1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
|
!
! Dynamic Fibonacci Sequence Function
! Author: Dave Osborn
! Remarks: Program finds the Nth Fibonacci number in the sequence
! either by looking up the value in a table or by direct
! computation. If a computation is performed then the
! value is stored in a table for future reference.
!
.seg "text"
.global main
main:
mov 0x5,%o0 ! Load N
call dfib,1 ! dfib(N)
nop ! Fill delay slot
exit:
ret ! Finished
nop ! Fill delay slot
!
! Dynamic Fibonacci Function
! Register Usage:
! %i0 : Number of Ith sequence we are to find
! %l0 : %i0 - 1; Used for finding the offset into Array
! %l1 : Local Temporary
! %o0 : Copy of %i0, used to return value.
! %o1 : Base Address of Array
! %o2 : Offset into Array for element N
! %o3 : Value stored in Array[N]
!
dfib:
save %sp,-96,%sp ! Preserve Register Windows
mov %i0,%l0 ! Load N for manipulation
sub %l0,0x1,%l0 ! Array index is really an offset
! from 0.
set Array,%o1 ! Load address of Array
sll %l0,0x2,%o2 ! Find Offset into Array
ld [%o1+%o2],%o3 ! Load Value at Array[%o2]
tst %o3 ! Array[%o2] == 0??
be fib ! Yes, Compute Fibonacci
nop ! Fill Delay Slot
! Array[%o2] = a computed value, return the value in %o3
mov %o3,%o0
b finis
nop
fib:
cmp %i0,0x2 ! N <= 2?
bg recurse ! Nope, recurse
nop ! Fill delay slot
mov 0x1,%o0 ! fib = 1
b finis ! We're finished
nop ! fill delay slot
recurse:
sub %i0,0x2,%o0 ! N - 2
call dfib,1 ! dfib(N - 2)
nop ! Fill Delay Slot
mov %o0,%l1 ! Save Result for later
sub %i0,0x1,%o0 ! N - 1
call dfib,1 ! dfib(N - 1)
nop ! Fill Delay Slot
add %o0,%l1,%o0 ! dfib(N - 1) + dfib(N - 2)
st %o0,[%o1+%o2] ! Array[%o2] = %o0
finis:
mov %o0,%i0 ! return value
ret
restore
!
! Initialized Array of Data. Apparently as does not have a simple
! directive to setup a block of initialized memory so we have to
! specify our initialized data.
!
.seg "data"
.align 4
Array:
.word 0x1,0x1,0x0,0x0,0x0 ! Array[5] = {1, 1, 0, 0, 0}
|
