internal static bool ClearCommError(IntPtr hPort, ref CommErrorFlags flags, CommStat stat)
{
if (FullFramework)
{
return(Convert.ToBoolean(WinClearCommError(hPort, ref flags, stat)));
}
else
{
return(Convert.ToBoolean(CEClearCommError(hPort, ref flags, stat)));
}
}
/// <summary>
/// Runs solely on a separate thread waiting on events to come in
/// from the communication port (OS) and handles those events.
/// </summary>
/// <remarks>Assumption made that port is open.</remarks>
/// <exception cref="System.Exception">
/// Thrown when a communication port error or a
/// system exception occurs.
/// </exception>
/// Revision History
/// MM/DD/YY who Version Issue# Description
/// -------- --- ------- ------ ---------------------------------------
/// 08/01/05 bdm 7.13.00 N/A Created
/// 08/17/06 mrj 7.35.00 Removed unused events
/// 03/02/07 mrj 8.00.16 Changed when the FlagCharReceived event
/// is fired.
///
private void CommEventThread()
{
CommEventFlags eventFlags = new CommEventFlags();
byte[] readbuffer = new Byte[m_uintRxBufSz];
string strErrDesc;
int intErr;
try
{
//Specify the set of events to be monitored for the port.
PortAPI.SetCommMask(m_hPort, CommEventFlags.ALL);
//Let Open() know the tread has started
m_rxThreadStartedEvent.Set();
while (IsOpen)
{
//Wait for a Comm event to happen
if (false == PortAPI.WaitCommEvent(m_hPort, ref eventFlags))
{
//WaitCommEvent failed - find out why
intErr = Marshal.GetLastWin32Error();
if (intErr == (int)APIErrors.ERROR_IO_PENDING)
{
//IO pending so just wait and try again.
//Suspend thread to allow other threads to execute.
Thread.Sleep(0);
continue;
}
if (intErr == (int)APIErrors.ERROR_INVALID_HANDLE)
{
//Calling Communication.Close() causes m_hPort to
//become invalid.
//Since Thread.Abort() is unsupported in the CF,
//we must accept that calling Close will throw
//an error here.
//Close signals the m_ptrCloseEvent, so wait on it
//We wait 1 second, though Close should happen
//much sooner
int intEventResult = PortAPI.WaitForSingleObject(m_ptrCloseEvent, 1000);
if (intEventResult == (int)APIConstants.WAIT_OBJECT_0)
{
// the event was set so close was called
m_hPort = (IntPtr)PortAPI.INVALID_HANDLE_VALUE;
// reset our ResetEvent for the next call
//to Open()
m_rxThreadStartedEvent.Reset();
return;
}
}
//WaitCommEvent failed!
strErrDesc = m_rmStrings.GetString("WAIT_COMM_EVENT_FAILED");
strErrDesc = string.Format(strErrDesc, intErr);
throw (new Exception(strErrDesc));
}
//Re-specify the set of events to be monitored for the port.
PortAPI.SetCommMask(m_hPort, CommEventFlags.ALL);
//Check the event for errors
if (((uint)eventFlags & (uint)CommEventFlags.ERR) != 0)
{
CommErrorFlags errorFlags = new CommErrorFlags();
CommStat commStat = new CommStat();
//Get the error status
if (false == PortAPI.ClearCommError(m_hPort,
ref errorFlags,
commStat))
{
//ClearCommError failed!
intErr = Marshal.GetLastWin32Error();
strErrDesc = m_rmStrings.GetString("CLEAR_COMM_ERROR_FAILED");
strErrDesc = string.Format(strErrDesc, intErr);
throw (new Exception(strErrDesc));
}
if (((uint)errorFlags & (uint)CommErrorFlags.BREAK) != 0)
{
//BREAK can set an error, so make sure the BREAK bit
//is set an continue
eventFlags |= CommEventFlags.BREAK;
}
else
{
//We have an error. Build a meaningful string and throw
//an exception
StringBuilder strMsg = new StringBuilder("UART Error: ", 80);
if ((errorFlags & CommErrorFlags.FRAME) != 0)
{
strMsg = strMsg.Append("Framing,");
}
if ((errorFlags & CommErrorFlags.IOE) != 0)
{
strMsg = strMsg.Append("IO,");
}
if ((errorFlags & CommErrorFlags.OVERRUN) != 0)
{
strMsg = strMsg.Append("Overrun,");
}
if ((errorFlags & CommErrorFlags.RXOVER) != 0)
{
strMsg = strMsg.Append("Receive Overflow,");
}
if ((errorFlags & CommErrorFlags.RXPARITY) != 0)
{
strMsg = strMsg.Append("Parity,");
}
if ((errorFlags & CommErrorFlags.TXFULL) != 0)
{
strMsg = strMsg.Append("Transmit Overflow,");
}
//No known bits are set
if (strMsg.Length == 12)
{
strMsg = strMsg.Append("Unknown");
}
//Raise an error event to anyone listening
//if (null != OnError)
//OnError(strMsg.ToString());
continue;
}
} //End if( ( (uint)eventFlags & (uint)CommEventFlags.ERR ) != 0 )
//Check for status changes
//08-12-05 bdm: Frankly, not sure for what purpose status = 0.
// But hesitate to modify since the code was borrowed
// and there does not exist a client that catches
// these events.
//uint status = 0;
//Check for RXFLAG
if (((uint)eventFlags & (uint)CommEventFlags.RXFLAG) != 0)
{
//if (null != FlagCharReceived)
//FlagCharReceived();
}
//Check for RXCHAR
if ((eventFlags & CommEventFlags.RXCHAR) != 0)
{
//Let the client know that we have received a character
if (null != FlagCharReceived)
{
FlagCharReceived();
}
}
} // while(true)
} // try
catch (Exception e)
{
throw (e);
}
}
extern private static int WinClearCommError(IntPtr hFile, ref CommErrorFlags lpErrors, CommStat lpStat);
