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engines/bagel/boflib/cache.h

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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/>.
+ *
+ */
+
+#ifndef BAGEL_BOFLIB_CACHE_H
+#define BAGEL_BOFLIB_CACHE_H
+
+#include "bagel/boflib/llist.h"
+#include "bagel/boflib/stdinc.h"
+
+namespace Bagel {
+
+class CCache : private CLList {
+private:
+	virtual bool alloc() = 0;       // These pure-virtuals MUST be defined
+	virtual void free() = 0;        // in the derived class.
+
+	static CCache *_pCacheList;    // Linked cache list
+	static uint32 _lOldest;        // Current oldest object in cache
+	static uint32 _lYoungest;      // Current youngest object in cache
+	static uint16 _nEntries;       // Number of CCache Objects
+
+	uint32 _lAge;      // Age of this object
+	int _nLockCount;   // # of locks held on this object
+	bool _bCached;     // true if object is in the cache
+
+	bool _bValid;      // true if this object is valid
+
+public:
+	/**
+	 * Constructor
+	 */
+	CCache();
+
+	/**
+	 * Destructor
+	 */
+	virtual ~CCache();
+
+	/**
+	 * Loads current object into cache
+	 */
+	void load();
+
+	/**
+	 * Releases current object from cache
+	 */
+	bool release();
+
+	void lock() {
+		_nLockCount++;
+		load();
+	}
+	void unlock() {
+		_nLockCount--;
+	}
+	bool isLocked() {
+		return (_nLockCount > 0);
+	}
+
+	/**
+	 * initialize statics
+	*/
+	static void initialize();
+
+	/**
+	 * Releases all objects from cache
+	 */
+	static bool flush();
+
+	/**
+	 * Releases older objects from cache if need memory
+	 * @remarks     Optimizes cache so that the specified amount of memory is left available.
+	 * @param lRequestedFreeSpace   Free space requested to remain available
+	 * @return      true if there were any objects to release from the cache.
+	 *              false if there were no objects released.
+	 */
+	static bool optimize(uint32 lRequestedFreeSpace);
+};
+
+} // namespace Bagel
+
+#endif