Cserial port

/* ** FILENAME CSerialPort.cpp ** ** PURPOSE This class can read, write and watch one serial port. ** It sends messages to its owner when something happends on the port ** The class creates a thread for reading and writing so the main ** program is not blocked. ** ** CREATION DATE 15-09-1997 ** LAST MODIFICATION 12-11-1997 ** ** AUTHOR Remon Spekreijse ** ** */ #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_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 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_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.fRtsControl = 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) { // Cast the void pointer passed to the thread back to // a pointer of CSerialPort class CSerialPort *port = (CSerialPort*)pParam; // Set the status variable in the dialog class to // TRUE to indicate the thread is running. port->m_bThreadAlive = TRUE; // Misc. variables DWORD BytesTransfered = 0; DWORD Event = 0; DWORD CommEvent = 0; DWORD dwError = 0; COMSTAT comstat; BOOL bResult = TRUE; // Clear comm buffers at startup if (port->m_hComm) // check if the port is opened PurgeComm(port->m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT); // begin forever loop. This loop will run as long as the thread is alive. for (;;) { // Make a call to WaitCommEvent(). This call will return immediatly // because our port was created as an async port (FILE_FLAG_OVERLAPPED // and an m_OverlappedStructerlapped structure specified). This call will cause the // m_OverlappedStructerlapped element m_OverlappedStruct.hEvent, which is part of the m_hEventArray to // be placed in a non-signeled state if there are no bytes available to be read, // or to a signeled state if there are bytes available. If this event handle // is set to the non-signeled state, it will be set to signeled when a // character arrives at the port. // we do this for each port! bResult = WaitCommEvent(port->m_hComm, &Event, &port->m_ov); if (!bResult) { // If WaitCommEvent() returns FALSE, process the last error to determin // the reason.. switch (dwError = GetLastError()) { case ERROR_IO_PENDING: { // This is a normal return value if there are no bytes // to read at the port. // Do nothing and continue break; } case 87: { // Under Windows NT, this value is returned for some reason. // I have not investigated why, but it is also a valid reply // Also do nothing and continue. break; } default: { // All other error codes indicate a serious error has // occured. Process this error. port->ProcessErrorMessage("WaitCommEvent()"); break; } } } else { // If WaitCommEvent() returns TRUE, check to be sure there are // actually bytes in the buffer to read. // // If you are reading more than one byte at a time from the buffer // (which this program does not do) you will have the situation occur // where the first byte to arrive will cause the WaitForMultipleObjects() // function to stop waiting. The WaitForMultipleObjects() function // resets the event handle in m_OverlappedStruct.hEvent to the non-signelead state // as it returns. // // If in the time between the reset of this event and the call to // ReadFile() more bytes arrive, the m_OverlappedStruct.hEvent handle will be set again // to the signeled state. When the call to ReadFile()