c++ - wire.h 外部双线对象错误

Question

我使用 eclipse 为 arduino 制作项目。我将“Wire.h”包含到一个新类中，并且在 arduinocore 库项目中，我在 Wire.h header 处收到错误。错误在于该行76 最后是:

extern TwoWire Wire;

它说

Description Resource Path Location Type The type 'TwoWire' must implement the inherited pure virtual method 'Print::write' Wire.h /ArduinoCore/src line 76 Code Analysis Problem

我给你了.cpp和头文件，它们与arduino ide中的相同。我可以做什么来解决这个问题？

#ifndef TwoWire_h
#define TwoWire_h



#include <inttypes.h>
    #include "Stream.h"

    #define BUFFER_LENGTH 32

    class TwoWire : public Stream
    {
      private:
        static uint8_t rxBuffer[];
        static uint8_t rxBufferIndex;
        static uint8_t rxBufferLength;

        static uint8_t txAddress;
        static uint8_t txBuffer[];
        static uint8_t txBufferIndex;
        static uint8_t txBufferLength;

        static uint8_t transmitting;
        static void (*user_onRequest)(void);
        static void (*user_onReceive)(int);
        static void onRequestService(void);
        static void onReceiveService(uint8_t*, int);
      public:
        TwoWire();
        void begin();
        void begin(uint8_t);
        void begin(int);
        void beginTransmission(uint8_t);
        void beginTransmission(int);
        uint8_t endTransmission(void);
        uint8_t endTransmission(uint8_t);
        uint8_t requestFrom(uint8_t, uint8_t);
        uint8_t requestFrom(uint8_t, uint8_t, uint8_t);
        uint8_t requestFrom(int, int);
        uint8_t requestFrom(int, int, int);
        virtual size_t write(uint8_t);
        virtual size_t write(const uint8_t *, size_t);
        virtual int available(void);
        virtual int read(void);
        virtual int peek(void);
        virtual void flush(void);
        void onReceive( void (*)(int) );
        void onRequest( void (*)(void) );

        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); }
        using Print::write;
    };

    extern TwoWire Wire;

    #endif

和 .cpp 文件:

extern "C" {
  #include <stdlib.h>
  #include <string.h>
  #include <inttypes.h>
  #include "twi.h"
}

#include "Wire.h"

// Initialize Class Variables //////////////////////////////////////////////////

uint8_t TwoWire::rxBuffer[BUFFER_LENGTH];
uint8_t TwoWire::rxBufferIndex = 0;
uint8_t TwoWire::rxBufferLength = 0;

uint8_t TwoWire::txAddress = 0;
uint8_t TwoWire::txBuffer[BUFFER_LENGTH];
uint8_t TwoWire::txBufferIndex = 0;
uint8_t TwoWire::txBufferLength = 0;

uint8_t TwoWire::transmitting = 0;
void (*TwoWire::user_onRequest)(void);
void (*TwoWire::user_onReceive)(int);

// Constructors ////////////////////////////////////////////////////////////////

TwoWire::TwoWire()
{
}

// Public Methods //////////////////////////////////////////////////////////////

void TwoWire::begin(void)
{
  rxBufferIndex = 0;
  rxBufferLength = 0;

  txBufferIndex = 0;
  txBufferLength = 0;

  twi_init();
}

void TwoWire::begin(uint8_t address)
{
  twi_setAddress(address);
  twi_attachSlaveTxEvent(onRequestService);
  twi_attachSlaveRxEvent(onReceiveService);
  begin();
}

void TwoWire::begin(int address)
{
  begin((uint8_t)address);
}

uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint8_t sendStop)
{
  // clamp to buffer length
  if(quantity > BUFFER_LENGTH){
    quantity = BUFFER_LENGTH;
  }
  // perform blocking read into buffer
  uint8_t read = twi_readFrom(address, rxBuffer, quantity, sendStop);
  // set rx buffer iterator vars
  rxBufferIndex = 0;
  rxBufferLength = read;

  return read;
}

uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity)
{
  return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)true);
}

uint8_t TwoWire::requestFrom(int address, int quantity)
{
  return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)true);
}

uint8_t TwoWire::requestFrom(int address, int quantity, int sendStop)
{
  return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)sendStop);
}

void TwoWire::beginTransmission(uint8_t address)
{
  // indicate that we are transmitting
  transmitting = 1;
  // set address of targeted slave
  txAddress = address;
  // reset tx buffer iterator vars
  txBufferIndex = 0;
  txBufferLength = 0;
}

void TwoWire::beginTransmission(int address)
{
  beginTransmission((uint8_t)address);
}

//
//  Originally, 'endTransmission' was an f(void) function.
//  It has been modified to take one parameter indicating
//  whether or not a STOP should be performed on the bus.
//  Calling endTransmission(false) allows a sketch to 
//  perform a repeated start. 
//
//  WARNING: Nothing in the library keeps track of whether
//  the bus tenure has been properly ended with a STOP. It
//  is very possible to leave the bus in a hung state if
//  no call to endTransmission(true) is made. Some I2C
//  devices will behave oddly if they do not see a STOP.
//
uint8_t TwoWire::endTransmission(uint8_t sendStop)
{
  // transmit buffer (blocking)
  int8_t ret = twi_writeTo(txAddress, txBuffer, txBufferLength, 1, sendStop);
  // reset tx buffer iterator vars
  txBufferIndex = 0;
  txBufferLength = 0;
  // indicate that we are done transmitting
  transmitting = 0;
  return ret;
}

//  This provides backwards compatibility with the original
//  definition, and expected behaviour, of endTransmission
//
uint8_t TwoWire::endTransmission(void)
{
  return endTransmission(true);
}

// must be called in:
// slave tx event callback
// or after beginTransmission(address)
size_t TwoWire::write(uint8_t data)
{
  if(transmitting){
  // in master transmitter mode
    // don't bother if buffer is full
    if(txBufferLength >= BUFFER_LENGTH){
      setWriteError();
      return 0;
    }
    // put byte in tx buffer
    txBuffer[txBufferIndex] = data;
    ++txBufferIndex;
    // update amount in buffer   
    txBufferLength = txBufferIndex;
  }else{
  // in slave send mode
    // reply to master
    twi_transmit(&data, 1);
  }
  return 1;
}

// must be called in:
// slave tx event callback
// or after beginTransmission(address)
size_t TwoWire::write(const uint8_t *data, size_t quantity)
{
  if(transmitting){
  // in master transmitter mode
    for(size_t i = 0; i < quantity; ++i){
      write(data[i]);
    }
  }else{
  // in slave send mode
    // reply to master
    twi_transmit(data, quantity);
  }
  return quantity;
}

// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::available(void)
{
  return rxBufferLength - rxBufferIndex;
}

// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::read(void)
{
  int value = -1;

  // get each successive byte on each call
  if(rxBufferIndex < rxBufferLength){
    value = rxBuffer[rxBufferIndex];
    ++rxBufferIndex;
  }

  return value;
}

// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::peek(void)
{
  int value = -1;

  if(rxBufferIndex < rxBufferLength){
    value = rxBuffer[rxBufferIndex];
  }

  return value;
}

void TwoWire::flush(void)
{
  // XXX: to be implemented.
}

// behind the scenes function that is called when data is received
void TwoWire::onReceiveService(uint8_t* inBytes, int numBytes)
{
  // don't bother if user hasn't registered a callback
  if(!user_onReceive){
    return;
  }
  // don't bother if rx buffer is in use by a master requestFrom() op
  // i know this drops data, but it allows for slight stupidity
  // meaning, they may not have read all the master requestFrom() data yet
  if(rxBufferIndex < rxBufferLength){
    return;
  }
  // copy twi rx buffer into local read buffer
  // this enables new reads to happen in parallel
  for(uint8_t i = 0; i < numBytes; ++i){
    rxBuffer[i] = inBytes[i];    
  }
  // set rx iterator vars
  rxBufferIndex = 0;
  rxBufferLength = numBytes;
  // alert user program
  user_onReceive(numBytes);
}

// behind the scenes function that is called when data is requested
void TwoWire::onRequestService(void)
{
  // don't bother if user hasn't registered a callback
  if(!user_onRequest){
    return;
  }
  // reset tx buffer iterator vars
  // !!! this will kill any pending pre-master sendTo() activity
  txBufferIndex = 0;
  txBufferLength = 0;
  // alert user program
  user_onRequest();
}

// sets function called on slave write
void TwoWire::onReceive( void (*function)(int) )
{
  user_onReceive = function;
}

// sets function called on slave read
void TwoWire::onRequest( void (*function)(void) )
{
  user_onRequest = function;
}

// Preinstantiate Objects //////////////////////////////////////////////////////

TwoWire Wire = TwoWire();

Answer 1

这对你来说可能有点晚了，但是...我也使用 Eclipse 来完成我所有的 Arduino 开发，并且我已经看到了这个错误。这是因为 Eclipse 针对您的项目代码运行其自己的 C++ 代码分析工具。 (除了 G++ 工具链之外。)Eclipse 有时会遇到困难，或者过于热衷于发现错误，即使 GNU 编译器可以很好地编译代码并生成库。

查看项目属性、C/C++ 常规部分和代码分析选项卡。在语法和语义列表中，最后一个检查称为“抽象类无法实例化”。取消选中此项即可禁用该检查。然后点击“应用”。

最后，右键单击您的项目，然后选择“运行 C/C++ Code Analysys”，这将清除错误 - 不再出现红色 X。

希望这有帮助。