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audio/softsynth/mt32/LA32FloatWaveGenerator.h

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+/* Copyright (C) 2003, 2004, 2005, 2006, 2008, 2009 Dean Beeler, Jerome Fisher
+ * Copyright (C) 2011-2022 Dean Beeler, Jerome Fisher, Sergey V. Mikayev
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published by
+ *  the Free Software Foundation, either version 2.1 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 Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef MT32EMU_LA32_FLOAT_WAVE_GENERATOR_H
+#define MT32EMU_LA32_FLOAT_WAVE_GENERATOR_H
+
+#include "globals.h"
+#include "internals.h"
+#include "Types.h"
+#include "LA32WaveGenerator.h"
+
+namespace MT32Emu {
+
+/**
+ * LA32WaveGenerator is aimed to represent the exact model of LA32 wave generator.
+ * The output square wave is created by adding high / low linear segments in-between
+ * the rising and falling cosine segments. Basically, it's very similar to the phase distortion synthesis.
+ * Behaviour of a true resonance filter is emulated by adding decaying sine wave.
+ * The beginning and the ending of the resonant sine is multiplied by a cosine window.
+ * To synthesise sawtooth waves, the resulting square wave is multiplied by synchronous cosine wave.
+ */
+class LA32FloatWaveGenerator {
+	//***************************************************************************
+	//  The local copy of partial parameters below
+	//***************************************************************************
+
+	bool active;
+
+	// True means the resulting square wave is to be multiplied by the synchronous cosine
+	bool sawtoothWaveform;
+
+	// Values in range [1..31]
+	// Value 1 correspong to the minimum resonance
+	Bit8u resonance;
+
+	// Processed value in range [0..255]
+	// Values in range [0..128] have no effect and the resulting wave remains symmetrical
+	// Value 255 corresponds to the maximum possible asymmetric of the resulting wave
+	Bit8u pulseWidth;
+
+	// Logarithmic PCM sample start address
+	const Bit16s *pcmWaveAddress;
+
+	// Logarithmic PCM sample length
+	Bit32u pcmWaveLength;
+
+	// true for looped logarithmic PCM samples
+	bool pcmWaveLooped;
+
+	// false for slave PCM partials in the structures with the ring modulation
+	bool pcmWaveInterpolated;
+
+	//***************************************************************************
+	// Internal variables below
+	//***************************************************************************
+
+	float wavePos;
+	float lastFreq;
+	float pcmPosition;
+
+	float getPCMSample(unsigned int position);
+
+public:
+	// Initialise the WG engine for generation of synth partial samples and set up the invariant parameters
+	void initSynth(const bool sawtoothWaveform, const Bit8u pulseWidth, const Bit8u resonance);
+
+	// Initialise the WG engine for generation of PCM partial samples and set up the invariant parameters
+	void initPCM(const Bit16s * const pcmWaveAddress, const Bit32u pcmWaveLength, const bool pcmWaveLooped, const bool pcmWaveInterpolated);
+
+	// Update parameters with respect to TVP, TVA and TVF, and generate next sample
+	float generateNextSample(const Bit32u amp, const Bit16u pitch, const Bit32u cutoff);
+
+	// Deactivate the WG engine
+	void deactivate();
+
+	// Return active state of the WG engine
+	bool isActive() const;
+
+	// Return true if the WG engine generates PCM wave samples
+	bool isPCMWave() const;
+}; // class LA32FloatWaveGenerator
+
+class LA32FloatPartialPair : public LA32PartialPair {
+	LA32FloatWaveGenerator master;
+	LA32FloatWaveGenerator slave;
+	bool ringModulated;
+	bool mixed;
+	float masterOutputSample;
+	float slaveOutputSample;
+
+public:
+	// ringModulated should be set to false for the structures with mixing or stereo output
+	// ringModulated should be set to true for the structures with ring modulation
+	// mixed is used for the structures with ring modulation and indicates whether the master partial output is mixed to the ring modulator output
+	void init(const bool ringModulated, const bool mixed);
+
+	// Initialise the WG engine for generation of synth partial samples and set up the invariant parameters
+	void initSynth(const PairType master, const bool sawtoothWaveform, const Bit8u pulseWidth, const Bit8u resonance);
+
+	// Initialise the WG engine for generation of PCM partial samples and set up the invariant parameters
+	void initPCM(const PairType master, const Bit16s * const pcmWaveAddress, const Bit32u pcmWaveLength, const bool pcmWaveLooped);
+
+	// Update parameters with respect to TVP, TVA and TVF, and generate next sample
+	void generateNextSample(const PairType master, const Bit32u amp, const Bit16u pitch, const Bit32u cutoff);
+
+	// Perform mixing / ring modulation and return the result
+	float nextOutSample();
+
+	// Deactivate the WG engine
+	void deactivate(const PairType master);
+
+	// Return active state of the WG engine
+	bool isActive(const PairType master) const;
+}; // class LA32FloatPartialPair
+
+} // namespace MT32Emu
+
+#endif // #ifndef MT32EMU_LA32_FLOAT_WAVE_GENERATOR_H