uart/hardware0.hpp

#pragma once

#include <cstdint>

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

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

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.
The _SFR_ADDR macro in sfr_defs.h would give the address, but it does that by taking the address of the dereferenced
pointer and casts it to uint16_t, which is still not a legal constexpr.
The workaround therefore is to disable the pointer cast and dereference macro _MMIO_BYTE temporarily.
*/

#pragma push_macro("_MMIO_BYTE")
#undef _MMIO_BYTE
#define _MMIO_BYTE

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

#pragma pop_macro("_MMIO_BYTE")

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

#if defined(__AVR_ATmega328P__)
#define USART0_RX_vect USART_RX_vect
#define USART0_UDRE_vect USART_UDRE_vect
#endif

#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 detail::BlockingHardware<detail::Registers0, detail::ControlFlagsA0, detail::ControlFlagsB0,
                                                  detail::ControlFlagsC0, cfg, mode> {
};

template <class cfg, Mode mode>
class Hardware0<cfg, Driven::INTERRUPT, mode>
    : public detail::InterruptHardware<detail::Registers0, detail::ControlFlagsA0, detail::ControlFlagsB0,
                                       detail::ControlFlagsC0, cfg, mode> {
  public:
	[[gnu::always_inline]] static void init()
	{
		HardwareImpl::init();
		sei();
	}

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

	using InterruptHardwareImpl = detail::InterruptHardware<detail::Registers0, detail::ControlFlagsA0,
	                                                        detail::ControlFlagsB0, detail::ControlFlagsC0, cfg, mode>;

	// Must be friends with Uart interface to call these private handlers
	template <class Driver>
	friend class Uart;

	[[gnu::always_inline]] static void rxIntHandler()
	{
		InterruptHardwareImpl::rxIntHandler();
	}

	[[gnu::always_inline]] static void dataRegEmptyIntHandler()
	{
		InterruptHardwareImpl::dataRegEmptyIntHandler();
	}
};

} // namespace uart

//////////////////////////////////////////////////////////////////////////

// Forward declare interrupt functions to allow adding them as friends
extern "C" {
void USART0_RX_vect() __attribute__((signal));
void USART0_UDRE_vect() __attribute__((signal));
}

// clang-format off
#define REGISTER_UART0_INT_VECTORS(uart_type) \
	ISR(USART0_RX_vect)                       \
	{                                         \
		uart_type::rxIntHandler();            \
	}                                         \
	ISR(USART0_UDRE_vect)                     \
	{                                         \
		uart_type::dataRegEmptyIntHandler();  \
	}                                         \
	struct _##uart_type {}
// clang-format on