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1 | /* -*-c-*- |
2 | * |
22bab86c |
3 | * $Id: prim.c,v 1.3 2000/10/08 12:11:22 mdw Exp $ |
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4 | * |
5 | * Finding primitive elements |
6 | * |
7 | * (c) 1999 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 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: prim.c,v $ |
22bab86c |
33 | * Revision 1.3 2000/10/08 12:11:22 mdw |
34 | * Use @MP_EQ@ instead of @MP_CMP@. |
35 | * |
6f80d39f |
36 | * Revision 1.2 2000/07/29 09:57:42 mdw |
37 | * Improve primitive-element testing a lot. Now much more sensible and |
38 | * orthogonal: you can find a generator for any given subgroup order by |
39 | * putting in the appropriate parameters. |
40 | * |
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41 | * Revision 1.1 1999/12/22 15:58:59 mdw |
42 | * Search for primitive elements using prime-search equipment. |
43 | * |
44 | */ |
45 | |
46 | /*----- Header files ------------------------------------------------------*/ |
47 | |
48 | #include "mp.h" |
49 | #include "mpint.h" |
50 | #include "mpmont.h" |
51 | #include "mprand.h" |
52 | #include "pgen.h" |
53 | #include "prim.h" |
54 | |
55 | /*----- Main code ---------------------------------------------------------*/ |
56 | |
57 | /* --- @prim_test@ --- */ |
58 | |
59 | int prim_test(int rq, pgen_event *ev, void *p) |
60 | { |
61 | prim_ctx *c = p; |
62 | int rc = rq; |
63 | |
64 | switch (rq) { |
65 | case PGEN_BEGIN: |
66 | return (PGEN_TRY); |
67 | case PGEN_TRY: { |
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68 | mp *x; |
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69 | rc = PGEN_FAIL; |
70 | |
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71 | if (!c->exp) |
72 | x = mp_copy(ev->m); |
73 | else { |
74 | x = mpmont_exp(&c->mm, MP_NEW, ev->m, c->exp); |
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75 | if (MP_EQ(x, MP_ONE)) |
6f80d39f |
76 | goto done; |
77 | } |
78 | if (c->n == 0) |
79 | goto ok; |
80 | else { |
81 | size_t n = c->n; |
82 | mp **f = c->f; |
83 | mp *y = MP_NEW; |
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84 | while (n) { |
6f80d39f |
85 | y = mpmont_exp(&c->mm, y, x, *f); |
22bab86c |
86 | if (MP_EQ(y, MP_ONE)) { |
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87 | mp_drop(y); |
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88 | goto done; |
6f80d39f |
89 | } |
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90 | n--; f++; |
91 | } |
6f80d39f |
92 | mp_drop(y); |
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93 | } |
6f80d39f |
94 | ok: |
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95 | rc = PGEN_DONE; |
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96 | mp_drop(ev->m); |
97 | ev->m = x; |
98 | break; |
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99 | done: |
100 | mp_drop(x); |
101 | } break; |
102 | } |
103 | |
104 | return (rc); |
105 | } |
106 | |
107 | /* --- Trivial stepping functions -----------------------------------------*/ |
108 | |
109 | /* --- @prim_step@ --- */ |
110 | |
111 | int prim_step(int rq, pgen_event *ev, void *p) |
112 | { |
113 | unsigned *i = p; |
114 | switch (rq) { |
115 | case PGEN_BEGIN: |
116 | case PGEN_TRY: |
117 | if (*i >= NPRIME) |
118 | return PGEN_FAIL; |
119 | ev->m = mp_fromint(ev->m, primetab[(*i)++]); |
120 | return (PGEN_TRY); |
121 | } |
122 | return (0); |
123 | } |
124 | |
125 | /*----- That's all, folks -------------------------------------------------*/ |