uart/hardware0.hpp

#pragma once

#include <stdint.h>

#include <avr/interrupt.h>
#include <avr/io.h>
#include <avr/sfr_defs.h>

#include "config.hpp"
#include "hardware.hpp"

#define FORCE_INLINE __attribute__((always_inline))

namespace uart {

namespace detail {

#if defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega328P__)

/*
The following works in avr-gcc 5.4.0, but is not legal C++, because ptr's are not legal constexpr's
  constexpr auto *foo = ptr;

Workaround is to store the the address of the ptr in a uintptr_t and reinterpret_cast it at call site
For this to work we need to temporarily disable the _SFR_MEM8 macro so that the register macro just gives the address
*/

#undef _SFR_MEM8
#define _SFR_MEM8

struct Registers0 {
	static constexpr uintptr_t IO_REG_ADDR = UDR0;
	static constexpr uintptr_t CTRL_STAT_REG_A_ADDR = UCSR0A;
	static constexpr uintptr_t CTRL_STAT_REG_B_ADDR = UCSR0B;
	static constexpr uintptr_t CTRL_STAT_REG_C_ADDR = UCSR0C;
	static constexpr uintptr_t BAUD_REG_L_ADDR = UBRR0L;
	static constexpr uintptr_t BAUD_REG_H_ADDR = UBRR0H;
};

#undef _SFR_MEM8
#define _SFR_MEM8(mem_addr) _MMIO_BYTE(mem_addr)

enum class ControlFlagsA0 {
	MULTI_PROC_COMM_MODE = MPCM0,
	SPEED_2X = U2X0,
	PARITY_ERROR = UPE0,
	DATA_OVER_RUN = DOR0,
	FRAME_ERROR = FE0,
	DATA_REG_EMPTY = UDRE0,
	TRANSMIT_COMPLETE = TXC0,
	RECEIVE_COMPLETE = RXC0,
};

enum class ControlFlagsB0 {
	TX_DATA_BIT_8 = TXB80,
	RX_DATA_BIT_8 = RXB80,
	CHAR_SIZE_2 = UCSZ02,
	TX_ENABLE = TXEN0,
	RX_ENABLE = RXEN0,
	DATA_REG_EMPTY_INT_ENABLE = UDRIE0,
	TX_INT_ENABLE = TXCIE0,
	RX_INT_ENABLE = RXCIE0,
};

enum class ControlFlagsC0 {
	CLK_POLARITY = UCPOL0,
	CHAR_SIZE_0 = UCSZ00,
	CHAR_SIZE_1 = UCSZ01,
	STOP_BIT_SEL = USBS0,
	PARITY_MODE_0 = UPM00,
	PARITY_MODE_1 = UPM01,
	MODE_SEL_0 = UMSEL00,
	MODE_SEL_1 = UMSEL01,
};

// clang-format off
constexpr int operator<<(const int &lhs, const ControlFlagsA0 &rhs) { return lhs << static_cast<int>(rhs); }
constexpr int operator<<(const int &lhs, const ControlFlagsB0 &rhs) { return lhs << static_cast<int>(rhs); }
constexpr int operator<<(const int &lhs, const ControlFlagsC0 &rhs) { return lhs << static_cast<int>(rhs); }
// clang-format on

extern void (*fnRx0IntHandler)();
extern void (*fnDataReg0EmptyIntHandler)();

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

} // namespace detail

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

	static void init() FORCE_INLINE
	{
		HardwareImpl::init();
	}

	static void txByte(data_t byte) FORCE_INLINE
	{
		HardwareImpl::txByteBlocking(byte);
	}

	static bool rxByte(data_t &byte) FORCE_INLINE
	{
		return HardwareImpl::rxByteBlocking(byte);
	}

	static bool peek(data_t &byte) FORCE_INLINE
	{
		static_cast<void>(byte);
		static_assert(driven == Driven::BLOCKING, "Peek with data is not supported in blocking mode");
		return false;
	}

	static bool peek() FORCE_INLINE
	{
		return HardwareImpl::peekBlocking();
	}

	static void flushTx() FORCE_INLINE
	{
		while (!HardwareImpl::txEmpty())
			;
		while (!HardwareImpl::txComplete())
			;
		HardwareImpl::clearTxComplete();
	}

  private:
	using HardwareImpl = detail::Hardware<detail::Registers0, detail::ControlFlagsA0, detail::ControlFlagsB0,
	                                      detail::ControlFlagsC0, cfg, driven, mode>;
};

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

	static void init() FORCE_INLINE
	{
		detail::fnRx0IntHandler = rxIntHandler;
		detail::fnDataReg0EmptyIntHandler = dataRegEmptyIntHandler;

		HardwareImpl::init();
		sei();
	}

	static void txByte(const data_t &byte) FORCE_INLINE
	{
		uint8_t tmpHead = (sm_txBuf.head + 1) % TX_BUFFER_SIZE;
		while (tmpHead == sm_txBuf.tail)
			;

		sm_txBuf.buf[tmpHead] = byte;
		sm_txBuf.head = tmpHead;

		HardwareImpl::enableDataRegEmptyInt();
	}

	static bool rxByte(data_t &byte) FORCE_INLINE
	{
		if (sm_rxBuf.head == sm_rxBuf.tail)
			return false;

		uint8_t tmpTail = (sm_rxBuf.tail + 1) % RX_BUFFER_SIZE;
		byte = sm_rxBuf.buf[tmpTail];
		sm_rxBuf.tail = tmpTail;

		return true;
	}

	static bool peek(data_t &byte) FORCE_INLINE
	{
		if (sm_rxBuf.head == sm_rxBuf.tail)
			return false;

		uint8_t tmpTail = (sm_rxBuf.tail + 1) % RX_BUFFER_SIZE;
		byte = sm_rxBuf.buf[tmpTail];

		return true;
	}

	static bool peek() FORCE_INLINE
	{
		return (sm_rxBuf.head != sm_rxBuf.tail);
	}

	static void flushTx() FORCE_INLINE
	{
		while (sm_txBuf.head != sm_txBuf.tail)
			;
		while (!HardwareImpl::txEmpty())
			;
		while (!HardwareImpl::txComplete())
			;
		HardwareImpl::clearTxComplete();
	}

  private:
	using HardwareImpl = detail::Hardware<detail::Registers0, detail::ControlFlagsA0, detail::ControlFlagsB0,
	                                      detail::ControlFlagsC0, cfg, Driven::INTERRUPT, mode>;

	static constexpr auto TX_BUFFER_SIZE = 16;
	static constexpr auto RX_BUFFER_SIZE = 16;

	static volatile detail::RingBuffer<data_t, TX_BUFFER_SIZE> sm_txBuf;
	static volatile detail::RingBuffer<data_t, RX_BUFFER_SIZE> sm_rxBuf;

	static void rxIntHandler()
	{
		auto data = HardwareImpl::rxByteInterrupt();

		uint8_t tmpHead = (sm_rxBuf.head + 1) % RX_BUFFER_SIZE;

		if (tmpHead != sm_rxBuf.tail) {
			sm_rxBuf.head = tmpHead;
			sm_rxBuf.buf[tmpHead] = data;
		} else {
			// TODO: Handle overflow
		}
	}

	static void dataRegEmptyIntHandler() FORCE_INLINE
	{
		if (sm_txBuf.head != sm_txBuf.tail) {
			uint8_t tmpTail = (sm_txBuf.tail + 1) % TX_BUFFER_SIZE;
			sm_txBuf.tail = tmpTail;
			HardwareImpl::txByteInterrupt(sm_txBuf.buf[tmpTail]);
		} else
			HardwareImpl::disableDataRegEmptyInt();
	}
};

template <class cfg, Mode mode>
volatile detail::RingBuffer<typename Hardware0<cfg, Driven::INTERRUPT, mode>::data_t,
                            Hardware0<cfg, Driven::INTERRUPT, mode>::TX_BUFFER_SIZE>
    Hardware0<cfg, Driven::INTERRUPT, mode>::sm_txBuf = {0, 0, {0}};

template <class cfg, Mode mode>
volatile detail::RingBuffer<typename Hardware0<cfg, Driven::INTERRUPT, mode>::data_t,
                            Hardware0<cfg, Driven::INTERRUPT, mode>::RX_BUFFER_SIZE>
    Hardware0<cfg, Driven::INTERRUPT, mode>::sm_rxBuf = {0, 0, {0}};

} // namespace uart

#undef FORCE_INLINE