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de1338787f
Calling RandomSource::getRandomNumber() results in divide by zero exception when called with max = 4294967295 as max + 1 overflows to zero and the subsequent modulus operation causes the exception. Certain game saves in Bladerunner trigger this.
72 lines
2.0 KiB
C++
72 lines
2.0 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 <climits>
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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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setSeed(g_system->getMillis());
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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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