Pollard's rho algorithm for computing discrete logs.

[u/mdw/catacomb] / primorial.c

/* -*-c-*-
 *
 * $Id: primorial.c,v 1.2 2000/07/09 21:31:43 mdw Exp $
 *
 * Computes the product of the small primes
 *
 * (c) 1999 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of Catacomb.
 *
 * Catacomb is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * Catacomb is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with Catacomb; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: primorial.c,v $
 * Revision 1.2  2000/07/09 21:31:43  mdw
 * Use `mpmul'.
 *
 * Revision 1.1  1999/12/22 15:51:02  mdw
 * Calculate product of small primes for DSA prime search.
 *
 */

/*----- Header files ------------------------------------------------------*/

#include "mp.h"
#include "mpmul.h"
#include "primetab.h"

/*----- Global variables --------------------------------------------------*/

mp *primorial = 0;

/*----- Main code ---------------------------------------------------------*/

/* --- @primorial_setup@ --- *
 *
 * Arguments:	---
 *
 * Returns:	---
 *
 * Use:		Computes the product of the small primes in the table
 *		@primetab@.
 */

void primorial_setup(void)
{
  mp *p = MP_NEW;
  mpmul mm = MPMUL_INIT;
  int i;

  if (primorial)
    return;

  for (i = 0; i < NPRIME; i++) {
    p = mp_fromuint(p, primetab[i]);
    mpmul_add(&mm, p);
  }
  mp_drop(p);
  primorial = mpmul_done(&mm);
  mp_minimize(p);
}

/*----- That's all, folks -------------------------------------------------*/