First glimmerings of binary polynomial arithmetic.

[u/mdw/catacomb] / gfx.h

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+/* -*-c-*-
+ *
+ * $Id: gfx.h,v 1.1 2000/10/08 15:49:37 mdw Exp $
+ *
+ * Low-level arithmetic on binary polynomials
+ *
+ * (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.h,v $
+ * Revision 1.1  2000/10/08 15:49:37  mdw
+ * First glimmerings of binary polynomial arithmetic.
+ *
+ */
+
+#ifndef CATACOMB_GFX_H
+#define CATACOMB_GFX_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#ifndef CATACOMB_MPX_H
+#  include "mpx.h"
+#endif
+
+/*----- Functions provided ------------------------------------------------*/
+
+/* --- @gfx_add@ --- *
+ *
+ * Arguments:  @mpw *dv, *dvl@ = destination vector base and limit
+ *             @const mpw *av, *avl@ = first addend vector base and limit
+ *             @const mpw *bv, *bvl@ = second addend vector base and limit
+ *
+ * Returns:    ---
+ *
+ * Use:                Adds two %$\gf{2}$% polynomials.  This is the same as
+ *             subtraction.
+ */
+
+extern void gfx_add(mpw */*dv*/, mpw */*dvl*/,
+                   const mpw */*av*/, const mpw */*avl*/,
+                   const mpw */*bv*/, const mpw */*bvl*/);
+
+/* --- @gfx_acc@ --- *
+ *
+ * Arguments:  @mpw *dv, *dvl@ = destination vector base and limit
+ *             @const mpw *av, *avl@ = addend vector base and limit
+ *
+ * Returns:    ---
+ *
+ * Use:                Adds the addend into the destination.  This is considerably
+ *             faster than the three-address add call.
+ */
+
+extern void gfx_acc(mpw */*dv*/, mpw */*dvl*/,
+                   const mpw */*av*/, const mpw */*avl*/);
+
+/* --- @gfx_accshift@ --- *
+ *
+ * Arguments:  @mpw *dv, *dvl@ = destination vector base and limit
+ *             @const mpw *av, *avl@ = addend vector base and limit
+ *             @size_t n@ = number of bits to shift
+ *
+ * Returns:    ---
+ *
+ * Use:                Shifts the argument left by %$n$% places and adds it to the
+ *             destination.  This is a primitive used by multiplication and
+ *             division.
+ */
+
+extern void gfx_accshift(mpw */*dv*/, mpw */*dvl*/,
+                        const mpw */*av*/, const mpw */*avl*/,
+                        size_t /*n*/);
+
+/* --- @gfx_mul@ --- *
+ *
+ * Arguments:  @mpw *dv, *dvl@ = destination vector base and limit
+ *             @const mpw *av, *avl@ = first argument vector base and limit
+ *             @const mpw *bv, *bvl@ = second argument vector base and limit
+ *
+ * Returns:    ---
+ *
+ * Use:                Does multiplication of polynomials over %$\gf{2}$%.
+ */
+
+extern void gfx_mul(mpw */*dv*/, mpw */*dvl*/,
+                   const mpw */*av*/, const mpw */*avl*/,
+                   const mpw */*bv*/, const mpw */*bvl*/);
+
+/* --- @gfx_div@ --- *
+ *
+ * Arguments:  @mpw *qv, *qvl@ = quotient vector base and limit
+ *              @mpw *rv, *rvl@ = dividend/remainder vector base and limit
+ *              @const mpw *dv, *dvl@ = divisor vector base and limit
+ *
+ * Returns:     ---
+ *
+ * Use:         Performs division on polynomials over %$\gf{2}$%.
+ */
+
+extern void gfx_div(mpw */*qv*/, mpw */*qvl*/, mpw */*rv*/, mpw */*rvl*/,
+                   const mpw */*dv*/, const mpw */*dvl*/);
+
+/*----- Karatsuba multiplication algorithms -------------------------------*/
+
+/* --- @GFK_THRESH@ --- *
+ *
+ * This is the limiting length for using Karatsuba algorithms.  It's best to
+ * use the simpler classical multiplication method on numbers smaller than
+ * this.
+ */
+
+#define GFK_THRESH 2
+
+/* --- @gfx_kmul@ --- *
+ *
+ * Arguments:  @mpw *dv, *dvl@ = pointer to destination buffer
+ *             @const mpw *av, *avl@ = pointer to first argument
+ *             @const mpw *bv, *bvl@ = pointer to second argument
+ *             @mpw *sv, *svl@ = pointer to scratch workspace
+ *
+ * Returns:    ---
+ *
+ * Use:                Multiplies two binary polynomials using Karatsuba's
+ *             algorithm.  This is rather faster than traditional long
+ *             multiplication (e.g., @gfx_umul@) on polynomials with large
+ *             degree, although more expensive on small ones.
+ *
+ *             The destination must be twice as large as the larger
+ *             argument.  The scratch space must be twice as large as the
+ *             larger argument.
+ */
+
+extern void gfx_kmul(mpw */*dv*/, mpw */*dvl*/,
+                    const mpw */*av*/, const mpw */*avl*/,
+                    const mpw */*bv*/, const mpw */*bvl*/,
+                    mpw */*sv*/, mpw */*svl*/);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif