有关SerialPort的串口关闭问题，高手指点

#include "stdafx.h"
#include "SerialPort.h"#include <assert.h>
//
// Constructor
//
CSerialPort::CSerialPort()
{
m_hComm = NULL; // initialize overlapped structure members to zero
m_ov.Offset = 0;
m_ov.OffsetHigh = 0; // create events
m_ov.hEvent = NULL;
m_hWriteEvent = NULL;
m_hShutdownEvent = NULL; m_szWriteBuffer = NULL;
m_nWriteSize=1; m_bThreadAlive = FALSE;
}//
// Delete dynamic memory
//
CSerialPort::~CSerialPort()
{
do
{
SetEvent(m_hShutdownEvent);
} while (m_bThreadAlive);
TRACE("Thread ended\n");
delete [] m_szWriteBuffer;
}//
// Initialize the port. This can be port 1 to 4.
//
BOOL CSerialPort::InitPort(CWnd* pPortOwner, // the owner (CWnd) of the port (receives message)
   UINT  portnr, // portnumber (1..4)
   UINT  baud, // baudrate
   char  parity, // parity
   UINT  databits, // databits
   UINT  stopbits, // stopbits
   DWORD dwCommEvents, // EV_RXCHAR, EV_CTS etc
   UINT  writebuffersize) // size to the writebuffer
{
assert(portnr > 0 && portnr < 5);
assert(pPortOwner != NULL);
// if the thread is alive: Kill
if (m_bThreadAlive)
{
do
{
SetEvent(m_hShutdownEvent);
} while (m_bThreadAlive);
TRACE("Thread ended\n");
} // create events
if (m_ov.hEvent != NULL)
ResetEvent(m_ov.hEvent);
m_ov.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL); if (m_hWriteEvent != NULL)
ResetEvent(m_hWriteEvent);
m_hWriteEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

if (m_hShutdownEvent != NULL)
ResetEvent(m_hShutdownEvent);
m_hShutdownEvent = CreateEvent(NULL, TRUE, FALSE, NULL); // initialize the event objects
m_hEventArray[0] = m_hShutdownEvent; // highest priority
m_hEventArray[1] = m_ov.hEvent;
m_hEventArray[2] = m_hWriteEvent; // initialize critical section
InitializeCriticalSection(&m_csCommunicationSync);

// set buffersize for writing and save the owner
m_pOwner = pPortOwner; if (m_szWriteBuffer != NULL)
delete [] m_szWriteBuffer;
m_szWriteBuffer=new unsigned char[writebuffersize]; m_nPortNr = portnr; m_nWriteBufferSize = writebuffersize;
m_dwCommEvents = dwCommEvents; BOOL bResult = FALSE;
char *szPort = new char[50];
char *szBaud = new char[50]; // now it critical!
EnterCriticalSection(&m_csCommunicationSync); // if the port is already opened: close it
if (m_hComm != NULL)
{
CloseHandle(m_hComm);
m_hComm = NULL;
} // prepare port strings
sprintf(szPort, "COM%d", portnr);
sprintf(szBaud, "baud=%d parity=%c data=%d stop=%d", baud, parity, databits, stopbits); // get a handle to the port
m_hComm = CreateFile(szPort, // communication port string (COMX)
     GENERIC_READ | GENERIC_WRITE, // read/write types
     0, // comm devices must be opened with exclusive access
     NULL, // no security attributes
     OPEN_EXISTING, // comm devices must use OPEN_EXISTING
     FILE_ATTRIBUTE_NORMAL|FILE_FLAG_OVERLAPPED, // Async I/O
     0); // template must be 0 for comm devices if (m_hComm == INVALID_HANDLE_VALUE)
{
// port not found
delete [] szPort;
delete [] szBaud; return FALSE;
} // set the timeout values
m_CommTimeouts.ReadIntervalTimeout = 1000;
m_CommTimeouts.ReadTotalTimeoutMultiplier = 1000;
m_CommTimeouts.ReadTotalTimeoutConstant = 1000;
m_CommTimeouts.WriteTotalTimeoutMultiplier = 1000;
m_CommTimeouts.WriteTotalTimeoutConstant = 1000;
// configure
if (SetCommTimeouts(m_hComm, &m_CommTimeouts))
{
if (SetCommMask(m_hComm, dwCommEvents))
{
if (GetCommState(m_hComm, &m_dcb))
{
m_dcb.EvtChar = 'q';
m_dcb.fRtsControl=RTS_CONTROL_TOGGLE;//RTS_CONTROL_DISABLE;//RTS_CONTROL_ENABLE;// set RTS bit high!
if (BuildCommDCB(szBaud, &m_dcb))
{
if (SetCommState(m_hComm, &m_dcb))
; // normal operation... continue
else
ProcessErrorMessage("SetCommState()");
}
else
ProcessErrorMessage("BuildCommDCB()");
}
else
ProcessErrorMessage("GetCommState()");
}
else
ProcessErrorMessage("SetCommMask()");
}
else
ProcessErrorMessage("SetCommTimeouts()"); delete [] szPort;
delete [] szBaud; // flush the port
PurgeComm(m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT); // release critical section
LeaveCriticalSection(&m_csCommunicationSync); TRACE("Initialisation for communicationport %d completed.\nUse Startmonitor to communicate.\n", portnr); return TRUE;
}//
//  The CommThread Function.
//
UINT CSerialPort::CommThread(LPVOID pParam)
{
CSerialPort *port = (CSerialPort*)pParam;
port->m_bThreadAlive = TRUE; DWORD BytesTransfered = 0;
DWORD Event = 0;
DWORD CommEvent = 0;
DWORD dwError = 0;
COMSTAT comstat;
BOOL  bResult = TRUE;

if (port->m_hComm) //初始化，清除发送接收缓冲区，清除发送、接收的重叠I/O操作
PurgeComm(port->m_hComm,PURGE_RXCLEAR|PURGE_TXCLEAR|PURGE_RXABORT|PURGE_TXABORT);
//开始循环等待操作
for (;;)
{
bResult=WaitCommEvent(port->m_hComm, &Event, &port->m_ov);
//无限等待设定的事件发生，数组Event根据需要定义了须响应的接收，发送，关闭端口事件和OVERLAPPED类型的hEvent事件
if (!bResult)
{
switch (dwError = GetLastError())
{
case ERROR_IO_PENDING: //I/O操作还没有完成，函数返回0
{
break;
}
case 87: //NT WILL RETURN
{
break;
}
default:
{
port->ProcessErrorMessage("WaitCommEvent()");
break;
}
}
}
else
{
bResult = ClearCommError(port->m_hComm, &dwError, &comstat);//清除通信发生的错误
if (comstat.cbInQue==0)
continue;
} // end if bResult
Event = WaitForMultipleObjects(3, port->m_hEventArray, FALSE, INFINITE);
switch (Event)
{
case 0:
{
CloseHandle(port->m_hComm);
port->m_hComm=NULL;
port->m_bThreadAlive = FALSE;
AfxEndThread(100);
break;
}
case 1: // read event
{
GetCommMask(port->m_hComm, &CommEvent);
if (CommEvent & EV_RXCHAR) //接受到一个字符并放入输入缓冲区
ReceiveChar(port, comstat);
if (CommEvent & EV_CTS) //CTS（清除发送）改变状态
::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_CTS_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
if (CommEvent & EV_BREAK) //检测到输入的终止
::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_BREAK_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
if (CommEvent & EV_ERR) //发生了线路状态错误
::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_ERR_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
if (CommEvent & EV_RING) //检测到振铃
::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_RING_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
if (CommEvent & EV_RXFLAG) //接收到事件字符（DCB结构的EvtChar成员），并放入输入缓冲区
::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_RXFLAG_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
break;
}
case 2: // write event
{
//              EscapeCommFunction(port->m_hComm,SETRTS);
WriteChar(port);
// GetCommMask(port->m_hComm, &CommEvent);
// if(CommEvent==EV_TXEMPTY)
// {
// EscapeCommFunction(port->m_hComm,CLRRTS);
// ::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_TXEMPTY_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
// }
break;
}
} // end switch
} // close forever loop
return 0;
}
// start comm watching
BOOL CSerialPort::StartMonitoring()
{
if (!(m_Thread = AfxBeginThread(CommThread, this)))
return FALSE;
TRACE("Thread started\n");
return TRUE;
}
//
// Restart the comm thread
BOOL CSerialPort::RestartMonitoring()
{
TRACE("Thread resumed\n");
m_Thread->ResumeThread();
return TRUE;
}
//
// Suspend the comm thread
BOOL CSerialPort::StopMonitoring()
{
TRACE("Thread suspended\n");
m_Thread->SuspendThread();
return TRUE;
}
//
// If there is a error, give the right message
void CSerialPort::ProcessErrorMessage(char* ErrorText)
{
char *Temp = new char[200];

LPVOID lpMsgBuf; FormatMessage(
FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
NULL,
GetLastError(),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
(LPTSTR) &lpMsgBuf,
0,
NULL
);
sprintf(Temp, "WARNING:  %s Failed with the following error: \n%s\nPort: COM%d\n", (char*)ErrorText, lpMsgBuf, m_nPortNr);
MessageBox(NULL, Temp, "Application Error", MB_ICONSTOP);
LocalFree(lpMsgBuf);
delete [] Temp;
}
//
// Write a character.
void CSerialPort::WriteChar(CSerialPort* port)
{
BOOL bWrite = TRUE;
BOOL bResult = TRUE;
DWORD BytesSent = 0;
ResetEvent(port->m_hWriteEvent);
// Gain ownership of the critical section
EnterCriticalSection(&port->m_csCommunicationSync); if (bWrite)
{
port->m_ov.Offset = 0;
port->m_ov.OffsetHigh = 0;
// Clear buffer
PurgeComm(port->m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
bResult = WriteFile(port->m_hComm, // Handle to COMM Port
port->m_szWriteBuffer, // Pointer to message buffer in calling finction
port->m_nWriteSize, // Length of message to send
&BytesSent, // Where to store the number of bytes sent
&port->m_ov); // Overlapped structure
// deal with any error codes
if (!bResult)
{
DWORD dwError = GetLastError();
switch (dwError)
{
case ERROR_IO_PENDING:
{
// continue to GetOverlappedResults()
BytesSent = 0;
bWrite = FALSE;
break;
}
default:
port->ProcessErrorMessage("WriteFile()");// all other error codes
}
}
else
LeaveCriticalSection(&port->m_csCommunicationSync);
}
if (!bWrite)
{
bWrite = TRUE;
bResult = GetOverlappedResult(port->m_hComm, // Handle to COMM port
  &port->m_ov, // Overlapped structure
  &BytesSent, // Stores number of bytes sent
  TRUE); // Wait flag
LeaveCriticalSection(&port->m_csCommunicationSync);
}
::SendMessage((port->m_pOwner)->m_hWnd, WM_COMM_TXEMPTY_DETECTED,0,(LPARAM) port->m_nPortNr);
}void CSerialPort::ReceiveChar(CSerialPort* port, COMSTAT comstat)
{
BOOL  bRead = TRUE;
BOOL  bResult = TRUE;
DWORD dwError = 0;
DWORD BytesRead = 0;
unsigned char RXBuff;
for (;;)
{
// Gain ownership of the comm port critical section.
// This process guarantees no other part of this program
// is using the port object.
EnterCriticalSection(&port->m_csCommunicationSync);
// ClearCommError() will update the COMSTAT structure and
// clear any other errors.
bResult = ClearCommError(port->m_hComm, &dwError, &comstat);
LeaveCriticalSection(&port->m_csCommunicationSync);
// start forever loop.  I use this type of loop because I
// do not know at runtime how many loops this will have to
// run. My solution is to start a forever loop and to
// break out of it when I have processed all of the
// data available.  Be careful with this approach and
// be sure your loop will exit.
// My reasons for this are not as clear in this sample
// as it is in my production code, but I have found this
// solutiion to be the most efficient way to do this.

if (comstat.cbInQue == 0)
{
// break out when all bytes have been read
break;
}

EnterCriticalSection(&port->m_csCommunicationSync); if (bRead)
{
bResult = ReadFile(port->m_hComm, // Handle to COMM port
   &RXBuff, // RX Buffer Pointer
   1, // Read one byte
   &BytesRead, // Stores number of bytes read
   &port->m_ov); // pointer to the m_ov structure
// deal with the error code
if (!bResult)
{
switch (dwError = GetLastError())
{
case ERROR_IO_PENDING:
{
// asynchronous i/o is still in progress
// Proceed on to GetOverlappedResults();
bRead = FALSE;
break;
}
default:
{
// Another error has occured.  Process this error.
port->ProcessErrorMessage("ReadFile()");
break;
}
}
}
else
{
// ReadFile() returned complete. It is not necessary to call GetOverlappedResults()
bRead = TRUE;
}
}  // close if (bRead) if (!bRead)
{
bRead = TRUE;
bResult = GetOverlappedResult(port->m_hComm, // Handle to COMM port
  &port->m_ov, // Overlapped structure
  &BytesRead, // Stores number of bytes read
  TRUE); // Wait flag // deal with the error code
if (!bResult)
{
port->ProcessErrorMessage("GetOverlappedResults() in ReadFile()");
}
}  // close if (!bRead)

LeaveCriticalSection(&port->m_csCommunicationSync); // notify parent that a byte was received
::SendMessage((port->m_pOwner)->m_hWnd, WM_COMM_RXCHAR, (WPARAM) RXBuff, (LPARAM) port->m_nPortNr);
} // end forever loop}
void CSerialPort::WriteToPort(unsigned char* string,int n)
{
assert(m_hComm != 0);
memset(m_szWriteBuffer, 0, sizeof(m_szWriteBuffer));
memcpy(m_szWriteBuffer,string,n);
m_nWriteSize=n;
SetEvent(m_hWriteEvent);
}void CSerialPort::WriteToPort(LPCTSTR string,int n)
{
assert(m_hComm != 0); memset(m_szWriteBuffer, 0, sizeof(m_szWriteBuffer));
memcpy(m_szWriteBuffer,string,n);
m_nWriteSize=n;
SetEvent(m_hWriteEvent);
}
DCB CSerialPort::GetDCB()
{
return m_dcb;
}
DWORD CSerialPort::GetCommEvents()
{
return m_dwCommEvents;
}
DWORD CSerialPort::GetWriteBufferSize()
{
return m_nWriteBufferSize;
}
void CSerialPort::ClosePort()
{
if (m_bThreadAlive)
{
do
{
SetEvent(m_hShutdownEvent);
} while (m_bThreadAlive);
TRACE("Thread ended\n");
}
if (m_hComm != NULL)
{
CloseHandle(m_hComm);
m_hComm = NULL;
}
}
加一句
if (m_bThreadAlive)
{
do
{
SetCommMask(m_hComm, NULL);//还不行就换SetEvent( m_ov.hEvent);
SetEvent(m_hShutdownEvent);
} while (m_bThreadAlive);
TRACE("Thread ended\n");
}

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有关SerialPort的串口关闭问题，高手指点

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