current->[fp-4]
last->[fp-8]
sum->[fp-12]

x->[fp+68]

_fib:
	save sp,-112,sp
	st R0,[fp+68]
	mov 1,R0
	st R0,[fp-4]
	st R0,[fp-8]
	st R0,[fp-12]
	ld [fp+68],R0
	sub R0,2,R0
	st R0,[fp+68]
cond:
	ld [fp+68],R0
	mov 0,R1
	cmp R0,R1
	ble body
	b exit
body:
	ld [fp-4],R0
	ld [fp-8],R1
	add R0,R1,R0
	st R0,[fp-12]
	ld [fp-4],R0
	st R0,[fp-8]
	ld [fp-12],R0
	st R0,[fp-4]
	ld [fp+68],R0
	sub R0,1,R0
	st R0,[fp+68]
	b cond
exit:
	ld [fp-12],R0
	restore
	ret