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   1 /* -*-c-*-
   2  *
   3  * $Id: gfreduce.h,v 1.3 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * Reduction modulo sparse binary polynomials
   6  *
   7  * (c) 2004 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 #ifndef CATACOMB_GFREDUCE_H
  31 #define CATACOMB_GFREDUCE_H
  32
  33 #ifdef __cplusplus
  34   extern "C" {
  35 #endif
  36
  37 /*----- Header files ------------------------------------------------------*/
  38
  39 #ifndef CATACOMB_GF_H
  40 #  include "gf.h"
  41 #endif
  42
  43 /*----- Data structures ---------------------------------------------------*/
  44
  45 typedef struct gfreduce_instr {
  46   unsigned op;                          /* Instruction opcode */
  47   size_t arg;                           /* Immediate argument */
  48 } gfreduce_instr;
  49
  50 enum {
  51   GFRI_LOAD,                            /* Load @p[arg]@ */
  52   GFRI_LSL,                             /* XOR with @w << arg@ */
  53   GFRI_LSR,                             /* XOR with @w >> arg@ */
  54   GFRI_STORE,                           /* Store @p[arg]@ */
  55   GFRI_MAX
  56 };
  57
  58 typedef struct gfreduce {
  59   size_t lim;                           /* Word of degree bit */
  60   mpw mask;                             /* Mask for degree word */
  61   mp *p;                                /* Copy of the polynomial */
  62   size_t in;                            /* Number of instruction words */
  63   gfreduce_instr *iv, *liv;             /* Vector of instructions */
  64 } gfreduce;
  65
  66 /*----- Functions provided ------------------------------------------------*/
  67
  68 /* --- @gfreduce_create@ --- *
  69  *
  70  * Arguments:   @gfreduce *r@ = structure to fill in
  71  *              @mp *x@ = a (hopefully sparse) polynomial
  72  *
  73  * Returns:     ---
  74  *
  75  * Use:         Initializes a context structure for reduction.
  76  */
  77
  78 extern void gfreduce_create(gfreduce */*r*/, mp */*p*/);
  79
  80 /* --- @gfreduce_destroy@ --- *
  81  *
  82  * Arguments:   @gfreduce *r@ = structure to free
  83  *
  84  * Returns:     ---
  85  *
  86  * Use:         Reclaims the resources from a reduction context.
  87  */
  88
  89 extern void gfreduce_destroy(gfreduce */*r*/);
  90
  91 /* --- @gfreduce_dump@ --- *
  92  *
  93  * Arguments:   @gfreduce *r@ = structure to dump
  94  *              @FILE *fp@ = file to dump on
  95  *
  96  * Returns:     ---
  97  *
  98  * Use:         Dumps a reduction context.
  99  */
 100
 101 extern void gfreduce_dump(gfreduce */*r*/, FILE */*fp*/);
 102
 103 /* --- @gfreduce_do@ --- *
 104  *
 105  * Arguments:   @gfreduce *r@ = reduction context
 106  *              @mp *d@ = destination
 107  *              @mp *x@ = source
 108  *
 109  * Returns:     Destination, @x@ reduced modulo the reduction poly.
 110  */
 111
 112 extern mp *gfreduce_do(gfreduce */*r*/, mp */*d*/, mp */*x*/);
 113
 114 /* --- @gfreduce_sqrt@ --- *
 115  *
 116  * Arguments:   @gfreduce *r@ = pointer to reduction context
 117  *              @mp *d@ = destination
 118  *              @mp *x@ = some polynomial
 119  *
 120  * Returns:     The square root of @x@ modulo @r->p@, or null.
 121  */
 122
 123 extern mp *gfreduce_sqrt(gfreduce */*r*/, mp */*d*/, mp */*x*/);
 124
 125 /* --- @gfreduce_trace@ --- *
 126  *
 127  * Arguments:   @gfreduce *r@ = pointer to reduction context
 128  *              @mp *x@ = some polynomial
 129  *
 130  * Returns:     The trace of @x@. (%$\Tr(x)=x + x^2 + \cdots + x^{2^{m-1}}$%
 131  *              if %$x \in \gf{2^m}$%).
 132  */
 133
 134 extern int gfreduce_trace(gfreduce */*r*/, mp */*x*/);
 135
 136 /* --- @gfreduce_halftrace@ --- *
 137  *
 138  * Arguments:   @gfreduce *r@ = pointer to reduction context
 139  *              @mp *d@ = destination
 140  *              @mp *x@ = some polynomial
 141  *
 142  * Returns:     The half-trace of @x@.
 143  *              (%$\HfTr(x)= x + x^{2^2} + \cdots + x^{2^{m-1}}$%
 144  *              if %$x \in \gf{2^m}$% with %$m$% odd).
 145  */
 146
 147 extern mp *gfreduce_halftrace(gfreduce */*r*/, mp */*d*/, mp */*x*/);
 148
 149 /* --- @gfreduce_quadsolve@ --- *
 150  *
 151  * Arguments:   @gfreduce *r@ = pointer to reduction context
 152  *              @mp *d@ = destination
 153  *              @mp *x@ = some polynomial
 154  *
 155  * Returns:     A polynomial @y@ such that %$y^2 + y = x$%, or null.
 156  */
 157
 158 extern mp *gfreduce_quadsolve(gfreduce */*r*/, mp */*d*/, mp */*x*/);
 159
 160 /* --- @gfreduce_exp@ --- *
 161  *
 162  * Arguments:   @gfreduce *gr@ = pointer to reduction context
 163  *              @mp *d@ = fake destination
 164  *              @mp *a@ = base
 165  *              @mp *e@ = exponent
 166  *
 167  * Returns:     Result, %$a^e \bmod m$%.
 168  */
 169
 170 extern mp *gfreduce_exp(gfreduce */*gr*/, mp */*d*/, mp */*a*/, mp */*e*/);
 171
 172 /*----- That's all, folks -------------------------------------------------*/
 173
 174 #ifdef __cplusplus
 175   }
 176 #endif
 177
 178 #endif