text: /*
    TwoWire.h - TWI/I2C library for Arduino & Wiring
    Copyright (c) 2006 Nicholas Zambetti.  All right reserved.
  
    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
  
    Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
    Modified December 2014 by Ivan Grokhotkov (ivan@esp8266.com) - esp8266 support
    Modified April 2015 by Hrsto Gochkov (ficeto@ficeto.com) - alternative esp8266 support
    Modified November 2017 by Chuck Todd <stickbreaker on GitHub> to use ISR and increase stability.
  */
  
  #ifndef TwoWire_h
  #define TwoWire_h
  
  #include <esp32-hal.h>
  #include "freertos/FreeRTOS.h"
  #include "freertos/queue.h"
  #include "Stream.h"
  
  #define STICKBREAKER 'V1.1.0'
  #ifndef I2C_BUFFER_LENGTH
  #define I2C_BUFFER_LENGTH 256
  #endif
  typedef void(*user_onRequest)(void);
  typedef void(*user_onReceive)(uint8_t*, int);
  
  class TwoWire: public Stream
  {
  protected:
      uint8_t num;
      int8_t sda;
      int8_t scl;
      i2c_t * i2c;
  
      uint8_t rxBuffer[I2C_BUFFER_LENGTH];
      uint16_t rxIndex;
      uint16_t rxLength;
      uint16_t rxQueued; //@stickBreaker
  
      uint8_t txBuffer[I2C_BUFFER_LENGTH];
      uint16_t txIndex;
      uint16_t txLength;
      uint16_t txAddress;
      uint16_t txQueued; //@stickbreaker
  
      uint8_t transmitting;
      /* slave Mode, not yet Stickbreaker
              static user_onRequest uReq[2];
              static user_onReceive uRcv[2];
          void onRequestService(void);
          void onReceiveService(uint8_t*, int);
      */
      i2c_err_t last_error; // @stickBreaker from esp32-hal-i2c.h
      uint16_t _timeOutMillis;
  
  public:
      TwoWire(uint8_t bus_num);
      ~TwoWire();
      bool begin(int sda=-1, int scl=-1, uint32_t frequency=0); // returns true, if successful init of i2c bus
        // calling will attemp to recover hung bus
  
      void setClock(uint32_t frequency); // change bus clock without initing hardware
      size_t getClock(); // current bus clock rate in hz
  
      void setTimeOut(uint16_t timeOutMillis); // default timeout of i2c transactions is 50ms
      uint16_t getTimeOut();
  
      uint8_t lastError();
      char * getErrorText(uint8_t err);
  
      //@stickBreaker for big blocks and ISR model
      i2c_err_t writeTransmission(uint16_t address, uint8_t* buff, uint16_t size, bool sendStop=true);
      i2c_err_t readTransmission(uint16_t address, uint8_t* buff, uint16_t size, bool sendStop=true, uint32_t *readCount=NULL);
  
      void beginTransmission(uint16_t address);
      void beginTransmission(uint8_t address);
      void beginTransmission(int address);
  
      uint8_t endTransmission(bool sendStop);
      uint8_t endTransmission(void);
  
      uint8_t requestFrom(uint16_t address, uint8_t size, bool sendStop);
      uint8_t requestFrom(uint16_t address, uint8_t size, uint8_t sendStop);
      uint8_t requestFrom(uint16_t address, uint8_t size);
      uint8_t requestFrom(uint8_t address, uint8_t size, uint8_t sendStop);
      uint8_t requestFrom(uint8_t address, uint8_t size);
      uint8_t requestFrom(int address, int size, int sendStop);
      uint8_t requestFrom(int address, int size);
  
      size_t write(uint8_t);
      size_t write(const uint8_t *, size_t);
      int available(void);
      int read(void);
      int peek(void);
      void flush(void);
  
      inline size_t write(const char * s)
      {
          return write((uint8_t*) s, strlen(s));
      }
      inline size_t write(unsigned long n)
      {
          return write((uint8_t)n);
      }
      inline size_t write(long n)
      {
          return write((uint8_t)n);
      }
      inline size_t write(unsigned int n)
      {
          return write((uint8_t)n);
      }
      inline size_t write(int n)
      {
          return write((uint8_t)n);
      }
  
      void onReceive( void (*)(int) );
      void onRequest( void (*)(void) );
  
      uint32_t setDebugFlags( uint32_t setBits, uint32_t resetBits);
      bool busy();
  };
  
  extern TwoWire Wire;
  extern TwoWire Wire1;
  
  
  /*
  V1.1.0 08JAN2019 Support CPU Clock frequency changes
  V1.0.2 30NOV2018 stop returning I2C_ERROR_CONTINUE on ReSTART operations, regain compatibility with Arduino libs
  V1.0.1 02AUG2018 First Fix after release, Correct ReSTART handling, change Debug control, change begin()
    to a function, this allow reporting if bus cannot be initialized, Wire.begin() can be used to recover
    a hung bus busy condition.
  V0.2.2 13APR2018 preserve custom SCL,SDA,Frequency when no parameters passed to begin()
  V0.2.1 15MAR2018 Hardware reset, Glitch prevention, adding destructor for second i2c testing
  */
  #endif
  