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Diffstat (limited to 'audio/softsynth/mt32/LegacyWaveGenerator.h')
| -rw-r--r-- | audio/softsynth/mt32/LegacyWaveGenerator.h | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/audio/softsynth/mt32/LegacyWaveGenerator.h b/audio/softsynth/mt32/LegacyWaveGenerator.h new file mode 100644 index 0000000000..81c1b9c713 --- /dev/null +++ b/audio/softsynth/mt32/LegacyWaveGenerator.h @@ -0,0 +1,146 @@ +/* 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 { + +/** + * 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 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 |