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29 lines
795 B
C++
29 lines
795 B
C++
//
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// LowFrequencyOscillator.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 23/04/2020.
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// Copyright © 2020 Thomas Harte. All rights reserved.
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//
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#include "LowFrequencyOscillator.hpp"
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using namespace Yamaha::OPL;
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void LowFrequencyOscillator::update() {
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++counter;
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// This produces output of:
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//
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// four instances of 0, four instances of 1... _three_ instances of 26,
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// four instances of 25, four instances of 24... _three_ instances of 0.
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//
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// ... advancing once every 64th update.
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const int tremolo_index = (counter >> 6) % 210;
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const int tremolo_levels[2] = {tremolo_index >> 2, 52 - ((tremolo_index+1) >> 2)};
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tremolo = tremolo_levels[tremolo_index / 107];
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// Vibrato is relatively simple: it's just three bits from the counter.
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vibrato = (counter >> 10) & 7;
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}
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