CLK/Components/SN76489/SN76489.hpp

//
//  SN76489.hpp
//  Clock Signal
//
//  Created by Thomas Harte on 26/02/2018.
//  Copyright 2018 Thomas Harte. All rights reserved.
//

#pragma once

#include "../../Outputs/Speaker/Implementation/BufferSource.hpp"
#include "../../Concurrency/AsyncTaskQueue.hpp"

namespace TI {

class SN76489: public Outputs::Speaker::BufferSource<SN76489, false> {
public:
	enum class Personality {
		SN76489,
		SN76494,
		SMS
	};

	/// Creates a new SN76489.
	SN76489(Personality, Concurrency::AsyncTaskQueue<false> &, int additional_divider = 1);

	/// Writes a new value to the SN76489.
	void write(uint8_t);

	// As per SampleSource.
	template <Outputs::Speaker::Action action>
	void apply_samples(std::size_t number_of_samples, Outputs::Speaker::MonoSample *target);
	bool is_zero_level() const;
	void set_sample_volume_range(std::int16_t range);

private:
	int master_divider_ = 0;
	int master_divider_period_ = 16;
	int16_t output_volume_ = 0;
	void evaluate_output_volume();
	int volumes_[16];

	Concurrency::AsyncTaskQueue<false> &task_queue_;

	struct ToneChannel {
		// Programmatically-set state; updated by the processor.
		uint16_t divider = 0;
		uint8_t volume = 0xf;

		// Active state; self-evolving as a function of time.
		uint16_t counter = 0;
		int level = 0;
	} channels_[4];
	enum {
		Periodic15,
		Periodic16,
		Noise15,
		Noise16
	} noise_mode_ = Periodic15;
	uint16_t noise_shifter_ = 0;
	int active_register_ = 0;

	bool shifter_is_16bit_ = false;
};

}