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67 lines
1.5 KiB
C++
67 lines
1.5 KiB
C++
//
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// SN76489.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 26/02/2018.
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// Copyright 2018 Thomas Harte. All rights reserved.
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//
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#pragma once
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#include "../../Outputs/Speaker/Implementation/SampleSource.hpp"
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#include "../../Concurrency/AsyncTaskQueue.hpp"
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namespace TI {
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class SN76489: public Outputs::Speaker::SampleSource {
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public:
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enum class Personality {
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SN76489,
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SN76494,
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SMS
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};
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/// Creates a new SN76489.
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SN76489(Personality personality, Concurrency::AsyncTaskQueue<false> &task_queue, int additional_divider = 1);
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/// Writes a new value to the SN76489.
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void write(uint8_t value);
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// As per SampleSource.
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void get_samples(std::size_t number_of_samples, std::int16_t *target);
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bool is_zero_level() const;
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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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private:
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int master_divider_ = 0;
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int master_divider_period_ = 16;
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int16_t output_volume_ = 0;
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void evaluate_output_volume();
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int volumes_[16];
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Concurrency::AsyncTaskQueue<false> &task_queue_;
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struct ToneChannel {
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// Programmatically-set state; updated by the processor.
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uint16_t divider = 0;
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uint8_t volume = 0xf;
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// Active state; self-evolving as a function of time.
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uint16_t counter = 0;
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int level = 0;
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} channels_[4];
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enum {
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Periodic15,
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Periodic16,
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Noise15,
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Noise16
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} noise_mode_ = Periodic15;
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uint16_t noise_shifter_ = 0;
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int active_register_ = 0;
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bool shifter_is_16bit_ = false;
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};
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}
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