src/mt32/LegacyWaveGenerator.h

/* Copyright (C) 2003, 2004, 2005, 2006, 2008, 2009 Dean Beeler, Jerome Fisher
 * Copyright (C) 2011, 2012, 2013 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/>.
 */

#if MT32EMU_ACCURATE_WG == 1

#ifndef MT32EMU_LA32_WAVE_GENERATOR_H
#define MT32EMU_LA32_WAVE_GENERATOR_H

namespace MT32Emu {

class LA32WaveGenerator {
        //***************************************************************************
        //  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;

        // Logarithmic amp of the wave generator
        Bit32u amp;

        // Logarithmic frequency of the resulting wave
        Bit16u pitch;

        // 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;

        // Composed of the base cutoff in range [78..178] left-shifted by 18 bits and the TVF modifier
        Bit32u cutoffVal;

        // 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;
};

// LA32PartialPair contains a structure of two partials being mixed / ring modulated
class LA32PartialPair {
        LA32WaveGenerator master;
        LA32WaveGenerator slave;
        bool ringModulated;
        bool mixed;
        float masterOutputSample;
        float slaveOutputSample;

public:
        enum PairType {
                MASTER,
                SLAVE
        };

        // 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
        Bit16s nextOutSample();

        // Deactivate the WG engine
        void deactivate(const PairType master);

        // Return active state of the WG engine
        bool isActive(const PairType master) const;
};

} // namespace MT32Emu

#endif // #ifndef MT32EMU_LA32_WAVE_GENERATOR_H

#endif // #if MT32EMU_ACCURATE_WG == 1