CLK/Components/I2C/I2C.hpp

//
//  I2C.hpp
//  Clock Signal
//
//  Created by Thomas Harte on 16/03/2024.
//  Copyright © 2024 Thomas Harte. All rights reserved.
//

#pragma once

#include <cstdint>
#include <optional>
#include <unordered_map>

namespace I2C {

/// Provides the virtual interface for an I2C peripheral; attaching this to a bus
/// provides automatic protocol handling.
struct Peripheral {
	virtual void start([[maybe_unused]] bool is_read) {}
	virtual void stop() {}
	virtual std::optional<uint8_t> read() { return std::nullopt; }
	virtual void write(uint8_t) {}
};

class Bus {
public:
	void set_data(bool pulled);
	bool data();

	void set_clock(bool pulled);
	bool clock();

	void set_clock_data(bool clock_pulled, bool data_pulled);

	void add_peripheral(Peripheral *, int address);

private:
	bool data_ = false;
	bool clock_ = false;
	bool in_bit_ = false;
	std::unordered_map<int, Peripheral *> peripherals_;

	uint16_t input_ = 0xffff;
	int input_count_ = -1;

	Peripheral *active_peripheral_ = nullptr;
	uint16_t peripheral_response_ = 0xffff;
	int peripheral_bits_ = 0;

	enum class Event {
		Zero, One, Start, Stop, FinishedOutput,
	};
	void signal(Event);

	enum class State {
		AwaitingAddress,
		CollectingAddress,

		CompletingWriteAcknowledge,
		AwaitingByteAcknowledge,

		ReceivingByte,
	} state_ = State::AwaitingAddress;
};

}