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/**
* @author Adam McLaurin
* @date September 2006
*/
/*
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifndef _SOCKET_RandomNumber_H
#define _SOCKET_RandomNumber_H
#include "sockets-config.h"
#include <limits>
#ifdef SOCKETS_NAMESPACE
namespace SOCKETS_NAMESPACE {
#endif
/**
* The following class uses an xorshift algorithm proposed in the following
* paper:
* - http://www.jstatsoft.org/v08/i14/xorshift.pdf
*
* The algorithm provides a PRNG with a period of (2^128)-1
*
* This PRNG is *not* intended for cryptographic purposes
*/
class RandomNumber
{
public:
/**
* Default constructor
*
* NOTE: Internal seeds are set to defaults proposed by the paper
*/
RandomNumber(bool time_shuffle = false);
/**
* Custom constructor
*
* @param x_seed X seed
*
* @param y_seed Y seed
*
* @param z_seed Z seed
*
* @param w_seed W seed
*/
RandomNumber(
unsigned long int x_seed,
unsigned long int y_seed,
unsigned long int z_seed,
unsigned long int w_seed);
/**
* Destructor
*/
~RandomNumber();
// public methods
/**
* Reset internal state to initial seed values
*/
void reset();
/**
* Cast operator to obtain current random value in the PRNG
*
* @return Current random value in the PRNG
*/
operator unsigned long int() const;
/**
* Go to the next number in the PRNG sequence
*
* NOTE: This method is a slightly modified implementation of the xor128()
* function proposed in the paper
*
* @return Next value produced by the PRNG (after updating)
*/
unsigned long int next();
/**
* Skip ahead in the PRNG sequence by a given number of iterations
*
* @param s Number of iterations to skip ahead
*
* @return Value produced by the PRNG after skipping ahead in the sequence
*/
unsigned long int skip(unsigned long int s);
/**
* Obtain all the initial seeds for this PRNG
*
* @param x_seed X seed (output)
*
* @param y_seed Y seed (output)
*
* @param z_seed Z seed (output)
*
* @param w_seed W seed (output)
*/
void getSeed(
unsigned long int& x_seed,
unsigned long int& y_seed,
unsigned long int& z_seed,
unsigned long int& w_seed);
/**
* Get the maximum possible random number from this PRNG
*
* @return Maximum possible random number from this PRNG
*/
static unsigned long int max_random();
// public constants
/**
* Default x-seed as proposed by the paper
*/
static const unsigned long int X_SEED_DEFAULT;
/**
* Default y-seed as proposed by the paper
*/
static const unsigned long int Y_SEED_DEFAULT;
/**
* Default z-seed as proposed by the paper
*/
static const unsigned long int Z_SEED_DEFAULT;
/**
* Default w-seed as proposed by the paper
*/
static const unsigned long int W_SEED_DEFAULT;
private:
/**
* X seed
*/
unsigned long int mXSeed;
/**
* Y seed
*/
unsigned long int mYSeed;
/**
* Z seed
*/
unsigned long int mZSeed;
/**
* W seed
*/
unsigned long int mWSeed;
/**
* X value
*/
unsigned long int mX;
/**
* Y value
*/
unsigned long int mY;
/**
* Z value
*/
unsigned long int mZ;
/**
* W value
*
* NOTE: This is the externally-visible next value produced by the PRNG
*/
unsigned long int mW;
};
#ifdef SOCKETS_NAMESPACE
} // namespace SOCKETS_NAMESPACE {
#endif
#endif // _SOCKETS_RandomNumber_H
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