simple_rng.hpp

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/* $Id: simple_rng.hpp 52533 2012-01-07 02:35:17Z shadowmaster $ */
/*
   Copyright (C) 2003 by David White <dave@whitevine.net>
   Copyright (C) 2005 - 2012 by Yann Dirson <ydirson@altern.org>
   Part of the Battle for Wesnoth Project http://www.wesnoth.org/

   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.

   See the COPYING file for more details.
*/

#ifndef SIMPLE_RNG_HPP_INCLUDED
#define SIMPLE_RNG_HPP_INCLUDED

class config;

namespace rand_rng
{

class simple_rng
{
public:
    simple_rng();
    simple_rng(const config& cfg);

    /** Get a new random number. */
    int get_next_random();

    /**
     *  Seeds the random pool.
     *
     *  @param call_count   Upon loading we need to restore the state at saving
     *                      so set the number of times a random number is
     *                      generated for replays the orginal value is
     *                      required.
     */
    void seed_random(const unsigned call_count = 0);

    /**
     *  Seeds the random pool.
     *
     *  @param seed         The initial value for the random engine.
     *  @param call_count   Upon loading we need to restore the state at saving
     *                      so set the number of times a random number is
     *                      generated for replays the orginal value is
     *                      required.
     */
    void seed_random(const int seed, const unsigned call_count = 0);

    /**
     * Resets the random to the 0 calls and the seed to the random
     *  this way we stay in the same sequence but don't have a lot
     *  calls. Used when moving to the next scenario.
     */
    void rotate_random();

    int get_random_seed() const { return random_seed_; }
    int get_random_calls() const { return random_calls_; }

private:
    /** Initial seed for the pool. */
    int random_seed_;

    /** State for the random pool (modulo arithmetic). */
    unsigned random_pool_;

    /** Number of time a random number is generated. */
    unsigned random_calls_;

    /** Sets the next random number in the pool. */
    void random_next();
};

} // ends rand_rng namespace

#endif