3 * $Id: gfx.cal,v 1.3 2004/04/08 01:36:15 mdw Exp $
5 * Testbed for %$\gf{2}$% poltnomial arithmetic
7 * (c) 2000 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Object types ------------------------------------------------------*/
34 /*----- Static variables --------------------------------------------------*/
36 static obj gf example_gf_object;
38 /*----- Main code ---------------------------------------------------------*/
40 dummy = config("lib_debug", -1);
51 if (istype(x, example_gf_object))
57 define gf_add(x, y) = gf(xor(gfint(x), gfint(y)));
58 define gf_sub(x, y) = gf(xor(gfint(x), gfint(y)));
63 local a = gfint(x), b = gfint(y), z = 0, i, bits = highbit(a);
64 for (i = 0; i <= bits; i++) {
71 define gfx_div(rx, dx)
73 local r = gfint(rx), d = gfint(dx), i;
74 local q = 0, dbits, rbits;
77 for (i = rbits - dbits; i >= 0; i--) {
78 if (bit(r, i + dbits)) {
103 local g, x = 1, X = 0, y = 0, Y = 1, q, r, t;
112 q = gf_div(a, b); r = gf_mod(a, b);
113 t = X * q + x; x = X; X = t;
114 t = Y * q + y; y = Y; Y = t;
122 return list(g, x, y);
127 local l = gf_gcd(b, a);
128 if (l[[0]] != gf(1)) quit "not coprime in gf_inv";
132 /*----- That's all, folks -------------------------------------------------*/