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

   1 /* -*-c-*-
   2  *
   3  * $Id: primorial.c,v 1.2 2000/07/09 21:31:43 mdw Exp $
   4  *
   5  * Computes the product of the small primes
   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: primorial.c,v $
  33  * Revision 1.2  2000/07/09 21:31:43  mdw
  34  * Use `mpmul'.
  35  *
  36  * Revision 1.1  1999/12/22 15:51:02  mdw
  37  * Calculate product of small primes for DSA prime search.
  38  *
  39  */
  40
  41 /*----- Header files ------------------------------------------------------*/
  42
  43 #include "mp.h"
  44 #include "mpmul.h"
  45 #include "primetab.h"
  46
  47 /*----- Global variables --------------------------------------------------*/
  48
  49 mp *primorial = 0;
  50
  51 /*----- Main code ---------------------------------------------------------*/
  52
  53 /* --- @primorial_setup@ --- *
  54  *
  55  * Arguments:   ---
  56  *
  57  * Returns:     ---
  58  *
  59  * Use:         Computes the product of the small primes in the table
  60  *              @primetab@.
  61  */
  62
  63 void primorial_setup(void)
  64 {
  65   mp *p = MP_NEW;
  66   mpmul mm = MPMUL_INIT;
  67   int i;
  68
  69   if (primorial)
  70     return;
  71
  72   for (i = 0; i < NPRIME; i++) {
  73     p = mp_fromuint(p, primetab[i]);
  74     mpmul_add(&mm, p);
  75   }
  76   mp_drop(p);
  77   primorial = mpmul_done(&mm);
  78   mp_minimize(p);
  79 }
  80
  81 /*----- That's all, folks -------------------------------------------------*/