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