git.distorted.org.uk Git - u/mdw/catacomb/blob - group-dstr.c

   1 /* -*-c-*-
   2  *
   3  * $Id: group-dstr.c,v 1.1 2004/04/01 12:50:09 mdw Exp $
   4  *
   5  * Dynamic string I/O for group elements
   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 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: group-dstr.c,v $
  33  * Revision 1.1  2004/04/01 12:50:09  mdw
  34  * Add cyclic group abstraction, with test code.  Separate off exponentation
  35  * functions for better static linking.  Fix a buttload of bugs on the way.
  36  * Generally ensure that negative exponents do inversion correctly.  Add
  37  * table of standard prime-field subgroups.  (Binary field subgroups are
  38  * currently unimplemented but easy to add if anyone ever finds a good one.)
  39  *
  40  */
  41
  42 /*----- Header files ------------------------------------------------------*/
  43
  44 #include "group.h"
  45
  46 /*----- Main code ---------------------------------------------------------*/
  47
  48 /* --- @group_readdstr@ --- *
  49  *
  50  * Arguments:   @group *g@ = an abstract group
  51  *              @ge *d@ = destination group element
  52  *              @dstr *dd@ = string to read from
  53  *              @size_t *off@ = offset to start at (updated)
  54  *
  55  * Returns:     Zero on success, nonzero on failure.
  56  *
  57  * Use:         Parses a group element from a dynamic string.
  58  */
  59
  60 int group_readdstr(group *g, ge *d, dstr *dd, size_t *off)
  61 {
  62   mptext_dstrctx md;
  63
  64   md.d = dd;
  65   md.i = off ? *off : 0;
  66   if (G_READ(g, d, &mptext_dstrops, &md))
  67     return (-1);
  68   if (off) *off = md.i;
  69   return (0);
  70 }
  71
  72 /* --- @group_writedstr@ --- *
  73  *
  74  * Arguments:   @group *g@ = an abstract group
  75  *              @ge *x@ = a group element
  76  *              @dstr *d@ = string to write to
  77  *              @size_t sz@ = how long the buffer is
  78  *
  79  * Returns:     Zero on success, nonzero on failure.
  80  *
  81  * Use:         Writes a group element to a dstr buffer.
  82  */
  83
  84 int group_writedstr(group *g, ge *x, dstr *d)
  85 {
  86   mptext_dstrctx md;
  87
  88   md.d = d;
  89   if (G_WRITE(g, x, &mptext_dstrops, &md))
  90     return (-1);
  91   DPUTZ(d);
  92   return (0);
  93 }
  94
  95
  96
  97 /*----- That's all, folks -------------------------------------------------*/