git.distorted.org.uk Git - u/mdw/catacomb/blob - mptext-string.c

   1 /* -*-c-*-
   2  *
   3  * $Id: mptext-string.c,v 1.4 2004/04/01 12:50:09 mdw Exp $
   4  *
   5  * Reading and writing large integers on strings
   6  *
   7  * (c) 1999 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: mptext-string.c,v $
  33  * Revision 1.4  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  * Revision 1.3  2000/08/04 23:23:44  mdw
  41  * Various <ctype.h> fixes.
  42  *
  43  * Revision 1.2  1999/12/22 15:56:21  mdw
  44  * Make the buffer passed to `put' op constant.
  45  *
  46  * Revision 1.1  1999/11/17 18:02:16  mdw
  47  * New multiprecision integer arithmetic suite.
  48  *
  49  */
  50
  51 /*----- Header files ------------------------------------------------------*/
  52
  53 #include <string.h>
  54
  55 #include "mptext.h"
  56
  57 /*----- Main code ---------------------------------------------------------*/
  58
  59 /* --- Operations table --- */
  60
  61 static int get(void *p)
  62 {
  63   mptext_stringctx *c = p;
  64   if (c->buf >= c->lim)
  65     return (EOF);
  66   return ((unsigned char)*c->buf++);
  67 }
  68
  69 static void unget(int ch, void *p)
  70 {
  71   mptext_stringctx *c = p;
  72   if (ch != EOF)
  73     c->buf--;
  74 }
  75
  76 static int put(const char *s, size_t sz, void *p)
  77 {
  78   mptext_stringctx *c = p;
  79   int rc = 0;
  80   if (sz > c->lim - c->buf) {
  81     sz = c->lim - c->buf;
  82     rc = EOF;
  83   }
  84   if (sz) {
  85     memcpy(c->buf, s, sz);
  86     c->buf += sz;
  87   }
  88   return (rc);
  89 }
  90
  91 const mptext_ops mptext_stringops = { get, unget, put };
  92
  93 /* --- Convenience functions --- */
  94
  95 mp *mp_readstring(mp *m, const char *p, char **end, int radix)
  96 {
  97   mptext_stringctx c;
  98   c.buf = (/*unconst */ char *)p;
  99   c.lim = c.buf + strlen(p);
 100   m = mp_read(m, radix, &mptext_stringops, &c);
 101   if (end)
 102     *end = c.buf;
 103   return (m);
 104 }
 105
 106 int mp_writestring(mp *m, char *p, size_t sz, int radix)
 107 {
 108   mptext_stringctx c;
 109   int rc;
 110   if (!sz)
 111     return (0);
 112   c.buf = p;
 113   c.lim = p + sz - 1;
 114   rc = mp_write(m, radix, &mptext_stringops, &c);
 115   *c.buf = 0;
 116   return (rc);
 117 }
 118
 119 /*----- That's all, folks -------------------------------------------------*/