/*
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** FILENAME CSerialPort.cpp
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**
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** PURPOSE This class can read, write and watch one serial port.
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** It sends messages to its owner when something happends on the port
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** The class creates a thread for reading and writing so the main
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** program is not blocked.
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**
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** CREATION DATE 15-09-1997
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** LAST MODIFICATION 12-11-1997
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**
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** AUTHOR Remon Spekreijse
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**
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**
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*/
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#include "stdafx.h"
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#include "CommThread.h"
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#include <assert.h>
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//
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// Constructor
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//
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CSerialPort::CSerialPort()
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{
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m_hComm = NULL;
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// initialize overlapped structure members to zero
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m_ov.Offset = 0;
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m_ov.OffsetHigh = 0;
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// create events
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m_ov.hEvent = NULL;
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m_hWriteEvent = NULL;
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m_hShutdownEvent = NULL;
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m_szWriteBuffer = NULL;
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m_bThreadAlive = FALSE;
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m_ReadComplete = FALSE;
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m_ReadCount = 0;
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}
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//
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// Delete dynamic memory
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//
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CSerialPort::~CSerialPort()
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{
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m_bThreadRun = FALSE;
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do
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{
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SetEvent(m_hShutdownEvent);
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} while (m_bThreadAlive);
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TRACE("Thread ended\n");
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delete [] m_szWriteBuffer;
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}
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//
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// Initialize the port. This can be port 1 to 4.
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//
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BOOL CSerialPort::InitPort(CWnd* pPortOwner, // the owner (CWnd) of the port (receives message)
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UINT portnr, // portnumber (1..4)
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UINT baud, // baudrate
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char parity, // parity
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UINT databits, // databits
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UINT stopbits, // stopbits
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DWORD dwCommEvents, // EV_RXCHAR, EV_CTS etc
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UINT writebuffersize) // size to the writebuffer
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{
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assert(portnr > 0 && portnr < 100);
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// assert(pPortOwner != NULL);
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// if the thread is alive: Kill
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if (m_bThreadAlive)
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{
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do
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{
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SetEvent(m_hShutdownEvent);
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} while (m_bThreadAlive);
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TRACE("Thread ended\n");
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}
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// create events
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if (m_ov.hEvent != NULL)
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ResetEvent(m_ov.hEvent);
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m_ov.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
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if (m_hWriteEvent != NULL)
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ResetEvent(m_hWriteEvent);
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m_hWriteEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
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if (m_hShutdownEvent != NULL)
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ResetEvent(m_hShutdownEvent);
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m_hShutdownEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
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// initialize the event objects
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m_hEventArray[0] = m_hShutdownEvent; // highest priority
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m_hEventArray[1] = m_ov.hEvent;
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m_hEventArray[2] = m_hWriteEvent;
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// initialize critical section
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InitializeCriticalSection(&m_csCommunicationSync);
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if (m_szWriteBuffer != NULL)
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delete [] m_szWriteBuffer;
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m_szWriteBuffer = new unsigned char[writebuffersize];
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m_nPortNr = portnr;
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m_nWriteBufferSize = writebuffersize;
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m_dwCommEvents = dwCommEvents;
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BOOL bResult = FALSE;
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char *szPort = new char[50];
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char *szBaud = new char[50];
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// now it critical!
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EnterCriticalSection(&m_csCommunicationSync);
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// if the port is already opened: close it
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if (m_hComm != NULL)
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{
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CloseHandle(m_hComm);
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m_hComm = NULL;
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}
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// prepare port strings
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sprintf(szPort, "COM%d", portnr);
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sprintf(szBaud, "baud=%d parity=%c data=%d stop=%d", baud, parity, databits, stopbits);
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// get a handle to the port
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m_hComm = CreateFile(szPort, // communication port string (COMX)
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GENERIC_READ | GENERIC_WRITE, // read/write types
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0, // comm devices must be opened with exclusive access
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NULL, // no security attributes
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OPEN_EXISTING, // comm devices must use OPEN_EXISTING
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FILE_FLAG_OVERLAPPED, // Async I/O
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0); // template must be 0 for comm devices
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if (m_hComm == INVALID_HANDLE_VALUE)
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{
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// port not found
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delete [] szPort;
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delete [] szBaud;
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return FALSE;
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}
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// set the timeout values
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m_CommTimeouts.ReadIntervalTimeout = 1000;
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m_CommTimeouts.ReadTotalTimeoutMultiplier = 1000;
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m_CommTimeouts.ReadTotalTimeoutConstant = 1000;
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m_CommTimeouts.WriteTotalTimeoutMultiplier = 1000;
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m_CommTimeouts.WriteTotalTimeoutConstant = 1000;
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// configure
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if (SetCommTimeouts(m_hComm, &m_CommTimeouts))
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{
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if (SetCommMask(m_hComm, dwCommEvents))
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{
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if (GetCommState(m_hComm, &m_dcb))
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{
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m_dcb.fRtsControl = RTS_CONTROL_ENABLE; // set RTS bit high!
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if (BuildCommDCB(szBaud, &m_dcb))
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{
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if (SetCommState(m_hComm, &m_dcb))
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; // normal operation... continue
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else
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ProcessErrorMessage("SetCommState()");
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}
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else
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ProcessErrorMessage("BuildCommDCB()");
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}
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else
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ProcessErrorMessage("GetCommState()");
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}
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else
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ProcessErrorMessage("SetCommMask()");
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}
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else
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ProcessErrorMessage("SetCommTimeouts()");
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delete [] szPort;
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delete [] szBaud;
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// flush the port
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PurgeComm(m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
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// release critical section
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LeaveCriticalSection(&m_csCommunicationSync);
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TRACE("Initialisation for communicationport %d completed.\nUse Startmonitor to communicate.\n", portnr);
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return TRUE;
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}
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//
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// The CommThread Function.
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//
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UINT CSerialPort::CommThread(LPVOID pParam)
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{
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// Cast the void pointer passed to the thread back to
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// a pointer of CSerialPort class
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CSerialPort *port = (CSerialPort*)pParam;
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// Set the status variable in the dialog class to
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// TRUE to indicate the thread is running.
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port->m_bThreadAlive = TRUE;
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// Misc. variables
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DWORD BytesTransfered = 0;
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DWORD Event = 0;
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DWORD CommEvent = 0;
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DWORD dwError = 0;
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COMSTAT comstat;
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BOOL bResult = TRUE;
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// Clear comm buffers at startup
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if (port->m_hComm) // check if the port is opened
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PurgeComm(port->m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
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// begin forever loop. This loop will run as long as the thread is alive.
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while (port->m_bThreadRun == TRUE)
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{
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// Make a call to WaitCommEvent(). This call will return immediatly
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// because our port was created as an async port (FILE_FLAG_OVERLAPPED
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// and an m_OverlappedStructerlapped structure specified). This call will cause the
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// m_OverlappedStructerlapped element m_OverlappedStruct.hEvent, which is part of the m_hEventArray to
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// be placed in a non-signeled state if there are no bytes available to be read,
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// or to a signeled state if there are bytes available. If this event handle
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// is set to the non-signeled state, it will be set to signeled when a
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// character arrives at the port.
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// we do this for each port!
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bResult = WaitCommEvent(port->m_hComm, &Event, &port->m_ov);
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if (!bResult)
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{
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// If WaitCommEvent() returns FALSE, process the last error to determin
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// the reason..
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switch (dwError = GetLastError())
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{
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case ERROR_IO_PENDING:
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{
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// This is a normal return value if there are no bytes
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// to read at the port.
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// Do nothing and continue
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break;
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}
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case 87:
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{
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// Under Windows NT, this value is returned for some reason.
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// I have not investigated why, but it is also a valid reply
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// Also do nothing and continue.
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break;
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}
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default:
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{
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// All other error codes indicate a serious error has
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// occured. Process this error.
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//port->ProcessErrorMessage("WaitCommEvent()");
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break;
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}
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}
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}
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else
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{
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// If WaitCommEvent() returns TRUE, check to be sure there are
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// actually bytes in the buffer to read.
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//
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// If you are reading more than one byte at a time from the buffer
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// (which this program does not do) you will have the situation occur
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// where the first byte to arrive will cause the WaitForMultipleObjects()
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// function to stop waiting. The WaitForMultipleObjects() function
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// resets the event handle in m_OverlappedStruct.hEvent to the non-signelead state
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// as it returns.
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//
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// If in the time between the reset of this event and the call to
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// ReadFile() more bytes arrive, the m_OverlappedStruct.hEvent handle will be set again
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// to the signeled state. When the call to ReadFile() occurs, it will
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// read all of the bytes from the buffer, and the program will
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// loop back around to WaitCommEvent().
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//
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// At this point you will be in the situation where m_OverlappedStruct.hEvent is set,
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// but there are no bytes available to read. If you proceed and call
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// ReadFile(), it will return immediatly due to the async port setup, but
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// GetOverlappedResults() will not return until the next character arrives.
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//
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// It is not desirable for the GetOverlappedResults() function to be in
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// this state. The thread shutdown event (event 0) and the WriteFile()
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// event (Event2) will not work if the thread is blocked by GetOverlappedResults().
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//
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// The solution to this is to check the buffer with a call to ClearCommError().
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// This call will reset the event handle, and if there are no bytes to read
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// we can loop back through WaitCommEvent() again, then proceed.
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// If there are really bytes to read, do nothing and proceed.
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bResult = ClearCommError(port->m_hComm, &dwError, &comstat);
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if (comstat.cbInQue == 0)
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continue;
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} // end if bResult
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// Main wait function. This function will normally block the thread
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// until one of nine events occur that require action.
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Event = WaitForMultipleObjects(3, port->m_hEventArray, FALSE, INFINITE);
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switch (Event)
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{
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case 0:
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{
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// Shutdown event. This is event zero so it will be
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// the higest priority and be serviced first.
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port->m_bThreadAlive = FALSE;
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// Kill this thread. break is not needed, but makes me feel better.
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AfxEndThread(100);
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break;
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}
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case 1: // read event
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{
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GetCommMask(port->m_hComm, &CommEvent);
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if (CommEvent & EV_RXCHAR)
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// Receive character event from port.
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ReceiveChar(port, comstat);
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break;
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}
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case 2: // write event
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{
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// Write character event from port
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WriteChar(port);
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break;
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}
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} // end switch
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} // close forever loop
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port->m_bThreadAlive = FALSE;
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return 0;
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}
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//
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// start comm watching
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//
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BOOL CSerialPort::StartMonitoring()
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{
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m_bThreadRun = TRUE;
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if (!(m_Thread = AfxBeginThread(CommThread, this)))
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return FALSE;
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TRACE("Thread started\n");
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return TRUE;
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}
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//
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// Restart the comm thread
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//
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BOOL CSerialPort::RestartMonitoring()
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{
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TRACE("Thread resumed\n");
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m_Thread->ResumeThread();
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return TRUE;
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}
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//
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// Suspend the comm thread
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//
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BOOL CSerialPort::StopMonitoring()
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{
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m_bThreadRun = FALSE;
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do
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{
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SetEvent(m_hShutdownEvent);
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} while (m_bThreadAlive);
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CloseHandle(m_hComm);
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return TRUE;
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}
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//
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// If there is a error, give the right message
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//
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void CSerialPort::ProcessErrorMessage(char* ErrorText)
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{
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char *Temp = new char[200];
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LPVOID lpMsgBuf;
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FormatMessage(
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FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
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NULL,
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GetLastError(),
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MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
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(LPTSTR) &lpMsgBuf,
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0,
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NULL
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);
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sprintf(Temp, "WARNING: %s Failed with the following error: \n%s\nPort: %d\n", (char*)ErrorText, lpMsgBuf, m_nPortNr);
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MessageBox(NULL, Temp, "Application Error", MB_ICONSTOP);
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LocalFree(lpMsgBuf);
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delete[] Temp;
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}
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//
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// Write a character.
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//
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void CSerialPort::WriteChar(CSerialPort* port)
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{
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BOOL bWrite = TRUE;
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BOOL bResult = TRUE;
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DWORD BytesSent = 0;
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ResetEvent(port->m_hWriteEvent);
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// Gain ownership of the critical section
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EnterCriticalSection(&port->m_csCommunicationSync);
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if (bWrite)
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{
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// Initailize variables
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port->m_ov.Offset = 0;
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port->m_ov.OffsetHigh = 0;
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// Clear buffer
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PurgeComm(port->m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
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bResult = WriteFile(port->m_hComm, // Handle to COMM Port
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port->m_szWriteBuffer, // Pointer to message buffer in calling finction
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port->m_WriteDataSize, // Length of message to send
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&BytesSent, // Where to store the number of bytes sent
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&port->m_ov); // Overlapped structure
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// deal with any error codes
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if (!bResult)
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{
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DWORD dwError = GetLastError();
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switch (dwError)
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{
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case ERROR_IO_PENDING:
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{
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// continue to GetOverlappedResults()
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BytesSent = 0;
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bWrite = FALSE;
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break;
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}
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default:
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{
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// all other error codes
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port->ProcessErrorMessage("WriteFile()");
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}
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}
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}
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else
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{
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LeaveCriticalSection(&port->m_csCommunicationSync);
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}
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} // end if(bWrite)
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if (!bWrite)
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{
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bWrite = TRUE;
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bResult = GetOverlappedResult(port->m_hComm, // Handle to COMM port
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&port->m_ov, // Overlapped structure
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&BytesSent, // Stores number of bytes sent
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TRUE); // Wait flag
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LeaveCriticalSection(&port->m_csCommunicationSync);
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// deal with the error code
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if (!bResult)
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{
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port->ProcessErrorMessage("GetOverlappedResults() in WriteFile()");
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}
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} // end if (!bWrite)
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// Verify that the data size send equals what we tried to send
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if (BytesSent != strlen((char*)port->m_szWriteBuffer))
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{
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TRACE("WARNING: WriteFile() error.. Bytes Sent: %d; Message Length: %d\n", BytesSent, strlen((char*)port->m_szWriteBuffer));
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}
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}
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//
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// Character received. Inform the owner
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//
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void CSerialPort::ReceiveChar(CSerialPort* port, COMSTAT comstat)
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{
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BOOL bRead = TRUE;
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BOOL bResult = TRUE;
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DWORD dwError = 0;
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DWORD BytesRead = 0;
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unsigned char RXBuff;
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for (;;)
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{
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// Gain ownership of the comm port critical section.
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// This process guarantees no other part of this program
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// is using the port object.
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EnterCriticalSection(&port->m_csCommunicationSync);
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// ClearCommError() will update the COMSTAT structure and
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// clear any other errors.
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bResult = ClearCommError(port->m_hComm, &dwError, &comstat);
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LeaveCriticalSection(&port->m_csCommunicationSync);
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// start forever loop. I use this type of loop because I
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// do not know at runtime how many loops this will have to
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// run. My solution is to start a forever loop and to
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// break out of it when I have processed all of the
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// data available. Be careful with this approach and
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// be sure your loop will exit.
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// My reasons for this are not as clear in this sample
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// as it is in my production code, but I have found this
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// solutiion to be the most efficient way to do this.
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if (comstat.cbInQue == 0)
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{
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// break out when all bytes have been read
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break;
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}
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EnterCriticalSection(&port->m_csCommunicationSync);
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if (bRead)
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{
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bResult = ReadFile(port->m_hComm, // Handle to COMM port
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&RXBuff, // RX Buffer Pointer
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1, // Read one byte
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&BytesRead, // Stores number of bytes read
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&port->m_ov); // pointer to the m_ov structure
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// deal with the error code
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if (!bResult)
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{
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switch (dwError = GetLastError())
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{
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case ERROR_IO_PENDING:
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{
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// asynchronous i/o is still in progress
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// Proceed on to GetOverlappedResults();
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bRead = FALSE;
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break;
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}
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default:
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{
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// Another error has occured. Process this error.
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port->ProcessErrorMessage("ReadFile()");
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break;
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}
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}
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}
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else
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{
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// ReadFile() returned complete. It is not necessary to call GetOverlappedResults()
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bRead = TRUE;
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}
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} // close if (bRead)
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if (!bRead)
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{
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bRead = TRUE;
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bResult = GetOverlappedResult(port->m_hComm, // Handle to COMM port
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&port->m_ov, // Overlapped structure
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&BytesRead, // Stores number of bytes read
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TRUE); // Wait flag
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// deal with the error code
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if (!bResult)
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{
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port->ProcessErrorMessage("GetOverlappedResults() in ReadFile()");
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}
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} // close if (!bRead)
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LeaveCriticalSection(&port->m_csCommunicationSync);
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// notify parent that a byte was received
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//::SendMessage((port->m_pOwner)->m_hWnd, WM_COMM_RXCHAR, (WPARAM) RXBuff, (LPARAM) port->m_nPortNr);
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port->m_ReadBuff[port->m_ReadCount++] = RXBuff;
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if (RXBuff == 0x0d)
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port->m_ReadComplete = TRUE;
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} // end forever loop
|
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}
|
|
//
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// Write a string to the port
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//
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void CSerialPort::WriteToPort(unsigned char* Data, UINT Size)
|
{
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assert(m_hComm != 0);
|
|
ClearReadBuff();
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memset(m_szWriteBuffer, 0, sizeof(m_szWriteBuffer));
|
memcpy(m_szWriteBuffer, Data, Size);
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m_WriteDataSize = Size;
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// set event for write
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SetEvent(m_hWriteEvent);
|
}
|
|
void CSerialPort::ClearReadBuff(void)
|
{
|
//memset(m_ReadBuff, 0, 256);
|
m_ReadComplete = FALSE;
|
m_ReadCount = 0;
|
}
|
|
//
|
// Return the device control block
|
//
|
DCB CSerialPort::GetDCB()
|
{
|
return m_dcb;
|
}
|
|
//
|
// Return the communication event masks
|
//
|
DWORD CSerialPort::GetCommEvents()
|
{
|
return m_dwCommEvents;
|
}
|
|
//
|
// Return the output buffer size
|
//
|
DWORD CSerialPort::GetWriteBufferSize()
|
{
|
return m_nWriteBufferSize;
|
}
|
