeatitions n-1 times as follows
					#fib(5) :
					#	fib(0) = 0 	_
					#			 |
					#			 |->	given
					#			_|
					# 	fib(1) = 1	
					#
					#	fib (2) = fib(1) + fib(0)	#1
					#		=   0    +   1	 ....fib(2) recorded in placeholder 2
					#	fib (3) = fib(2) + fib(1)	#2
					#		=   1    +   1   ....fib(3) recorded in placeholder 2
					#	fib (4) = fib(3) + fib(2)	#3
					#		=   2    +   1   ....fib(4) recorded in placeholder 2
					#	fib (5) = fib(4) + fib(3)	#4
					#		=   3    +   2   ....fib(5) recorded in placeholder 2	
					# and thus, fib(5) = 5 			Q.E.D		
	bgt $a0 , $zero , inputIsGreaterThanZero
	addi $v0 , $zero ,0 
	
	inputIsGreaterThanZero: bgt $a0 , $t1 , loop 
	addi $v0 , $zero ,1
	
	loop:
	bge $t2 , $v0 , done
	addi $t3 , $t0 , 0
	addi $t0 , $t1 , 0
	add  $t1 , $t3 , $t1 
	addi $t2 , $t2 , 1
	j loop
	done:
	addi $v1 , $t1 , 0
	
	
	addi $a0 , $v1 , 0
	li $v0 , 1
	syscall