[u/mdw/catacomb] / mp-exp.c

/* -*-c-*-
 *
 * $Id$
 *
 * Exponentiation for large integers
 *
 * (c) 2004 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.
 */

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

#include <assert.h>

#include "mp.h"
#include "mp-exp.h"

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

/* --- @mp_exp@ --- *
 *
 * Arguments:	@mp *d@ = fake destination
 *		@mp *a@ = base
 *		@mp *e@ = exponent
 *
 * Returns:	Result, %$a^e$%.
 */

mp *mp_exp(mp *d, mp *a, mp *e)
{
  mp *x = MP_ONE;
  mp *spare = (e->f & MP_BURN) ? MP_NEWSEC : MP_NEW;
  assert(!MP_NEGP(e));

  MP_COPY(a);
  if (MP_ZEROP(e))
    ;
  else if (MP_LEN(e) < EXP_THRESH)
    EXP_SIMPLE(x, a, e);
  else
    EXP_WINDOW(x, a, e);
  mp_drop(d);
  mp_drop(spare);
  mp_drop(a);
  return (x);
}

/*----- That's all, folks -------------------------------------------------*/
Commit	Line	Data
f4535c64	1	/* --c--
	2	*
	3	* $Id$
	4	*
	5	* Exponentiation for large integers
	6	*
	7	* (c) 2004 Straylight/Edgeware
	8	*/
	9
45c0fd36	10	/----- Licensing notice --------------------------------------------------
f4535c64	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.
45c0fd36	18	*
f4535c64	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.
45c0fd36	23	*
f4535c64	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	/----- Header files ------------------------------------------------------/
	31
	32	#include <assert.h>
	33
	34	#include "mp.h"
	35	#include "mp-exp.h"
	36
	37	/----- Main code ---------------------------------------------------------/
	38
	39	/* --- @mp_exp@ --- *
	40	*
	41	* Arguments: @mp *d@ = fake destination
	42	* @mp *a@ = base
	43	* @mp *e@ = exponent
	44	*
	45	* Returns: Result, %$a^e$%.
	46	*/
	47
	48	mp mp_exp(mp d, mp a, mp e)
	49	{
	50	mp *x = MP_ONE;
	51	mp *spare = (e->f & MP_BURN) ? MP_NEWSEC : MP_NEW;
	52	assert(!MP_NEGP(e));
	53
	54	MP_COPY(a);
	55	if (MP_ZEROP(e))
	56	;
	57	else if (MP_LEN(e) < EXP_THRESH)
	58	EXP_SIMPLE(x, a, e);
	59	else
	60	EXP_WINDOW(x, a, e);
	61	mp_drop(d);
	62	mp_drop(spare);
	63	mp_drop(a);
	64	return (x);
	65	}
	66
	67	/----- That's all, folks -------------------------------------------------/