io/io.hpp

#pragma once

#include <stdint.h>

#include <avr/io.h>

//////////////////////////////////////////////////////////////////////////
// Preprocessor defines

#define GPIO_32 \
	defined(__AVR_ATmega32__) || defined(__AVR_ATmega32A__) || defined(__AVR_ATmega644P__) || \
	    defined(__AVR_ATmega1284P__)
#define GPIO_23 \
	defined(__AVR_ATmega8__) || defined(__AVR_ATmega8A__) || defined(__AVR_ATmega168A__) || defined(__AVR_ATmega328P__)
#define GPIO_6 defined(__AVR_ATtiny13A__) || defined(__AVR_ATtiny85__)

#define HARDWARE_TOGGLE \
	defined(__AVR_ATmega644P__) || defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega168A__) || \
	    defined(__AVR_ATmega328P__) || defined(__AVR_ATtiny13A__) || defined(__AVR_ATtiny85__)

#define PORT_A_AVAILABLE GPIO_32
#define PORT_B_AVAILABLE GPIO_32 || GPIO_23 || GPIO_6
#define PORT_C_AVAILABLE GPIO_32 || GPIO_23
#define PORT_D_AVAILABLE GPIO_32 || GPIO_23

#define PIN_B6_AVAILABLE GPIO_32 || GPIO_23
#define PIN_B7_AVAILABLE GPIO_32 || GPIO_23
#define PIN_C7_AVAILABLE GPIO_32

#define FORCE_INLINE __attribute__((always_inline))

//////////////////////////////////////////////////////////////////////////
// Library implementation

namespace io {

enum class Dir { IN, OUT };

enum class P {
#if PORT_A_AVAILABLE
	A0 = 0x00,
	A1 = 0x01,
	A2 = 0x02,
	A3 = 0x03,
	A4 = 0x04,
	A5 = 0x05,
	A6 = 0x06,
	A7 = 0x07,
#endif

#if PORT_B_AVAILABLE
	B0 = 0x10,
	B1 = 0x11,
	B2 = 0x12,
	B3 = 0x13,
	B4 = 0x14,
	B5 = 0x15,
#if PIN_B6_AVAILABLE
	B6 = 0x16,
#endif
#if PIN_B7_AVAILABLE
	B7 = 0x17,
#endif
#endif

#if PORT_C_AVAILABLE
	C0 = 0x20,
	C1 = 0x21,
	C2 = 0x22,
	C3 = 0x23,
	C4 = 0x24,
	C5 = 0x25,
	C6 = 0x26,
#if PIN_C7_AVAILABLE
	C7 = 0x27,
#endif
#endif

#if PORT_D_AVAILABLE
	D0 = 0x30,
	D1 = 0x31,
	D2 = 0x32,
	D3 = 0x33,
	D4 = 0x34,
	D5 = 0x35,
	D6 = 0x36,
	D7 = 0x37,
#endif
};

enum class Bus {
#if PORT_A_AVAILABLE
	A = 0x00,
#endif
#if PORT_B_AVAILABLE
	B = 0x01,
#endif
#if PORT_C_AVAILABLE
	C = 0x02,
#endif
#if PORT_D_AVAILABLE
	D = 0x03,
#endif
};

//////////////////////////////////////////////////////////////////////////
// Implementation details

namespace detail {

#if PORT_A_AVAILABLE
static constexpr volatile uint8_t *PORT_A_DIR_REG = &DDRA;
static constexpr volatile uint8_t *PORT_A_OUTPUT_REG = &PORTA;
static constexpr volatile uint8_t *PORT_A_INPUT_REG = &PINA;
#else
static constexpr volatile uint8_t *PORT_A_DIR_REG = nullptr;
static constexpr volatile uint8_t *PORT_A_OUTPUT_REG = nullptr;
static constexpr volatile uint8_t *PORT_A_INPUT_REG = nullptr;
#endif

#if PORT_B_AVAILABLE
static constexpr volatile uint8_t *PORT_B_DIR_REG = &DDRB;
static constexpr volatile uint8_t *PORT_B_OUTPUT_REG = &PORTB;
static constexpr volatile uint8_t *PORT_B_INPUT_REG = &PINB;
#else
static constexpr volatile uint8_t *PORT_B_DIR_REG = nullptr;
static constexpr volatile uint8_t *PORT_B_OUTPUT_REG = nullptr;
static constexpr volatile uint8_t *PORT_B_INPUT_REG = nullptr;
#endif

#if PORT_C_AVAILABLE
static constexpr volatile uint8_t *PORT_C_DIR_REG = &DDRC;
static constexpr volatile uint8_t *PORT_C_OUTPUT_REG = &PORTC;
static constexpr volatile uint8_t *PORT_C_INPUT_REG = &PINC;
#else
static constexpr volatile uint8_t *PORT_C_DIR_REG = nullptr;
static constexpr volatile uint8_t *PORT_C_OUTPUT_REG = nullptr;
static constexpr volatile uint8_t *PORT_C_INPUT_REG = nullptr;
#endif

#if PORT_D_AVAILABLE
static constexpr volatile uint8_t *PORT_D_DIR_REG = &DDRD;
static constexpr volatile uint8_t *PORT_D_OUTPUT_REG = &PORTD;
static constexpr volatile uint8_t *PORT_D_INPUT_REG = &PIND;
#else
static constexpr volatile uint8_t *PORT_D_DIR_REG = nullptr;
static constexpr volatile uint8_t *PORT_D_OUTPUT_REG = nullptr;
static constexpr volatile uint8_t *PORT_D_INPUT_REG = nullptr;
#endif

static constexpr auto getBus(const P pin)
{
	// Upper 4 bits of pin encode which port this pin is on
	uint8_t port = static_cast<uint8_t>(pin) >> 4 & 0x0F;
	return static_cast<Bus>(port);
}

static constexpr auto getPin(const P pin)
{
	// Lower 4 bits of pin encode which pin bit it is
	uint8_t pinBit = static_cast<uint8_t>(pin) & 0x0F;
	return pinBit;
}

static constexpr auto getDDR(const Bus bus)
{
	switch (static_cast<uint8_t>(bus)) {
	case 0: // Bus::A
		return PORT_A_DIR_REG;
	case 1: // Bus::B
		return PORT_B_DIR_REG;
	case 2: // Bus::C
		return PORT_C_DIR_REG;
	case 3: // Bus::D
		return PORT_D_DIR_REG;
	}
}

static constexpr auto getPORT(const Bus bus)
{
	switch (static_cast<uint8_t>(bus)) {
	case 0: // Bus::A
		return PORT_A_OUTPUT_REG;
	case 1: // Bus::B
		return PORT_B_OUTPUT_REG;
	case 2: // Bus::C
		return PORT_C_OUTPUT_REG;
	case 3: // Bus::D
		return PORT_D_OUTPUT_REG;
	}
}

static constexpr auto getPIN(const Bus bus)
{
	switch (static_cast<uint8_t>(bus)) {
	case 0: // Bus::A
		return PORT_A_INPUT_REG;
	case 1: // Bus::B
		return PORT_B_INPUT_REG;
	case 2: // Bus::C
		return PORT_C_INPUT_REG;
	case 3: // Bus::D
		return PORT_D_INPUT_REG;
	}
}

} // namespace detail

//////////////////////////////////////////////////////////////////////////
// Zero overhead Pin object for pretty code without losing performance

template <P pin>
class Pin {
  public:
	// Pin objects cannot be moved or copied
	Pin(const Pin &) = delete;
	Pin(Pin &&) = delete;
	Pin &operator=(const Pin &) = delete;
	Pin &operator=(Pin &&) = delete;

	// The only valid way to create a Pin object is with the default constructor
	Pin() = default;

	static inline void dir(const Dir dir) FORCE_INLINE
	{
		constexpr auto bus = detail::getBus(pin);
		constexpr auto dirReg = detail::getDDR(bus);
		constexpr auto pinBit = detail::getPin(pin);

		if (dir == Dir::IN)
			*dirReg &= ~(1 << pinBit);
		else if (dir == Dir::OUT)
			*dirReg |= (1 << pinBit);
	}

	static inline void pullup(const bool enable) FORCE_INLINE
	{
		constexpr auto bus = detail::getBus(pin);
		constexpr auto portReg = detail::getPORT(bus);
		constexpr auto pinBit = detail::getPin(pin);

		if (enable)
			*portReg |= (1 << pinBit);
		else
			*portReg &= ~(1 << pinBit);
	}

	static inline void write(const bool value) FORCE_INLINE
	{
		constexpr auto bus = detail::getBus(pin);
		constexpr auto portReg = detail::getPORT(bus);
		constexpr auto pinBit = detail::getPin(pin);

		if (value)
			*portReg |= (1 << pinBit);
		else
			*portReg &= ~(1 << pinBit);
	}

	static inline void toggle() FORCE_INLINE
	{
#if HARDWARE_TOGGLE
		constexpr auto bus = detail::getBus(pin);
		constexpr auto pinReg = detail::getPIN(bus);
		constexpr auto pinBit = detail::getPin(pin);

		*pinReg |= (1 << pinBit);
#else
		constexpr auto bus = detail::getBus(pin);
		constexpr auto portReg = detail::getPORT(bus);
		constexpr auto pinBit = detail::getPin(pin);

		*portReg ^= (1 << pinBit);
#endif
	}

	static inline bool read() FORCE_INLINE
	{
		constexpr auto bus = detail::getBus(pin);
		constexpr auto pinReg = detail::getPIN(bus);
		constexpr auto pinBit = detail::getPin(pin);

		if (*pinReg >> pinBit & 1)
			return true;

		return false;
	}

	Pin &operator=(const bool value) FORCE_INLINE
	{
		write(value);
		return *this;
	}

	operator bool() const FORCE_INLINE
	{
		return read();
	}
};

//////////////////////////////////////////////////////////////////////////
// Zero overhead Port object for pretty code without losing performance

template <Bus port>
class Port {
  public:
	// Port objects cannot be moved or copied
	Port(const Port &) = delete;
	Port(Port &&) = delete;
	Port &operator=(const Port &) = delete;
	Port &operator=(Port &&) = delete;

	// The only valid way to create a Port object is with the default constructor
	Port() = default;

	static inline void dir(const Dir dir) FORCE_INLINE
	{
		constexpr auto dirReg = detail::getDDR(port);

		if (dir == Dir::IN)
			*dirReg = 0x00;
		else if (dir == Dir::OUT)
			*dirReg = 0xFF;
	}

	static inline void pullup(const bool enable) FORCE_INLINE
	{
		constexpr auto portReg = detail::getPORT(port);

		if (enable)
			*portReg = 0xFF;
		else
			*portReg = 0x00;
	}

	static inline void write(const uint8_t value) FORCE_INLINE
	{
		constexpr auto portReg = detail::getPORT(port);

		*portReg = value;
	}

	static inline void invert() FORCE_INLINE
	{
#if HARDWARE_TOGGLE
		constexpr auto pinReg = detail::getPIN(port);

		*pinReg = 0xFF;
#else
		constexpr auto portReg = detail::getPORT(port);

		*portReg = ~(*portReg);
#endif
	}

	static inline uint8_t read() FORCE_INLINE
	{
		constexpr auto pinReg = detail::getPIN(port);

		return *pinReg;
	}

	inline Port &operator=(const uint8_t value) FORCE_INLINE
	{
		write(value);
		return *this;
	}

	inline operator uint8_t() const FORCE_INLINE
	{
		return read();
	}
};

} // namespace io

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

#undef GPIO_32
#undef GPIO_23
#undef GPIO_6

#undef PORT_A_AVAILABLE
#undef PORT_B_AVAILABLE
#undef PORT_C_AVAILABLE
#undef PORT_D_AVAILABLE

#undef PIN_B6_AVAILABLE
#undef PIN_B7_AVAILABLE
#undef PIN_C7_AVAILABLE

#undef FORCE_INLINE