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audio/fmopl.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 AUDIO_FMOPL_H
+#define AUDIO_FMOPL_H
+
+#include "audio/chip.h"
+
+namespace Audio {
+class SoundHandle;
+}
+
+namespace Common {
+class String;
+}
+
+namespace OPL {
+
+class OPL;
+
+/**
+ * @defgroup audio_fmopl OPL emulation
+ * @ingroup audio
+ *
+ * @brief OPL class for managing an OPS emulator.
+ * @{
+ */
+
+class Config {
+public:
+	enum OplFlags {
+		kFlagOpl2		= (1 << 0),
+		kFlagDualOpl2	= (1 << 1),
+		kFlagOpl3		= (1 << 2)
+	};
+
+	/**
+	 * OPL type to emulate.
+	 */
+	enum OplType {
+		kOpl2,
+		kDualOpl2,
+		kOpl3
+	};
+
+	typedef int8 DriverId;
+	struct EmulatorDescription {
+		const char *name;
+		const char *description;
+
+		DriverId id;	// A unique ID for each driver
+		uint32 flags;	// Capabilities of this driver
+	};
+
+	/**
+	 * Get a list of all available OPL emulators.
+	 * @return list of all available OPL emulators, terminated by a zero entry
+	 */
+	static const EmulatorDescription *getAvailable() { return _drivers; }
+
+	/**
+	 * Returns the driver id of a given name.
+	 */
+	static DriverId parse(const Common::String &name);
+
+	/**
+	 * @return The driver description for the given id or 0 in case it is not
+	 *         available.
+	 */
+	static const EmulatorDescription *findDriver(DriverId id);
+
+	/**
+	 * Detects a driver for the specific type.
+	 *
+	 * @return Returns a valid driver id on success, -1 otherwise.
+	 */
+	static DriverId detect(OplType type);
+
+	/**
+	 * Creates the specific driver with a specific type setup.
+	 */
+	static OPL *create(DriverId driver, OplType type);
+
+	/**
+	 * Wrapper to easily init an OPL chip, without specifing an emulator.
+	 * By default it will try to initialize an OPL2 emulator, thus an AdLib card.
+	 */
+	static OPL *create(OplType type = kOpl2);
+
+private:
+	static const EmulatorDescription _drivers[];
+};
+
+/**
+ * A representation of a Yamaha OPL chip.
+ */
+class OPL : virtual public Audio::Chip {
+private:
+	static bool _hasInstance;
+public:
+	OPL();
+	virtual ~OPL() { _hasInstance = false; }
+
+	/**
+	 * Initializes the OPL emulator.
+	 *
+	 * @return		true on success, false on failure
+	 */
+	virtual bool init() = 0;
+
+	/**
+	 * Reinitializes the OPL emulator
+	 */
+	virtual void reset() = 0;
+
+	/**
+	 * Writes a byte to the given I/O port.
+	 *
+	 * @param a		port address
+	 * @param v		value, which will be written
+	 */
+	virtual void write(int a, int v) = 0;
+
+	/**
+	 * Function to directly write to a specific OPL register.
+	 * This writes to *both* chips for a Dual OPL2. We allow
+	 * writing to secondary OPL registers by using register
+	 * values >= 0x100.
+	 *
+	 * @param r		hardware register number to write to
+	 * @param v		value, which will be written
+	 */
+	virtual void writeReg(int r, int v) = 0;
+
+	using Audio::Chip::start;
+	void start(TimerCallback *callback) { start(callback, kDefaultCallbackFrequency); }
+
+	enum {
+		/**
+		 * The default callback frequency that start() uses
+		 */
+		kDefaultCallbackFrequency = 250
+	};
+
+protected:
+	/**
+	 * Initializes an OPL3 chip for emulating dual OPL2.
+	 * 
+	 * @param oplType The type of OPL configuration that the engine expects.
+	 * If this is not DualOpl2, this function will do nothing.
+	 */
+	void initDualOpl2OnOpl3(Config::OplType oplType);
+
+	/**
+	 * Processes the specified register write so it will be correctly handled
+	 * for emulating dual OPL2 on an OPL3 chip.
+	 * 
+	 * @param r The register that is written to.
+	 * @param v The value written to the register.
+	 * @param oplType The type of OPL configuration that the engine expects.
+	 * If this is not DualOpl2, this function will do nothing.
+	 * @return True if the register write can be processed normally; false if
+	 * it should be discarded. In this case, a new call to writeReg is usually
+	 * performed by this function to replace the discarded register write.
+	*/
+	bool emulateDualOpl2OnOpl3(int r, int v, Config::OplType oplType);
+
+	bool _rhythmMode;
+	int _connectionFeedbackValues[3];
+};
+
+/** @} */
+} // End of namespace OPL
+
+#endif