d439655643
This improves the range of seeds compared to using only getMillis (which is the number of milliseconds since program start) as the seed. This was especially an issue if you started the game directly from command line, Steam, or GOG instead of using the ScummVM interface. Previously the initial seed was just the load time, which can have very small variance on a fast computer.
77 lines
2.3 KiB
C++
77 lines
2.3 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#include <limits.h>
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#include "common/random.h"
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#include "common/system.h"
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#include "gui/EventRecorder.h"
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namespace Common {
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RandomSource::RandomSource(const String &name) {
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// Use system time as RNG seed. Normally not a good idea, if you are using
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// a RNG for security purposes, but good enough for our purposes.
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assert(g_system);
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#ifdef ENABLE_EVENTRECORDER
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setSeed(g_eventRec.getRandomSeed(name));
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#else
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TimeDate time;
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g_system->getTimeAndDate(time);
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uint32 newSeed = time.tm_sec + time.tm_min * 60 + time.tm_hour * 3600;
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newSeed += time.tm_mday * 86400 + time.tm_mon * 86400 * 31;
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newSeed += time.tm_year * 86400 * 366;
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newSeed = newSeed * 1000 + g_system->getMillis();
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setSeed(newSeed);
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#endif
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}
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void RandomSource::setSeed(uint32 seed) {
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_randSeed = seed;
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}
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uint RandomSource::getRandomNumber(uint max) {
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_randSeed = 0xDEADBF03 * (_randSeed + 1);
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_randSeed = (_randSeed >> 13) | (_randSeed << 19);
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if (max == UINT_MAX)
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return _randSeed;
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return _randSeed % (max + 1);
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}
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uint RandomSource::getRandomBit() {
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_randSeed = 0xDEADBF03 * (_randSeed + 1);
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_randSeed = (_randSeed >> 13) | (_randSeed << 19);
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return _randSeed & 1;
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}
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uint RandomSource::getRandomNumberRng(uint min, uint max) {
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return getRandomNumber(max - min) + min;
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}
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int RandomSource::getRandomNumberRngSigned(int min, int max) {
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return getRandomNumber(max - min) + min;
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}
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} // End of namespace Common
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