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engines/darkseed/adlib_worx.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 DARKSEED_ADLIB_WORX_H
+#define DARKSEED_ADLIB_WORX_H
+
+#include "audio/adlib_ms.h"
+
+namespace Darkseed {
+
+/**
+ * Implementation of the AdLib code from the Worx Toolkit library,
+ * based on version 2.1, as used by Dark Seed (CD version).
+ * Implements the OPL channel allocation algorithm and note frequency
+ * and volume calculation.
+ *
+ * TODO Implementation is incomplete, because Dark Seed does not use
+ * some functionality of the library:
+ * - OPL rhythm mode
+ * - Transpose controllers 0x68 and 0x69 (seems to be buggy)
+ */
+class MidiDriver_Worx_AdLib : public MidiDriver_ADLIB_Multisource {
+private:
+	/**
+	 * The OPL instrument bank of the Worx Toolkit.
+	 * This was taken from the Dark Seed executable and might have been
+	 * customized for the game.
+	 */
+	static const AdLibIbkInstrumentDefinition WORX_INSTRUMENT_BANK[];
+	/**
+	 * The OPL frequency (F-num) for each octave note.
+	 */
+	static const uint16 OPL_NOTE_FREQUENCIES[];
+
+public:
+	MidiDriver_Worx_AdLib(OPL::Config::OplType oplType, int timerFrequency = OPL::OPL::kDefaultCallbackFrequency);
+	~MidiDriver_Worx_AdLib();
+
+protected:
+	uint8 allocateOplChannel(uint8 channel, uint8 source, InstrumentInfo &instrumentInfo) override;
+	uint16 calculateFrequency(uint8 channel, uint8 source, uint8 note) override;
+	uint8 calculateUnscaledVolume(uint8 channel, uint8 source, uint8 velocity, const OplInstrumentDefinition &instrumentDef, uint8 operatorNum) override;
+};
+
+} // namespace Darkseed
+
+#endif // DARKSEED_ADLIB_WORX_H