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random.cpp

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL: https://scummvm.svn.sourceforge.net/svnroot/scummvm/scummvm/tags/release-1-2-0/common/random.cpp $
 * $Id: random.cpp 48279 2010-03-18 15:07:11Z fingolfin $
 */

#include "common/random.h"
#include "common/system.h"


namespace Common {

RandomSource::RandomSource() {
      // Use system time as RNG seed. Normally not a good idea, if you are using
      // a RNG for security purposes, but good enough for our purposes.
      assert(g_system);
      uint32 seed = g_system->getMillis();
      setSeed(seed);
}

void RandomSource::setSeed(uint32 seed) {
      _randSeed = seed;
}

00043 uint RandomSource::getRandomNumber(uint max) {
      _randSeed = 0xDEADBF03 * (_randSeed + 1);
      _randSeed = (_randSeed >> 13) | (_randSeed << 19);
      return _randSeed % (max + 1);
}

00049 uint RandomSource::getRandomBit() {
      _randSeed = 0xDEADBF03 * (_randSeed + 1);
      _randSeed = (_randSeed >> 13) | (_randSeed << 19);
      return _randSeed & 1;
}

00055 uint RandomSource::getRandomNumberRng(uint min, uint max) {
      return getRandomNumber(max - min) + min;
}

}     // End of namespace Common

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