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engines/got/musicdriver_adlib.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 GOT_MUSICDRIVER_ADLIB_H
+#define GOT_MUSICDRIVER_ADLIB_H
+
+#include "got/musicdriver.h"
+
+#include "common/scummsys.h"
+#include "common/timer.h"
+#include "audio/fmopl.h"
+
+namespace Got {
+
+class MusicDriver_Got_AdLib : public MusicDriver_Got {
+public:
+	/**
+	 * The number of available channels on the OPL2 chip.
+	 */
+	static const uint8 OPL2_NUM_CHANNELS = 9;
+
+	/**
+	 * OPL operator base registers.
+	 */
+	static const uint8 OPL_REGISTER_BASE_FREQMULT_MISC = 0x20;
+	static const uint8 OPL_REGISTER_BASE_LEVEL = 0x40;
+	static const uint8 OPL_REGISTER_BASE_DECAY_ATTACK = 0x60;
+	static const uint8 OPL_REGISTER_BASE_RELEASE_SUSTAIN = 0x80;
+	static const uint8 OPL_REGISTER_BASE_WAVEFORMSELECT = 0xE0;
+
+	/**
+	 * OPL channel base registers.
+	 */
+	static const uint8 OPL_REGISTER_BASE_FNUMLOW = 0xA0;
+	static const uint8 OPL_REGISTER_BASE_FNUMHIGH_BLOCK_KEYON = 0xB0;
+	static const uint8 OPL_REGISTER_BASE_CONNECTION_FEEDBACK_PANNING = 0xC0;
+
+	MusicDriver_Got_AdLib(uint8 timerFrequency);
+	~MusicDriver_Got_AdLib();
+
+	int open() override;
+	void close() override;
+
+	void syncSoundSettings() override;
+
+	void send(uint16 b) override;
+	void stopAllNotes() override;
+
+	void setTimerFrequency(uint8 timerFrequency) override;
+
+protected:
+	/**
+	 * Initializes the OPL registers to their default values.
+	 */
+	void initOpl();
+
+	void recalculateVolumes();
+	uint8 calculateVolume(uint8 channel, uint8 operatorNum);
+	/**
+	 * Determines if volume settings should be applied to the operator level.
+	 * This depends on the type of the operator (carrier or modulator), which
+	 * depends on the type of connection specified on the channel.
+	 *
+	 * @param oplChannel The OPL channel
+	 * @param operatorNum The number of the operator (0-1)
+	 * @return True if volume should be applied, false otherwise
+	 */
+	bool isVolumeApplicableToOperator(uint8 oplChannel, uint8 operatorNum);
+	/**
+	 * Determines the offset from a base register for the specified operator of
+	 * the specified OPL channel.
+	 * Add the offset to the base register to get the correct register for this
+	 * operator and channel.
+	 *
+	 * @param oplChannel The OPL channel for which to determine the offset.
+	 * @param operatorNum The operator for which to determine the offset (0-1).
+	 * @return The offset to the base register for this operator.
+	 */
+	uint16 determineOperatorRegisterOffset(uint8 oplChannel, uint8 operatorNum);
+	void writeRegister(uint8 oplRegister, uint8 value);
+
+	// The OPL emulator / hardware interface.
+	OPL::OPL *_opl;
+
+	// Last written value to the operator 0 level register for each channel.
+	uint8 _channelOp0LevelRegisterValues[OPL2_NUM_CHANNELS];
+	// Last written value to the operator 1 level register for each channel.
+	uint8 _channelOp1LevelRegisterValues[OPL2_NUM_CHANNELS];
+	// Last written value to the F-num high / block / key on register for each
+	// channel, with the key on bit cleared.
+	uint8 _channelBxRegisterValues[OPL2_NUM_CHANNELS];
+	// Last written value of the connection bit for each channel.
+	uint8 _channelConnectionValues[OPL2_NUM_CHANNELS];
+
+	// User volume settings.
+	uint16 _userMusicVolume;
+	bool _userMute;
+};
+
+} // namespace Got
+
+#endif