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engines/sludge/timing.cpp

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+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/system.h"
+
+#include "sludge/timing.h"
+
+namespace Sludge {
+
+Timer::Timer(){
+	reset();
+}
+
+void Timer::reset(void) {
+	_desiredFPS = 300;
+	_startTime = 0;
+	_endTime = 0;
+	_desiredFrameTime = 0;
+	_addNextTime = 0;
+
+	// FPS stats
+	_lastFPS = -1;
+	_thisFPS = -1;
+	_lastSeconds = 0;
+}
+
+void Timer::init(void) {
+	_desiredFrameTime = 1000 / _desiredFPS;
+	_startTime = g_system->getMillis();
+}
+
+void Timer::initSpecial(int t) {
+	_desiredFrameTime = 1000 / t;
+	_startTime = g_system->getMillis();
+}
+
+void Timer::updateFpsStats() {
+	uint32 currentSeconds = g_system->getMillis() / 1000;
+	if (_lastSeconds != currentSeconds) {
+		_lastSeconds = currentSeconds;
+		_lastFPS = _thisFPS;
+		_thisFPS = 1;
+	} else {
+		++_thisFPS;
+	}
+}
+
+void Timer::waitFrame(void) {
+	uint32 timetaken;
+
+	for (;;) {
+		_endTime = g_system->getMillis();
+		timetaken = _addNextTime + _endTime - _startTime;
+		if (timetaken >= _desiredFrameTime)
+			break;
+		g_system->delayMillis(1);
+	}
+
+	_addNextTime = timetaken - _desiredFrameTime;
+	if (_addNextTime > _desiredFrameTime)
+		_addNextTime = _desiredFrameTime;
+
+	_startTime = _endTime;
+
+	// Stats
+	updateFpsStats();
+}
+
+} // End of namespace Sludge