SoftwareSerial.h

/*
 * SoftwareSerial.h (formerly NewSoftSerial.h)
 *
 * Multi-instance software serial library for Arduino/Wiring
 * -- Interrupt-driven receive and other improvements by ladyada
 *    (http://ladyada.net)
 * -- Tuning, circular buffer, derivation from class Print/Stream,
 *    multi-instance support, porting to 8MHz processors,
 *    various optimizations, PROGMEM delay tables, inverse logic and
 *    direct port writing by Mikal Hart (http://www.arduiniana.org)
 * -- Pin change interrupt macros by Paul Stoffregen (http://www.pjrc.com)
 * -- 20MHz processor support by Garrett Mace (http://www.macetech.com)
 * -- ATmega1280/2560 support by Brett Hagman (http://www.roguerobotics.com/)
 * -- SAMD51 support by Giuliano Zaro
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * The latest version of this library can always be found at
 * http://arduiniana.org.
 */

#ifndef SOFTWARESERIAL_H
#define SOFTWARESERIAL_H

#include <Arduino.h>
#include <stdint.h>
#include <Stream.h>

/******************************************************************************
* Definitions
******************************************************************************/

#define _SS_MAX_RX_BUFF 64 // RX buffer size

class SoftwareSerial : public Stream {
  private:
    // per object data
    int16_t _receivePin;
    int16_t _transmitPin;
    uint32_t _speed;

    uint16_t _buffer_overflow:1;
    uint16_t _inverse_logic:1;
    uint16_t _half_duplex:1;
    uint16_t _output_pending:1;

    unsigned char _receive_buffer[_SS_MAX_RX_BUFF];
    volatile uint8_t _receive_buffer_tail;
    volatile uint8_t _receive_buffer_head;

    uint32_t delta_start;

    // static data
    static bool initialised;
    static SoftwareSerial * active_listener;
    static SoftwareSerial * volatile active_out;
    static SoftwareSerial * volatile active_in;
    static int32_t tx_tick_cnt;
    static int32_t rx_tick_cnt;
    static uint32_t tx_buffer;
    static int32_t tx_bit_cnt;
    static uint32_t rx_buffer;
    static int32_t rx_bit_cnt;
    static uint32_t cur_speed;

    // private methods
    void send();
    void recv();
    void setTX();
    void setRX();
    void setSpeed(uint32_t speed);
    void setRXTX(bool input);

  public:
    // public methods

    SoftwareSerial(int16_t receivePin, int16_t transmitPin, bool inverse_logic = false);
    ~SoftwareSerial();
    void begin(long speed);
    bool listen();
    void end();
    bool isListening() { return active_listener == this; }
    bool stopListening();
    bool overflow() { bool ret = _buffer_overflow; if (ret) _buffer_overflow = false; return ret; }
    int peek();

    virtual size_t write(uint8_t byte);
    virtual int read();
    virtual int available();
    virtual void flush();
    operator bool() { return true; }

    // public only for easy access by interrupt handlers
    [[gnu::always_inline]] static inline void handle_interrupt();
};

// Arduino 0012 workaround
#undef int
#undef char
#undef long
#undef byte
#undef float
#undef abs
#undef round

#endif // SOFTWARESERIAL_H