Marlin_Firmware/Marlin/src/HAL/STM32/SoftwareSerial.h

/**
 * SoftwareSerial.h (formerly NewSoftSerial.h)
 *
 * Multi-instance software serial library for Arduino/Wiring
 * -- Interrupt-driven receive and other improvements by ladyada
 *    (https://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 (https://www.pjrc.com)
 * -- 20MHz processor support by Garrett Mace (http://www.macetech.com)
 * -- ATmega1280/2560 support by Brett Hagman (https://www.roguerobotics.com/)
 *
 * 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.
 */
#pragma once

#include <Arduino.h>

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

#define _SS_MAX_RX_BUFF 64 // RX buffer size

class SoftwareSerial : public Stream {
  private:
    // per object data
    uint16_t _receivePin;
    uint16_t _transmitPin;
    GPIO_TypeDef *_receivePinPort;
    uint32_t _receivePinNumber;
    GPIO_TypeDef *_transmitPinPort;
    uint32_t _transmitPinNumber;
    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 = 0;

    // static data
    static HardwareTimer timer;
    static const IRQn_Type timer_interrupt_number;
    static uint32_t timer_interrupt_priority;
    static SoftwareSerial *active_listener;
    static SoftwareSerial *volatile active_out;
    static SoftwareSerial *volatile active_in;
    static int32_t tx_tick_cnt;
    static volatile 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);
    static void handleInterrupt(HardwareTimer *timer);

  public:
    // public methods

    SoftwareSerial(uint16_t receivePin, uint16_t transmitPin, bool inverse_logic=false);
    virtual ~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; }

    static void setInterruptPriority(uint32_t preemptPriority, uint32_t subPriority);

    using Print::write;
};