.data				; data section

output:
    .ascii  "\n Fibonacci number is:  \0"
    len = .- output		; length of ascii output string

.text				; code section

    .globl _fibonacci
_fibonacci:
        li      r3, 14		; put number of loops   ( num loops +2 is fib num position )
        li      r7, 1		; put 1 into register 7 ( prime loop first fib number )
        li      r8, 1		; put 1 into register 8 ( prime loop second fib number )
	
fib_loop:
        add     r11, r7, r8     ; add the values in registers r7, r8 and store in r11
        mr      r7, r8		; move r8's value to r7 ( shift numbers for next loop )
        mr      r8, r11		; move r11's value to r8 ( set up for next loop )
        subi    r3, r3, 1       ; r3--  ( decrement loop counter )
        cmpwi   r3, 0           ; compare r3 with zero  ( are we done with loop? )
        bgt     fib_loop	; if r3 greater than 0 repeat fib_loop


# dump output  

	li      r0, 4		; syscall number ( system write )
	li      r3, 1		; first arg stdout
	lis     r4, ha16(output) ; first half of string
	addi    r4, r4, lo16(output) ; second half of string
	li      r5, len		; message length
	sc			; call kernel
	
# return fib number
	xor.    r3, r3, r3      ; zero out register 3
	mr      r3, r11
	
#exit
    blr				;branch to instruction register ( exit )