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

   1 /* -*-c-*-
   2  *
   3  * $Id: primorial.c,v 1.4 2000/08/15 21:41:09 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 1.4  2000/08/15 21:41:09  mdw
  34  * Bug fix: minimize the right thing.
  35  *
  36  * Revision 1.3  2000/07/15 10:02:07  mdw
  37  * Include missing header file.
  38  *
  39  * Revision 1.2  2000/07/09 21:31:43  mdw
  40  * Use `mpmul'.
  41  *
  42  * Revision 1.1  1999/12/22 15:51:02  mdw
  43  * Calculate product of small primes for DSA prime search.
  44  *
  45  */
  46
  47 /*----- Header files ------------------------------------------------------*/
  48
  49 #include "mp.h"
  50 #include "mpint.h"
  51 #include "mpmul.h"
  52 #include "primetab.h"
  53
  54 /*----- Global variables --------------------------------------------------*/
  55
  56 mp *primorial = 0;
  57
  58 /*----- Main code ---------------------------------------------------------*/
  59
  60 /* --- @primorial_setup@ --- *
  61  *
  62  * Arguments:   ---
  63  *
  64  * Returns:     ---
  65  *
  66  * Use:         Computes the product of the small primes in the table
  67  *              @primetab@.
  68  */
  69
  70 void primorial_setup(void)
  71 {
  72   mp *p = MP_NEW;
  73   mpmul mm = MPMUL_INIT;
  74   int i;
  75
  76   if (primorial)
  77     return;
  78
  79   for (i = 0; i < NPRIME; i++) {
  80     p = mp_fromuint(p, primetab[i]);
  81     mpmul_add(&mm, p);
  82   }
  83   mp_drop(p);
  84   primorial = mpmul_done(&mm);
  85   mp_minimize(primorial);
  86   primorial->a->n--; /* Permanent allocation */
  87 }
  88
  89 /*----- That's all, folks -------------------------------------------------*/