/*
 * zrandom - Blum-Blum-Shub pseudo-random generator
 *
 * Copyright (C) 1999-2007,2014  Landon Curt Noll
 *
 * Calc is open software; you can redistribute it and/or modify it under
 * the terms of the version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * Calc 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 Lesser General
 * Public License for more details.
 *
 * A copy of version 2.1 of the GNU Lesser General Public License is
 * distributed with calc under the filename COPYING-LGPL.  You should have
 * received a copy with calc; if not, write to Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Under source code control:	1997/02/15 04:01:56
 * File existed as early as:	1997
 *
 * chongo <was here> /\oo/\	http://www.isthe.com/chongo/
 * Share and enjoy!  :-)	http://www.isthe.com/chongo/tech/comp/calc/
 */


#if !defined(INCLUDE_ZRANDOM_H)
#define INCLUDE_ZRANDOM_H


#if defined(CALC_SRC)	/* if we are building from the calc source tree */
# include "calc/value.h"
# include "calc/have_const.h"
#else
# include <calc/value.h>
# include <calc/have_const.h>
#endif


/*
 * Blum generator state
 *
 * The size of the buffer implies that a turn of the quadratic residue crank
 * will never yield as many at the than the number of bits in a HALF.  At
 * most this implies that a turn can yield no more than 15 bits when BASEB==16
 * or 31 bits when BASEB==32.  Should we deal with a excessively large
 * Blum modulus (>=2^16 bits long for BASEB==16, >=2^32 bits for BASEB==32)
 * the higher order random bits will be tossed.	 This is not a loss as
 * regular sub-segments of the sequence are just as random.  It only means
 * that excessively large Blum modulus values waste CPU time.
 */
struct random {
	int seeded;	/* 1 => state has been seeded */
	int bits;	/* number of unused bits in buffer */
	int loglogn;	/* int(log2(log2(n))), bits produced per turn */
	HALF buffer;	/* unused random bits from previous call */
	HALF mask;	/* mask for the log2(log2(n)) lower bits of r */
	ZVALUE n;	/* Blum modulus */
	ZVALUE r;	/* Blum quadratic residue */
};


/*
 * Blum constants
 */
#define BLUM_PREGEN 20	/* number of non-default predefined Blum generators */


/*
 * Blum generator function declarations
 */
E_FUNC RANDOM *zsrandom1(CONST ZVALUE seed, bool need_ret);
E_FUNC RANDOM *zsrandom2(CONST ZVALUE seed, CONST ZVALUE newn);
E_FUNC RANDOM *zsrandom4(CONST ZVALUE seed,
			 CONST ZVALUE ip, CONST ZVALUE iq, long trials);
E_FUNC RANDOM *zsetrandom(CONST RANDOM *state);
E_FUNC void zrandomskip(long count);
E_FUNC void zrandom(long count, ZVALUE *res);
E_FUNC void zrandom(long count, ZVALUE *res);
E_FUNC void zrandomrange(CONST ZVALUE low, CONST ZVALUE beyond, ZVALUE *res);
E_FUNC long irandom(long s);
E_FUNC RANDOM *randomcopy(CONST RANDOM *random);
E_FUNC void randomfree(RANDOM *random);
E_FUNC bool randomcmp(CONST RANDOM *s1, CONST RANDOM *s2);
E_FUNC void randomprint(CONST RANDOM *state, int flags);
E_FUNC void random_libcalc_cleanup(void);


#endif /* !INCLUDE_ZRANDOM_H */
