zephyrSerial.h

/*
 * Copyright (c) 2022 Dhruva Gole
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#pragma once

#include <zephyr/sys/ring_buffer.h>
#include <api/HardwareSerial.h>

namespace arduino {

class ZephyrSerialStub : public HardwareSerial
{
public:
	void begin(__attribute__((unused)) unsigned long baudRate) { }
	void begin(__attribute__((unused)) unsigned long baudrate, __attribute__((unused)) uint16_t config) { }
	void end() { }
	int available() { return 0; }
	int peek() { return 0; }
	int read() { return 0; }
	void flush() { }
	size_t write(const uint8_t data)
	{
		printk("%c", static_cast<char>(data));
		return 1;
	}

	operator bool() { return true; }
};

class ZephyrSerial : public HardwareSerial
{
public:
	template <int SZ>
	class ZephyrSerialBuffer
	{
		friend arduino::ZephyrSerial;
		struct ring_buf ringbuf;
		uint8_t buffer[SZ];
		struct k_sem sem;

		ZephyrSerialBuffer()
		{
			k_sem_init(&sem, 1, 1);
			ring_buf_init(&ringbuf, sizeof(buffer), buffer);
		}
	};

	ZephyrSerial(const struct device *dev) : uart(dev) { }
	void begin(unsigned long baudrate, uint16_t config);
	void begin(unsigned long baudrate) { begin(baudrate, SERIAL_8N1); }
	void flush();
	void end() { }
	size_t write(const uint8_t *buffer, size_t size);
	size_t write(const uint8_t data) { return write(&data, 1); }
	using Print::write; // pull in write(str) and write(buf, size) from Print
	int available();
  	int availableForWrite();
	int peek();
	int read();

	operator bool()
	{
		return true;
	}

	friend class SerialUSB_;

protected:
	void IrqHandler();
	static void IrqDispatch(const struct device *dev, void *data);

	const struct device *uart;
	ZephyrSerialBuffer<CONFIG_ARDUINO_API_SERIAL_BUFFER_SIZE> tx;
	ZephyrSerialBuffer<CONFIG_ARDUINO_API_SERIAL_BUFFER_SIZE> rx;
};


}   // namespace arduino

#if DT_NODE_HAS_PROP(DT_PATH(zephyr_user), serials)
#if !DT_NODE_HAS_PROP(DT_PATH(zephyr_user), cdc_acm)
// If CDC USB, use that object as Serial (and SerialUSB)
extern arduino::ZephyrSerial Serial;
#endif
#if (DT_PROP_LEN(DT_PATH(zephyr_user), serials) > 1)
#define SERIAL_DEFINED_0		 1
#define EXTERN_SERIAL_N(i)		 extern arduino::ZephyrSerial Serial##i;
#define DECLARE_EXTERN_SERIAL_N(n, p, i) COND_CODE_1(SERIAL_DEFINED_##i, (), (EXTERN_SERIAL_N(i)))

/* Declare Serial1, Serial2, ... */
DT_FOREACH_PROP_ELEM(DT_PATH(zephyr_user), serials, DECLARE_EXTERN_SERIAL_N)

#undef DECLARE_EXTERN_SERIAL_N
#undef EXTERN_SERIAL_N
#undef SERIAL_DEFINED_0
#endif
#elif DT_NODE_HAS_STATUS(DT_NODELABEL(arduino_serial), okay)
extern arduino::ZephyrSerial Serial;
#else
extern arduino::ZephyrSerialStub Serial;
#endif