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engines/agos/drivers/accolade/cms.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 AGOS_DRIVERS_ACCOLADE_CMS_H
+#define AGOS_DRIVERS_ACCOLADE_CMS_H
+
+#include "audio/mididrv.h"
+
+#include "audio/cms.h"
+
+namespace AGOS {
+
+// MIDI driver for the Creative Music System / Gameblaster.
+// This driver uses only 6 of the available 12 channels and does not support
+// stereo. It only supports note on and off and program change; the selected
+// instrument only affects the note volume.
+class MidiDriver_Accolade_Cms : public MidiDriver {
+protected:
+	static const byte REGISTER_BASE_AMPLITUDE = 0x00;
+	static const byte REGISTER_BASE_FREQUENCY = 0x08;
+	static const byte REGISTER_BASE_OCTAVE = 0x10;
+	static const byte REGISTER_FREQUENCY_ENABLE = 0x14;
+	static const byte REGISTER_RESET_SOUND_ENABLE = 0x1C;
+
+	// Frequency register values for octave notes.
+	static const byte CMS_NOTE_FREQUENCIES[12];
+	// Volume adjustments for all instruments.
+	static const byte CMS_VOLUME_ADJUSTMENTS[128];
+
+public:
+	MidiDriver_Accolade_Cms();
+	~MidiDriver_Accolade_Cms() override;
+
+	int open() override;
+	void close() override;
+	bool isOpen() const override;
+	uint32 getBaseTempo() override;
+	// This driver does not support MidiChannel objects.
+	MidiChannel *allocateChannel() override;
+	// This driver does not support MidiChannel objects.
+	MidiChannel *getPercussionChannel() override;
+
+	using MidiDriver::send;
+	void send(uint32 b) override;
+
+	void setTimerCallback(void *timer_param, Common::TimerManager::TimerProc timer_proc) override;
+	void onTimer();
+
+protected:
+	void cmsInit();
+
+	void noteOff(uint8 channel, uint8 note);
+	void noteOn(uint8 channel, uint8 note, uint8 velocity);
+	void programChange(uint8 channel, uint8 instrument);
+	void controlChange(uint8 channel, uint8 controller, uint8 value);
+
+	// Returns the value for the frequency enable register of the first CMS
+	// chip based on the _activeNotes array (if a note is active, the bit for
+	// the corresponding channel is set).
+	byte determineFrequencyEnableRegisterValue();
+	void writeRegister(uint16 reg, uint8 value);
+
+	CMS::CMS *_cms;
+	bool _isOpen;
+
+	// The selected instrument on each MIDI channel.
+	byte _instruments[16];
+	// The active note on each CMS channel (0xFF if no note is active).
+	byte _activeNotes[12];
+	// The current values of the CMS octave registers (0x10 - 0x12).
+	byte _octaveRegisterValues[6];
+
+	// External timer callback
+	void *_timer_param;
+	Common::TimerManager::TimerProc _timer_proc;
+};
+
+} // End of namespace AGOS
+
+#endif