3 * Testbed for %$\gf{2}$% poltnomial arithmetic
5 * (c) 2000 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Catacomb.
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.
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.
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,
28 /*----- Object types ------------------------------------------------------*/
32 /*----- Static variables --------------------------------------------------*/
34 static obj gf example_gf_object;
36 /*----- Main code ---------------------------------------------------------*/
38 dummy = config("lib_debug", -1);
49 if (istype(x, example_gf_object))
55 define gf_add(x, y) = gf(xor(gfint(x), gfint(y)));
56 define gf_sub(x, y) = gf(xor(gfint(x), gfint(y)));
61 local a = gfint(x), b = gfint(y), z = 0, i, bits = highbit(a);
62 for (i = 0; i <= bits; i++) {
69 define gfx_div(rx, dx)
71 local r = gfint(rx), d = gfint(dx), i;
72 local q = 0, dbits, rbits;
75 for (i = rbits - dbits; i >= 0; i--) {
76 if (bit(r, i + dbits)) {
101 local g, x = 1, X = 0, y = 0, Y = 1, q, r, t;
110 q = gf_div(a, b); r = gf_mod(a, b);
111 t = X * q + x; x = X; X = t;
112 t = Y * q + y; y = Y; Y = t;
120 return list(g, x, y);
125 local l = gf_gcd(b, a);
126 if (l[[0]] != gf(1)) quit "not coprime in gf_inv";
130 /*----- That's all, folks -------------------------------------------------*/