uart/hardware0.hpp

#pragma once

#include "config.hpp"

#define FORCE_INLINE __attribute__((always_inline))

namespace uart {

enum class Mode {
	ASYNCHRONOUS,
	ASYNCHRONOUS_2X,
	SYNCHRONOUS_MASTER,
	SYNCHRONOUS_SLAVE,
	SPI,
};

enum class Driven {
	INTERRUPT,
	BLOCKING,
};

namespace detail {

#if defined(__AVR_ATmega1284P__)

struct Registers0 {
	static constexpr volatile auto *IO_REG = &UDR0;
	static constexpr volatile auto *CTRL_STAT_REG_A = &UCSR0A;
	static constexpr volatile auto *CTRL_STAT_REG_B = &UCSR0B;
	static constexpr volatile auto *CTRL_STAT_REG_C = &UCSR0C;
	static constexpr volatile auto *BAUD_REG_L = &UBRR0L;
	static constexpr volatile auto *BAUD_REG_H = &UBRR0H;
};

static constexpr auto getLastRxError() {}
static constexpr void set2xSpeed() {}

template <uint16_t BaudVal>
static inline void setBaudRate()
{
	*Registers0::BAUD_REG_H = static_cast<uint8_t>(BaudVal >> 8);
	*Registers0::BAUD_REG_L = static_cast<uint8_t>(BaudVal);
}

template <uint8_t RegVal>
static inline void setCtrlStatRegC()
{
	*Registers0::CTRL_STAT_REG_C = RegVal;
}

#else
#error "This chip is not supported"
#endif

} // namespace detail

template <Mode mode = Mode::ASYNCHRONOUS, class cfg = Config<>, Driven driven = Driven::INTERRUPT>
class Hardware0 {
  public:
	using data_t = typename cfg::data_t;
	static constexpr auto DATA_BITS = cfg::DATA_BITS;

	static void init()
	{
		detail::setBaudRate<calcBaud()>();

		constexpr auto dataBitsVal = calcDataBits();
		constexpr auto parityVal = calcParity();
		constexpr auto stopBitsVal = calcStopBits();
		constexpr auto modeVal = calcMode();
		constexpr auto enableRx = calcRxState<true>();
		constexpr auto enableTx = calcTxState<true>();

		constexpr uint8_t controlRegB = dataBitsVal.regBVal | enableRx | enableTx;
		constexpr uint8_t controlRegC = dataBitsVal.regCVal | parityVal | stopBitsVal | modeVal;

		*detail::Registers0::CTRL_STAT_REG_B = controlRegB;
		detail::setCtrlStatRegC<controlRegC>();
	}

	static void txByte(data_t byte) FORCE_INLINE
	{
		while (!(*detail::Registers0::CTRL_STAT_REG_A & (1 << UDRE0)))
			;

		*detail::Registers0::IO_REG = byte;
	}

	static data_t rxByte() {}

	static data_t peek() {}

  private:
	static constexpr auto BAUD_RATE = cfg::BAUD_RATE;
	static constexpr auto PARITY = cfg::PARITY;
	static constexpr auto STOP_BITS = cfg::STOP_BITS;

	static constexpr auto calcBaud()
	{
		// The actual formula is (F_CPU / (16 * baudRate)) - 1, but this one has the advantage of rounding correctly
		constexpr auto baudVal = (F_CPU + 8 * BAUD_RATE) / (16 * BAUD_RATE) - 1;
		return baudVal;
	}

	struct DataBitsVal {
		uint8_t regCVal = 0;
		uint8_t regBVal = 0;
	};

	static constexpr auto calcDataBits()
	{
		DataBitsVal dataBitsVal;

		switch (DATA_BITS) {
		case DataBits::FIVE:
			dataBitsVal.regCVal = 0;
			break;
		case DataBits::SIX:
			dataBitsVal.regCVal = (1 << UCSZ00);
			break;
		case DataBits::SEVEN:
			dataBitsVal.regCVal = (1 << UCSZ01);
			break;
		case DataBits::EIGHT:
			dataBitsVal.regCVal = (1 << UCSZ01) | (1 << UCSZ00);
			break;
		case DataBits::NINE:
			dataBitsVal.regCVal = (1 << UCSZ01) | (1 << UCSZ00);
			dataBitsVal.regBVal = (1 << UCSZ02);
			break;
		}

		return dataBitsVal;
	}

	static constexpr auto calcParity()
	{
		uint8_t parityVal = 0;

		if (PARITY == Parity::EVEN)
			parityVal = (1 << UPM01);
		else if (PARITY == Parity::ODD)
			parityVal = (1 << UPM01) | (1 << UPM00);

		return parityVal;
	}

	static constexpr auto calcStopBits()
	{
		uint8_t stopBitsVal = 0;

		if (STOP_BITS == StopBits::TWO)
			stopBitsVal = (1 << USBS0);

		return stopBitsVal;
	}

	static constexpr auto calcMode()
	{
		static_assert(mode != Mode::SPI, "SPI mode can not be used with uart");

		uint8_t modeVal = 0;

		if (mode == Mode::SYNCHRONOUS_MASTER || mode == Mode::SYNCHRONOUS_SLAVE) {
			modeVal = (1 << UMSEL00);
		}

		return modeVal;
	}

	template <bool enable>
	static constexpr auto calcRxState()
	{
		uint8_t enableVal = 0;

		if (enable)
			enableVal = (1 << RXEN0);

		return enableVal;
	}

	template <bool enable>
	static constexpr auto calcTxState()
	{
		uint8_t enableVal = 0;

		if (enable)
			enableVal = (1 << TXEN0);

		return enableVal;
	}
};

} // namespace uart

#undef FORCE_INLINE