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Diffstat (limited to 'common/random.cpp')
-rw-r--r-- | common/random.cpp | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/common/random.cpp b/common/random.cpp new file mode 100644 index 0000000000..9fd9c33e30 --- /dev/null +++ b/common/random.cpp @@ -0,0 +1,59 @@ +/* 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. + * + * $URL$ + * $Id$ + */ + +#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; +} + +uint RandomSource::getRandomNumber(uint max) { + _randSeed = 0xDEADBF03 * (_randSeed + 1); + _randSeed = (_randSeed >> 13) | (_randSeed << 19); + return _randSeed % (max + 1); +} + +uint RandomSource::getRandomBit() { + _randSeed = 0xDEADBF03 * (_randSeed + 1); + _randSeed = (_randSeed >> 13) | (_randSeed << 19); + return _randSeed & 1; +} + +uint RandomSource::getRandomNumberRng(uint min, uint max) { + return getRandomNumber(max - min) + min; +} + +} // End of namespace Common |