X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/7c0acba656af3823577d1341f39c0bbe86632681..a2a74efe4b1276b1efec12f25fd65f0df060f38a:/calc/gfx.cal

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+/* -*-apcalc-*-
+ *
+ * $Id: gfx.cal,v 1.1 2000/10/08 16:01:37 mdw Exp $
+ *
+ * Testbed for %$\gf{2}$% poltnomial arithmetic
+ *
+ * (c) 2000 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------* 
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ * 
+ * Catacomb is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Library General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Library General Public
+ * License along with Catacomb; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------* 
+ *
+ * $Log: gfx.cal,v $
+ * Revision 1.1  2000/10/08 16:01:37  mdw
+ * Prototypes of various bits of code.
+ *
+ */
+
+/*----- Object types ------------------------------------------------------*/
+
+obj gf { x };
+
+/*----- Static variables --------------------------------------------------*/
+
+static obj gf example_gf_object;
+
+/*----- Main code ---------------------------------------------------------*/
+
+dummy = config("lib_debug", -1);
+
+define gf(x)
+{
+  local obj gf g;
+  g.x = x;
+  return (g);
+}
+
+define gfint(x)
+{
+  if (istype(x, example_gf_object))
+    return (x.x);
+  else
+    return (x);
+}
+
+define gf_add(x, y) = gf(xor(gfint(x), gfint(y)));
+define gf_sub(x, y) = gf(xor(gfint(x), gfint(y)));
+define gf_neg(x) = x;
+
+define gf_mul(x, y)
+{
+  local a = gfint(x), b = gfint(y), z = 0, i, bits = highbit(a);
+  for (i = 0; i <= bits; i++) {
+    if (bit(a, i))
+      z = xor(z, b << i);
+  }
+  return gf(z);
+}
+
+define gfx_div(rx, dx)
+{
+  local r = gfint(rx), d = gfint(dx), i;
+  local q = 0, dbits = highbit(d), rbits = highbit(r);
+  for (i = rbits - dbits; i >= 0; i--) {
+    if (bit(r, i + dbits)) {
+      r = xor(r, d << i);
+      q |= (1 << i);
+    }
+  }
+  return list(q, r);
+}
+
+define gf_div(x, y)
+{
+  local l = gfx_div(x, y);
+  return gf(l[[0]]);
+}
+
+define gf_mod(x, y)
+{
+  local l = gfx_div(x, y);
+  return gf(l[[1]]);
+}
+
+/*----- That's all, folks -------------------------------------------------*/