git.distorted.org.uk Git - u/mdw/catacomb/blob - calc/gfx.cal

   1 /* -*-apcalc-*-
   2  *
   3  * $Id: gfx.cal,v 1.1 2000/10/08 16:01:37 mdw Exp $
   4  *
   5  * Testbed for %$\gf{2}$% poltnomial arithmetic
   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.cal,v $
  33  * Revision 1.1  2000/10/08 16:01:37  mdw
  34  * Prototypes of various bits of code.
  35  *
  36  */
  37
  38 /*----- Object types ------------------------------------------------------*/
  39
  40 obj gf { x };
  41
  42 /*----- Static variables --------------------------------------------------*/
  43
  44 static obj gf example_gf_object;
  45
  46 /*----- Main code ---------------------------------------------------------*/
  47
  48 dummy = config("lib_debug", -1);
  49
  50 define gf(x)
  51 {
  52   local obj gf g;
  53   g.x = x;
  54   return (g);
  55 }
  56
  57 define gfint(x)
  58 {
  59   if (istype(x, example_gf_object))
  60     return (x.x);
  61   else
  62     return (x);
  63 }
  64
  65 define gf_add(x, y) = gf(xor(gfint(x), gfint(y)));
  66 define gf_sub(x, y) = gf(xor(gfint(x), gfint(y)));
  67 define gf_neg(x) = x;
  68
  69 define gf_mul(x, y)
  70 {
  71   local a = gfint(x), b = gfint(y), z = 0, i, bits = highbit(a);
  72   for (i = 0; i <= bits; i++) {
  73     if (bit(a, i))
  74       z = xor(z, b << i);
  75   }
  76   return gf(z);
  77 }
  78
  79 define gfx_div(rx, dx)
  80 {
  81   local r = gfint(rx), d = gfint(dx), i;
  82   local q = 0, dbits = highbit(d), rbits = highbit(r);
  83   for (i = rbits - dbits; i >= 0; i--) {
  84     if (bit(r, i + dbits)) {
  85       r = xor(r, d << i);
  86       q |= (1 << i);
  87     }
  88   }
  89   return list(q, r);
  90 }
  91
  92 define gf_div(x, y)
  93 {
  94   local l = gfx_div(x, y);
  95   return gf(l[[0]]);
  96 }
  97
  98 define gf_mod(x, y)
  99 {
 100   local l = gfx_div(x, y);
 101   return gf(l[[1]]);
 102 }
 103
 104 /*----- That's all, folks -------------------------------------------------*/