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