fib:
    addi $sp,$sp,-12 #create stack for 2 words
    slti $t0,$a0,1 #n<1
    beq $t0,1,ret #we return value
    beq $a0,1,ret #we ret value as n==1

    #store the ra
    sw $ra,8($sp)
    sw $a0,0($sp) #first element will be the argument passed to fib, that is n
    addi $a0,$a0,-1 #compute n-1 and call fib
    jal fib

    #restore back value
    lw $a0,0($sp)
    #now store the result
    sw $v0,4($sp)

    #now compute n-2 and call fib
    addi $a0,$a0,-2
    jal fib

    #now return fib(n-1)+fib(n-2)
    lw $t0,4($sp) #restore fib(n-1) value
    add $v0,$v0,$t0
    lw $ra,8($sp)
    #now just pop last 3 elements of stack
    addi $sp, $sp, 12


    jr $ra #jump to return addr


ret:

    add $v0,$a0,$zero #just return n as it was <=1
    jr $ra