ae747c9b |
1 | /* -*-c-*- |
2 | * |
4e66da02 |
3 | * $Id: gfx-sqr.c,v 1.3 2004/04/02 01:03:49 mdw Exp $ |
ae747c9b |
4 | * |
5 | * Sqaring binary polynomials |
6 | * |
7 | * (c) 2000 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: gfx-sqr.c,v $ |
4e66da02 |
33 | * Revision 1.3 2004/04/02 01:03:49 mdw |
34 | * Miscellaneous constification. |
35 | * |
c3caa2fa |
36 | * Revision 1.2 2004/03/21 22:52:06 mdw |
37 | * Merge and close elliptic curve branch. |
38 | * |
ceb3f0c0 |
39 | * Revision 1.1.4.1 2004/03/21 22:39:46 mdw |
40 | * Elliptic curves on binary fields work. |
41 | * |
ae747c9b |
42 | * Revision 1.1 2000/10/08 15:49:37 mdw |
43 | * First glimmerings of binary polynomial arithmetic. |
44 | * |
45 | */ |
46 | |
47 | /*----- Header files ------------------------------------------------------*/ |
48 | |
49 | #include "mpx.h" |
ceb3f0c0 |
50 | #include "gfx.h" |
ae747c9b |
51 | #include "gfx-sqr-tab.h" |
52 | |
53 | /*----- Static variables --------------------------------------------------*/ |
54 | |
4e66da02 |
55 | static const uint16 tab[256] = GFX_SQRTAB; |
ae747c9b |
56 | |
57 | /*----- Main code ---------------------------------------------------------*/ |
58 | |
59 | /* --- @gfx_sqr@ --- * |
60 | * |
61 | * Arguments: @mpw *dv, *dvl@ = destination vector base and limit |
62 | * @const mpw *av, *avl@ = argument vector base and limit |
63 | * |
64 | * Returns: --- |
65 | * |
66 | * Use: Performs squaring of binary polynomials. |
67 | */ |
68 | |
69 | void gfx_sqr(mpw *dv, mpw *dvl, const mpw *av, const mpw *avl) |
70 | { |
71 | mpd a = 0, aa = 0; |
72 | unsigned b = 0, bb = 0; |
73 | |
74 | /* --- Simple stuff --- */ |
75 | |
76 | if (dv >= dvl) |
77 | return; |
78 | MPX_SHRINK(av, avl); |
79 | |
80 | /* --- The main algorithm --- * |
81 | * |
82 | * Our method depends on the fact that, in a field of characteristic 2, we |
83 | * have that %$(a + b)^2 = a^2 + b^2$%. Thus, to square a polynomial, it's |
84 | * sufficient just to put a zero bit between each of the bits of the |
85 | * original argument. We use a precomputed table for this, and work on |
86 | * entire octets at a time. Life is more complicated because we've got to |
87 | * be careful of bizarre architectures which don't have words with a |
88 | * multiple of 8 bits in them. |
89 | */ |
90 | |
91 | for (;;) { |
92 | |
93 | /* --- Input buffering --- */ |
94 | |
95 | if (b < 8) { |
96 | if (av >= avl) |
97 | break; |
98 | a |= *av++ << b; |
99 | b += MPW_BITS; |
100 | } |
101 | |
102 | /* --- Do the work in the middle --- */ |
103 | |
104 | aa |= (mpd)(tab[U8(a)]) << bb; |
105 | bb += 16; |
106 | a >>= 8; |
107 | b -= 8; |
108 | |
109 | /* --- Output buffering --- */ |
110 | |
ceb3f0c0 |
111 | if (bb >= MPW_BITS) { |
ae747c9b |
112 | *dv++ = MPW(aa); |
113 | if (dv >= dvl) |
114 | return; |
115 | aa >>= MPW_BITS; |
116 | bb -= MPW_BITS; |
117 | } |
118 | } |
119 | |
120 | /* --- Flush the input buffer --- */ |
121 | |
122 | if (b) for (;;) { |
123 | aa |= (mpd)(tab[U8(a)]) << bb; |
124 | bb += 16; |
125 | if (bb > MPW_BITS) { |
126 | *dv++ = MPW(aa); |
127 | if (dv >= dvl) |
128 | return; |
129 | aa >>= MPW_BITS; |
130 | bb -= MPW_BITS; |
131 | } |
132 | a >>= 8; |
133 | if (b <= 8) |
134 | break; |
135 | else |
136 | b -= 8; |
137 | } |
138 | |
139 | /* --- Flush the output buffer --- */ |
140 | |
141 | if (bb) for (;;) { |
142 | *dv++ = MPW(aa); |
143 | if (dv >= dvl) |
144 | return; |
145 | aa >>= MPW_BITS; |
146 | if (bb <= MPW_BITS) |
147 | break; |
148 | else |
149 | bb -= MPW_BITS; |
150 | } |
151 | |
152 | /* --- Zero the rest of everything --- */ |
153 | |
154 | MPX_ZERO(dv, dvl); |
155 | } |
156 | |
157 | /*----- Test rig ----------------------------------------------------------*/ |
158 | |
159 | #ifdef TEST_RIG |
160 | |
161 | #include <mLib/alloc.h> |
162 | #include <mLib/dstr.h> |
163 | #include <mLib/quis.h> |
164 | #include <mLib/testrig.h> |
165 | |
166 | #define ALLOC(v, vl, sz) do { \ |
167 | size_t _sz = (sz); \ |
168 | mpw *_vv = xmalloc(MPWS(_sz)); \ |
169 | mpw *_vvl = _vv + _sz; \ |
170 | (v) = _vv; \ |
171 | (vl) = _vvl; \ |
172 | } while (0) |
173 | |
174 | #define LOAD(v, vl, d) do { \ |
175 | const dstr *_d = (d); \ |
176 | mpw *_v, *_vl; \ |
177 | ALLOC(_v, _vl, MPW_RQ(_d->len)); \ |
178 | mpx_loadb(_v, _vl, _d->buf, _d->len); \ |
179 | (v) = _v; \ |
180 | (vl) = _vl; \ |
181 | } while (0) |
182 | |
183 | #define MAX(x, y) ((x) > (y) ? (x) : (y)) |
184 | |
185 | static void dumpmp(const char *msg, const mpw *v, const mpw *vl) |
186 | { |
187 | fputs(msg, stderr); |
188 | MPX_SHRINK(v, vl); |
189 | while (v < vl) |
190 | fprintf(stderr, " %08lx", (unsigned long)*--vl); |
191 | fputc('\n', stderr); |
192 | } |
193 | |
194 | static int vsqr(dstr *v) |
195 | { |
196 | mpw *a, *al; |
197 | mpw *b, *bl; |
198 | mpw *d, *dl; |
199 | int ok = 1; |
200 | |
201 | LOAD(a, al, &v[0]); |
202 | LOAD(b, bl, &v[1]); |
203 | ALLOC(d, dl, 2 * (al - a)); |
204 | |
205 | gfx_sqr(d, dl, a, al); |
206 | if (!mpx_ueq(d, dl, b, bl)) { |
207 | fprintf(stderr, "\n*** vsqr failed\n"); |
208 | dumpmp(" a", a, al); |
209 | dumpmp("expected", b, bl); |
210 | dumpmp(" result", d, dl); |
211 | ok = 0; |
212 | } |
213 | |
214 | free(a); free(b); free(d); |
215 | return (ok); |
216 | } |
217 | |
218 | static test_chunk defs[] = { |
219 | { "sqr", vsqr, { &type_hex, &type_hex, 0 } }, |
220 | { 0, 0, { 0 } } |
221 | }; |
222 | |
223 | int main(int argc, char *argv[]) |
224 | { |
225 | test_run(argc, argv, defs, SRCDIR"/tests/gfx"); |
226 | return (0); |
227 | } |
228 | |
229 | #endif |
230 | |
231 | /*----- That's all, folks -------------------------------------------------*/ |