f4535c64 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id$ |
4 | * |
5 | * Exponentiation for large integers |
6 | * |
7 | * (c) 2004 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <assert.h> |
33 | |
34 | #include "mp.h" |
35 | #include "mp-exp.h" |
36 | |
37 | /*----- Main code ---------------------------------------------------------*/ |
38 | |
39 | /* --- @mp_exp@ --- * |
40 | * |
41 | * Arguments: @mp *d@ = fake destination |
42 | * @mp *a@ = base |
43 | * @mp *e@ = exponent |
44 | * |
45 | * Returns: Result, %$a^e$%. |
46 | */ |
47 | |
48 | mp *mp_exp(mp *d, mp *a, mp *e) |
49 | { |
50 | mp *x = MP_ONE; |
51 | mp *spare = (e->f & MP_BURN) ? MP_NEWSEC : MP_NEW; |
52 | assert(!MP_NEGP(e)); |
53 | |
54 | MP_COPY(a); |
55 | if (MP_ZEROP(e)) |
56 | ; |
57 | else if (MP_LEN(e) < EXP_THRESH) |
58 | EXP_SIMPLE(x, a, e); |
59 | else |
60 | EXP_WINDOW(x, a, e); |
61 | mp_drop(d); |
62 | mp_drop(spare); |
63 | mp_drop(a); |
64 | return (x); |
65 | } |
66 | |
67 | /*----- That's all, folks -------------------------------------------------*/ |