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7367750823
* Renamed lmms_basics.h to LmmsTypes.h and scoped it down for that purpose. * Shifted the LMMS_STRINGIFY macro to it's own header. * Removed the debug.h header file and use cmake to handle the macro logic. * Remove some unused headers and include directives
59 lines
2.5 KiB
C++
59 lines
2.5 KiB
C++
/*
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* OscillatorConstants.h - declaration of constants used in Oscillator and SampleBuffer
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* for band limited wave tables
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*
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* Copyright (c) 2018 Dave French <dave/dot/french3/at/googlemail/dot/com>
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*
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* This file is part of LMMS - https://lmms.io
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program (see COPYING); if not, write to the
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* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301 USA.
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*
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*/
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#ifndef LMMS_OSCILLATORCONSTANTS_H
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#define LMMS_OSCILLATORCONSTANTS_H
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#include <array>
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#include "LmmsTypes.h"
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namespace lmms::OscillatorConstants
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{
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// Limit wavetables to the audible audio spectrum
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const int MAX_FREQ = 20000;
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// Minimum size of table to have all audible bands for midi note 1 (i.e. 20 000 Hz / 8.176 Hz)
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constexpr int WAVETABLE_LENGTH = static_cast<int>(MAX_FREQ / 8.176);
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//SEMITONES_PER_TABLE, the smaller the value the smoother the harmonics change on frequency sweeps
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// with the trade off of increased memory requirements to store the wave tables
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// require memory = NumberOfWaveShapes*WAVETABLE_LENGTH*(MidiNoteCount/SEMITONES_PER_TABLE)*BytePerSample_t
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// 7*2446*(128/1)*4 = 8766464 bytes
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const int SEMITONES_PER_TABLE = 1;
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const int WAVE_TABLES_PER_WAVEFORM_COUNT = 128 / SEMITONES_PER_TABLE;
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// There is some ambiguity around the use of "wavetable", "wavetable synthesis" or related terms.
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// The following meanings and definitions were selected for use in the Oscillator class:
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// - wave shape: abstract and precise definition of the graph associated with a given type of wave;
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// - waveform: digital representations the wave shape, a set of waves optimized for use at varying pitches;
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// - wavetable: a table containing one period of a wave, with frequency content optimized for a specific pitch.
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using wavetable_t = std::array<sample_t, WAVETABLE_LENGTH>;
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using waveform_t = std::array<wavetable_t, WAVE_TABLES_PER_WAVEFORM_COUNT>;
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} // namespace lmms::OscillatorConstants
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#endif // LMMS_OSCILLATORCONSTANTS_H
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