用C＃读取GPS数据的基类，适用于wince操作系统[4]

  );
  [DllImport("coredll.dll")]
  private static extern uint GetLastError();
  
  public void Open()
  {
  
   DCB dcbCommPort = new DCB();
   COMMTIMEOUTS ctoCommPort = new COMMTIMEOUTS(); 
    
   // 打开串口 OPEN THE COMM PORT.
   hComm = CreateFile(PortNum ,GENERIC_READ | GENERIC_WRITE,0, 0,OPEN_EXISTING,0,0);
   // 如果串口没有打开，就打开 IF THE PORT CANNOT BE OPENED, BAIL OUT.
   if(hComm == INVALID_HANDLE_VALUE)
   {
    throw(new ApplicationException("非法操作，不能打开串口！"));
   }
  
   // 设置通信超时时间 SET THE COMM TIMEOUTS.
   GetCommTimeouts(hComm,ref ctoCommPort);
   ctoCommPort.ReadTotalTimeoutConstant = ReadTimeout;
   ctoCommPort.ReadTotalTimeoutMultiplier = 0;
   ctoCommPort.WriteTotalTimeoutMultiplier = 0;
   ctoCommPort.WriteTotalTimeoutConstant = 0; 
   SetCommTimeouts(hComm,ref ctoCommPort);
  
   // 设置串口 SET BAUD RATE, PARITY, WORD SIZE, AND STOP BITS.
   GetCommState(hComm, ref dcbCommPort);
   dcbCommPort.BaudRate=BaudRate;
   dcbCommPort.flags=0;
   //dcb.fBinary=1;
   dcbCommPort.flags|=1;
   if (Parity>0)
   {
    //dcb.fParity=1
    dcbCommPort.flags|=2;
   }
   dcbCommPort.Parity=Parity;
   dcbCommPort.ByteSize=ByteSize;
   dcbCommPort.StopBits=StopBits;
   if (!SetCommState(hComm, ref dcbCommPort))
   {
    //uint ErrorNum=GetLastError();
    throw(new ApplicationException("非法操作，不能打开串口！"));
   }
   //unremark to see if setting took correctly
   //DCB dcbCommPort2 = new DCB();
   //GetCommState(hComm, ref dcbCommPort2);
   Opened = true;
  }
  
  public void Close()
  {
   if (hComm!=INVALID_HANDLE_VALUE)
   {
    CloseHandle(hComm);
   }
  }
  
  public byte[] Read(int NumBytes)
  {
   byte[] BufBytes;
   byte[] OutBytes;
   BufBytes = new byte[NumBytes];
   if (hComm!=INVALID_HANDLE_VALUE)
   {
    OVERLAPPED ovlCommPort = new OVERLAPPED();
    int BytesRead=0;
    ReadFile(hComm,BufBytes,NumBytes,ref BytesRead,ref ovlCommPort);
    try
    {
     OutBytes = new byte[BytesRead];
     Array.Copy(BufBytes,0,OutBytes,0,BytesRead);
    }
    catch
    {
     return BufBytes;
    }
    
   }
   else
   {
    throw(new ApplicationException("串口未打开！"));
   }
   return OutBytes;
   //   return BufBytes;
  }
  
  public void Write(byte[] WriteBytes)
  {
   if (hComm!=INVALID_HANDLE_VALUE)
   {
    OVERLAPPED ovlCommPort = new OVERLAPPED();
    int BytesWritten = 0;
    WriteFile(hComm,WriteBytes,WriteBytes.Length,ref BytesWritten,ref ovlCommPort);
   }
   else
   {
    throw(new ApplicationException("串口未打开！"));
   }  
  }