/*******************************************************************************
 * util/bdrandom.h                                                             *
 *                                                                             *
 * BitDHT: An Flexible DHT library.                                            *
 *                                                                             *
 * Copyright (C) 2010 Cyril Soler <csoler@users.sourceforge.net>               *
 *                                                                             *
 * This program is free software: you can redistribute it and/or modify        *
 * it under the terms of the GNU Affero General Public License as              *
 * published by the Free Software Foundation, either version 3 of the          *
 * License, or (at your option) any later version.                             *
 *                                                                             *
 * This program 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 Affero General Public License for more details.                         *
 *                                                                             *
 * You should have received a copy of the GNU Affero General Public License    *
 * along with this program. If not, see <https://www.gnu.org/licenses/>.       *
 *                                                                             *
 *******************************************************************************/
#ifndef BITDHT_UTILS_BDRANDOM_H
#define BITDHT_UTILS_BDRANDOM_H

/* This Source Code is basically a direct copy of libretroshare's RsRandom.
 * the function names have just been renamed. drbob
 */

// bdRandom contains a random number generator that is
// - thread safe
// - system independant
// - fast
// - NOT CRYPTOGRAPHICALLY SAFE
// - DO NOT USE FOR ANYTHING REQUIRING STRONG UNPREDICTABLE RANDOMNESS
//
// The implementation is adapted from the Mersenne Twister page of Wikipedia.
//
// 		http://en.wikipedia.org/wiki/Mersenne_twister

// FIXME(ben): MT is not cryptographically safe.

#include <vector>
#include "util/bdthreads.h"

class bdRandom
{
	public:
		static uint32_t random_u32() ;
		static uint64_t random_u64() ;
		static float 	 random_f32() ;
		static double	 random_f64() ;

		static bool     seed(uint32_t s) ;

		static std::string random_alphaNumericString(uint32_t length) ; 

	private:
		static bdMutex rndMtx ;

		static const uint32_t N = 624;
		static const uint32_t M = 397;

		static const uint32_t MATRIX_A 	= 0x9908b0dfUL;
		static const uint32_t UMASK 		= 0x80000000UL;
		static const uint32_t LMASK 		= 0x7fffffffUL;

		static void locked_next_state() ;
		static uint32_t index ;
		static std::vector<uint32_t> MT ;
};

#endif