| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: gfx-sqr.c,v 1.3 2004/04/02 01:03:49 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 1.3 2004/04/02 01:03:49 mdw |
| 34 | * Miscellaneous constification. |
| 35 | * |
| 36 | * Revision 1.2 2004/03/21 22:52:06 mdw |
| 37 | * Merge and close elliptic curve branch. |
| 38 | * |
| 39 | * Revision 1.1.4.1 2004/03/21 22:39:46 mdw |
| 40 | * Elliptic curves on binary fields work. |
| 41 | * |
| 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" |
| 50 | #include "gfx.h" |
| 51 | #include "gfx-sqr-tab.h" |
| 52 | |
| 53 | /*----- Static variables --------------------------------------------------*/ |
| 54 | |
| 55 | static const uint16 tab[256] = GFX_SQRTAB; |
| 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 | |
| 111 | if (bb >= MPW_BITS) { |
| 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 -------------------------------------------------*/ |