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75 lines
1.8 KiB
C++
75 lines
1.8 KiB
C++
//
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// KonamiSCC.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 06/01/2018.
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// Copyright 2018 Thomas Harte. All rights reserved.
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//
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#ifndef KonamiSCC_hpp
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#define KonamiSCC_hpp
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#include "../../Outputs/Speaker/Implementation/SampleSource.hpp"
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#include "../../Concurrency/AsyncTaskQueue.hpp"
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namespace Konami {
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/*!
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Provides an emulation of Konami's Sound Creative Chip ('SCC').
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The SCC is a primitive wavetable synthesis chip, offering 32-sample tables,
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and five channels of output. The original SCC uses the same wave for channels
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four and five, the SCC+ supports different waves for the two channels.
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*/
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class SCC: public ::Outputs::Speaker::SampleSource {
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public:
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/// Creates a new SCC.
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SCC(Concurrency::AsyncTaskQueue<false> &task_queue);
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/// As per ::SampleSource; provides a broadphase test for silence.
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bool is_zero_level() const;
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/// As per ::SampleSource; provides audio output.
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void get_samples(std::size_t number_of_samples, std::int16_t *target);
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void set_sample_volume_range(std::int16_t range);
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static constexpr bool get_is_stereo() { return false; }
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/// Writes to the SCC.
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void write(uint16_t address, uint8_t value);
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/// Reads from the SCC.
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uint8_t read(uint16_t address);
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private:
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Concurrency::AsyncTaskQueue<false> &task_queue_;
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// State from here on down is accessed ony from the audio thread.
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int master_divider_ = 0;
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std::int16_t master_volume_ = 0;
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int16_t transient_output_level_ = 0;
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struct Channel {
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int period = 0;
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int amplitude = 0;
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int tone_counter = 0;
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int offset = 0;
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} channels_[5];
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struct Wavetable {
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std::uint8_t samples[32];
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} waves_[4];
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std::uint8_t channel_enable_ = 0;
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void evaluate_output_volume();
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// This keeps a copy of wave memory that is accessed from the
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// main emulation thread.
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std::uint8_t ram_[128];
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};
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}
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#endif /* KonamiSCC_hpp */
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