c++ - WaitCommEvent 挂起

Question

我正在使用非重叠的 WaitCommEvent 来读取文件数据。我想提供一段代码如下...

SetCommMask (io_ptr->comPortHandles->hComPort, EV_RXCHAR|EV_TXEMPTY);
WaitCommEvent (io_ptr->comPortHandles->hComPort, &dwMask, 0);

if (dwMask &= EV_RXCHAR) {
  // Loop getting data.

  // Need to loop because our buffer is only 1024 bytes
  while (TRUE)
  {
    ClearCommError( io_ptr->comPortHandles->hComPort, &dwError, &comstat);

    if (!comstat.cbInQue) continue;
    else 
    {
      if(comstat.cbInQue > 0)
        ReceiveInterrupt(io_ptr, comstat);
    }
    // Loop around and check for more data
    // In case additional byte has arrived while reading.
  }
}

Answer 1

如果文件句柄未打开并带有重叠标志，WaitCommEvent 将阻塞。在您的情况下，它将等待直到收到一个字符或发送完最后一个字符。

关于 WaitCommEvent 的 MSDN:

If hFile was not opened with FILE_FLAG_OVERLAPPED, WaitCommEvent does not return until one of the specified events or an error occurs.