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engines/ultima/nuvie/sound/mididrv_m_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 NUVIE_SOUND_MIDIDRV_M_ADLIB_H
+#define NUVIE_SOUND_MIDIDRV_M_ADLIB_H
+
+#include "audio/adlib_ms.h"
+
+namespace Ultima {
+namespace Nuvie {
+
+/**
+ * M driver for AdLib (OPL2).
+ * This driver supports several effects by adjusting OPL frequency and level
+ * values based on timer ticks: slide, vibrato and fade in/out. Only vibrato is
+ * used by the tracks in Ultima 6.
+ */
+class MidiDriver_M_AdLib : public MidiDriver_ADLIB_Multisource {
+protected:
+	// The direction of a volume fade: in (increase) or out (decrease).
+	enum FadeDirection {
+		FADE_DIRECTION_NONE,
+		FADE_DIRECTION_FADE_IN,
+		FADE_DIRECTION_FADE_OUT
+	};
+
+	// The current direction of vibrato pitch change.
+	enum VibratoDirection {
+		VIBRATO_DIRECTION_RISING,
+		VIBRATO_DIRECTION_FALLING
+	};
+
+	// Converts M note values to OPL frequency (F-num) values.
+	static const uint16 FNUM_VALUES[24];
+
+public:
+	MidiDriver_M_AdLib();
+	~MidiDriver_M_AdLib();
+
+	using MidiDriver_Multisource::send;
+	void send(int8 source, uint32 b) override;
+	void metaEvent(int8 source, byte type, const byte *data, uint16 length) override;
+
+protected:
+	void programChange(uint8 channel, uint8 program, uint8 source) override;
+	void modulation(uint8 channel, uint8 modulation, uint8 source) override;
+
+	uint8 allocateOplChannel(uint8 channel, uint8 source, InstrumentInfo &instrumentInfo) override;
+	void writeFrequency(uint8 oplChannel, OplInstrumentRhythmType rhythmType = RHYTHM_TYPE_UNDEFINED) override;
+	uint16 calculateFrequency(uint8 channel, uint8 source, uint8 note) override;
+	uint8 calculateUnscaledVolume(uint8 channel, uint8 source, uint8 velocity, const OplInstrumentDefinition &instrumentDef, uint8 operatorNum) override;
+	void writeVolume(uint8 oplChannel, uint8 operatorNum, OplInstrumentRhythmType rhythmType = RHYTHM_TYPE_UNDEFINED) override;
+
+	void deinitSource(uint8 source) override;
+
+	void onTimer() override;
+
+	// Number of F-num units each channel will increase/decrease each tick.
+	int8 _slideValues[9];
+	// Maximum number of F-num units the frequency will be changed by vibrato,
+	// before applying the factor, for each channel. This is the difference
+	// between the lowest and highest value (so twice the amplitude).
+	uint8 _vibratoDepths[9];
+	// Multiplication factor for vibrato F-num values for each channel.
+	uint8 _vibratoFactors[9];
+	// The current "progression" of vibrato through the cycle for each channel.
+	// This is before the vibrato factor is applied.
+	uint8 _vibratoCurrentDepths[9];
+	// The current direction in which the vibrato is progressing for each
+	// channel (rising or falling frequency).
+	VibratoDirection _vibratoDirections[9];
+	// The direction of the fade currently active on each channel (in or out).
+	// NONE indicates no fade is active.
+	FadeDirection _fadeDirections[9];
+	// The delay in ticks between each level increase or decrease for each
+	// channel.
+	uint8 _fadeStepDelays[9];
+	// The current fade delay counter value for each channel.
+	uint8 _fadeCurrentDelays[9];
+};
+
+} // End of namespace Nuvie
+} // End of namespace Ultima
+
+#endif