COMMON: Move Common::RandomSource to common/random.*

svn-id: r48279

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