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FreeScan/SerialPort.cpp

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/*
** 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.
** NOTE: Writing is now not on thread *** ARW ***
**
** CREATION DATE 15-09-1997
** LAST MODIFICATION 05-04-2020
**
** AUTHOR Remon Spekreijse
** MODIFIED BY Brian Koh Sze Hsian - Andy Whittaker - Tom Herrmann
**
*/
// (c) 1996-99 Andy Whittaker, Chester, England.
// mail@andywhittaker.com
#include "SerialPort.h"
#include "EnumSer.h"
#include <assert.h>
#include <afxwin.h>
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
//Static members must be globally defined
CRITICAL_SECTION CSerialPort::m_csCommunicationSync;
OVERLAPPED CSerialPort::m_ov;
int CSerialPort::m_nActualWriteBufferSize = 0;
////////// Exception handling code
void AfxThrowSerialException(DWORD dwError /* = 0 */)
{
if (dwError == 0)
dwError = ::GetLastError();
CSerialException* pException = new CSerialException(dwError);
TRACE(_T("Warning: throwing CSerialException for error %d\n"), dwError);
THROW(pException);
}
BOOL CSerialException::GetErrorMessage(LPTSTR pstrError, UINT nMaxError, PUINT pnHelpContext)
{
ASSERT(pstrError != NULL && AfxIsValidString(pstrError, nMaxError));
if (pnHelpContext != NULL)
*pnHelpContext = 0;
LPTSTR lpBuffer;
BOOL bRet = FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
NULL, m_dwError, MAKELANGID(LANG_NEUTRAL, SUBLANG_SYS_DEFAULT),
(LPTSTR) &lpBuffer, 0, NULL);
if (bRet == FALSE)
*pstrError = '\0';
else
{
lstrcpyn(pstrError, lpBuffer, nMaxError);
bRet = TRUE;
LocalFree(lpBuffer);
}
return bRet;
}
CString CSerialException::GetErrorMessage()
{
CString rVal;
LPTSTR pstrError = rVal.GetBuffer(4096);
GetErrorMessage(pstrError, 4096, NULL);
rVal.ReleaseBuffer();
return rVal;
}
CSerialException::CSerialException(DWORD dwError)
{
m_dwError = dwError;
}
CSerialException::~CSerialException()
{
}
IMPLEMENT_DYNAMIC(CSerialException, CException)
#ifdef _DEBUG
void CSerialException::Dump(CDumpContext& dc) const
{
CObject::Dump(dc);
dc << "m_dwError = " << m_dwError;
}
#endif
//
// Constructor
CSerialPort::CSerialPort()
{
m_hComm = NULL;
m_Thread = NULL; // arw: fix for assertion without creating thread.
// initialize overlapped structure members to zero
m_ov.Offset = 0;
m_ov.OffsetHigh = 0;
// create events
m_ov.hEvent = NULL;
m_hShutdownEvent = NULL;
m_bThreadAlive = FALSE;
m_szWriteBuffer = NULL;
m_nWriteBufferSize = 0;
// Recall previous settings from the registry, default Com 1 in case 1st time run.
CWinApp* pApp = AfxGetApp();
m_nPortNr = pApp->GetProfileInt(_T("Communications"), _T("Port"), 1);
m_nWriteDelay = pApp->GetProfileInt(_T("Communications"), _T("WriteDelay"), 100);
m_timeLastWrittenToPort = { 0 };
m_bInitDone = FALSE;
}
// Delete dynamic memory
CSerialPort::~CSerialPort()
{
// Save our settings to the registry
CWinApp* pApp = AfxGetApp();
pApp->WriteProfileInt(_T("Communications"), _T("Port"), m_nPortNr);
pApp->WriteProfileInt(_T("Communications"), _T("WriteDelay"), m_nWriteDelay);
// resume the thread if it was suspended. Needed to process m_hShutdownEvent!
if(m_Thread != NULL)
{
DWORD dwSuspendCount;
do
{
dwSuspendCount = m_Thread->ResumeThread();
}
while ((dwSuspendCount != 0) && (dwSuspendCount != 0xffffffff));
do
{
SetEvent(m_hShutdownEvent);
} while (m_bThreadAlive);
TRACE(_T("Thread ended\n"));
}
// close handles to avoid memory leaks
CloseHandle(m_ov.hEvent);
CloseHandle(m_hComm);
CloseHandle(m_hShutdownEvent);
m_hComm = NULL;
m_ov.hEvent = NULL;
m_hShutdownEvent = NULL;
if (m_szWriteBuffer != NULL)
delete[] m_szWriteBuffer;
DeleteCriticalSection(&m_csCommunicationSync);
}
IMPLEMENT_DYNAMIC(CSerialPort, CObject)
#ifdef _DEBUG
void CSerialPort::Dump(CDumpContext& dc) const
{
CObject::Dump(dc);
dc << _T("m_hComm = ") << m_hComm << _T("\n");
}
#endif
//
// Initialize the port. This can be any Com Port.
BOOL CSerialPort::InitPort(CWnd* pPortOwner, // the owner (CWnd) of the port (receives message)
UINT portnr, // portnumber (e.g. 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 < 15);
if (portnr == NULL)
{// Use the last port setting.
TRACE(_T("CSerialPort::InitPort - Setting COM Port to last value\n"));
CWinApp* pApp = AfxGetApp();
m_nPortNr = pApp->GetProfileInt(_T("Communications"), _T("Port"), 1);
}
else
m_nPortNr = portnr;
// Call the 2nd override function
return InitPort(pPortOwner, baud, parity, databits, stopbits, dwCommEvents, writebuffersize);
}
// 2nd over-ride - uses the previous Com port number
BOOL CSerialPort::InitPort(CWnd* pPortOwner, // the owner (CWnd) of the port (receives message)
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
{
m_bInitDone = FALSE;
ASSERT(pPortOwner != NULL);
CWinApp* pApp = AfxGetApp();
m_nPortNr = pApp->GetProfileInt(_T("Communications"), _T("Port"), 1);
TRACE(_T("CSerialPort::InitPort - Com Port %d\n"), m_nPortNr);
if (m_nPortNr < 1)
{// This should never happen, however a mistake could have been made in the registry.
TRACE(_T("CSerialPort::InitPort - Com Port cannot be 0\n"));
return FALSE;
}
if (m_nPortNr > 255)
{// This should never happen, however a mistake could have been made in the registry.
TRACE(_T("CSerialPort::InitPort - Com Port cannot be greater than 255\n"));
return FALSE;
}
CEnumerateSerial::CPortsArray m_cuPorts;
CEnumerateSerial::UsingCreateFile(m_cuPorts);
if (m_cuPorts.size() == 0) {
TRACE(_T("CSerialPort::InitPort - No Com Ports found\n"));
return FALSE;
}
else {
BOOL foundPort = FALSE;
for (UINT i = 0; i < m_cuPorts.size(); ++i) {
if (m_nPortNr == m_cuPorts[i]) {
foundPort = TRUE;
break;
}
}
if (foundPort == FALSE) {
TRACE(_T("CSerialPort::InitPort - Selected Com Port not found\n"));
return FALSE;
}
}
// if the thread is alive: Kill
if (m_bThreadAlive)
{
do
{
SetEvent(m_hShutdownEvent);
} while (m_bThreadAlive);
TRACE(_T("Thread ended\n"));
}
// create events
if (m_ov.hEvent != NULL)
ResetEvent(m_ov.hEvent);
m_ov.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
if (!m_ov.hEvent)
AfxThrowSerialException();
if (m_hShutdownEvent != NULL)
ResetEvent(m_hShutdownEvent);
m_hShutdownEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
if (!m_hShutdownEvent)
AfxThrowSerialException();
// initialize the event objects
m_hEventArray[0] = m_hShutdownEvent; // highest priority
m_hEventArray[1] = m_ov.hEvent;
// initialize critical section
InitializeCriticalSection(&m_csCommunicationSync);
// set buffersize for writing and save the owner
m_pOwner = pPortOwner;
m_nWriteBufferSize = min(writebuffersize, MAX_WRITE_BUFFER);
if (m_szWriteBuffer != NULL) // delete the buffer if it exists
delete [] m_szWriteBuffer;
m_szWriteBuffer = new unsigned char[m_nWriteBufferSize + 1];
memset(m_szWriteBuffer, 0, m_nWriteBufferSize + 1);
m_dwCommEvents = dwCommEvents;
char *szPort = new char[50];
char *szBaud = new char[50];
// now it's 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_s(szPort, 50, _T("COM%d"), m_nPortNr);
sprintf_s(szBaud, 50, _T("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;
TRACE(_T("Failed to open up the comms port\n"));
AfxThrowSerialException();
return FALSE;
}
// set the timeout values
m_CommTimeouts.ReadIntervalTimeout = 0;
m_CommTimeouts.ReadTotalTimeoutMultiplier = 0;
m_CommTimeouts.ReadTotalTimeoutConstant = 0;
m_CommTimeouts.WriteTotalTimeoutMultiplier = 0;
m_CommTimeouts.WriteTotalTimeoutConstant = 0;
// configure
if (SetCommTimeouts(m_hComm, &m_CommTimeouts))
{
if (SetCommMask(m_hComm, dwCommEvents))
{
if (GetCommState(m_hComm, &m_dcb))
{ // DCB Structure
m_dcb.fRtsControl = RTS_CONTROL_DISABLE; // disable RTS
m_dcb.fOutxCtsFlow = FALSE; // disable CTS
m_dcb.fOutxDsrFlow = FALSE; // disable DSR
m_dcb.fDtrControl = DTR_CONTROL_DISABLE; // disable DTR
m_dcb.fDsrSensitivity = FALSE; // Ignores DSR
m_dcb.fNull = FALSE; // Disable Null Stripping
m_dcb.fTXContinueOnXoff = FALSE; // disable XON/XOFF
m_dcb.fBinary = TRUE; // This is always TRUE in WIN32
m_dcb.fOutX = FALSE; // Disable XOFF checking
m_dcb.fInX = FALSE; // Disable XOFF generation
m_dcb.DCBlength = sizeof(DCB);
if (BuildCommDCB(szBaud, &m_dcb))
{
if (SetCommState(m_hComm, &m_dcb))
; // normal operation... continue
else
ProcessErrorMessage(_T("SetCommState()"));
}
else
ProcessErrorMessage(_T("BuildCommDCB()"));
}
else
ProcessErrorMessage(_T("GetCommState()"));
}
else
ProcessErrorMessage(_T("SetCommMask()"));
}
else
ProcessErrorMessage(_T("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);
EscapeCommFunction(m_hComm, SETDTR); // This is needed for self-powered interfaces
EscapeCommFunction(m_hComm, SETRTS); // This is needed for self-powered interfaces
TRACE(_T("Initialisation for Com Port %d completed.\n"),
m_nPortNr);
ftime(&m_timeLastWrittenToPort); // init this to senseble value
m_bInitDone = TRUE;
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;
TRACE(_T("Com Port %d thread is starting.\n"), port->m_nPortNr);
// Set the status variable in the dialog class to
// TRUE to indicate the thread is running.
port->m_bThreadAlive = TRUE;
// Misc. variables
DWORD Event = 0;
DWORD CommEvent = 0;
DWORD dwError = 0;
COMSTAT comstat = { 0 };
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-signaled state if there are no bytes
// available to be read, or to a signaled state if there are bytes available.
// If this event handle is set to the non-signaled state, it will be set to
// signaled 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
// occurred. Process this error.
port->ProcessErrorMessage("WaitCommEvent()");
AfxThrowSerialException();
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-signaled 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() occurs, it will
// read all of the bytes from the buffer, and the program will
// loop back around to WaitCommEvent().
//
// At this point you will be in the situation where m_OverlappedStruct.hEvent is set,
// but there are no bytes available to read. If you proceed and call
// ReadFile(), it will return immediatly due to the async port setup, but
// GetOverlappedResults() will not return until the next character arrives.
//
// It is not desirable for the GetOverlappedResults() function to be in
// this state. The thread shutdown event (event 0) will not work if the
// thread is blocked by GetOverlappedResults().
//
// The solution to this is to check the buffer with a call to ClearCommError().
// This call will reset the event handle, and if there are no bytes to read
// we can loop back through WaitCommEvent() again, then proceed.
// If there are really bytes to read, do nothing and proceed.
bResult = ClearCommError(port->m_hComm, &dwError, &comstat);
if (!bResult)
AfxThrowSerialException();
if (comstat.cbInQue == 0)
continue;
} // end if bResult
// Main wait function. This function will normally block the thread
// until one of nine events occur that require action.
Event = WaitForMultipleObjects(2, port->m_hEventArray, FALSE, INFINITE);
Event = Event - WAIT_OBJECT_0; // WaitForMultipleObjects help says to do this.
switch (Event)
{
case 0:
{
// Shutdown event. This is event zero so it will be
// the highest priority and be serviced first.
// Tell the rest of the code that the thread is dying.
port->m_bThreadAlive = FALSE;
break;
} // case 0
case 1: // read event
{
bResult = GetCommMask(port->m_hComm, &CommEvent);
if (!bResult)
AfxThrowSerialException();
// if (CommEvent & EV_CTS)
// ::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_CTS_DETECTED,
// (WPARAM) 0, (LPARAM) port->m_nPortNr);
// if (CommEvent & EV_RXFLAG)
// ::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_RXFLAG_DETECTED,
// (WPARAM) 0, (LPARAM) port->m_nPortNr);
// if (CommEvent & EV_BREAK)
// ::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_BREAK_DETECTED,
// (WPARAM) 0, (LPARAM) port->m_nPortNr);
// if (CommEvent & EV_ERR)
// ::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_ERR_DETECTED,
// (WPARAM) 0, (LPARAM) port->m_nPortNr);
// if (CommEvent & EV_RING)
// ::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_RING_DETECTED,
// (WPARAM) 0, (LPARAM) port->m_nPortNr);
if (CommEvent & EV_RXCHAR)
// Receive character event from port.
ReceiveChar(port, comstat);
break;
} // case 1
} // end switch
// we're exiting, break out of loop and end thread
if (port->m_bThreadAlive == FALSE)
break;
} // close forever loop
// when we get here, the thread is about to shutdown and exit.
TRACE(_T("Com Port %d thread about to die.\n"), port->m_nPortNr);
return 0;
}
// Start comm watching
BOOL CSerialPort::StartMonitoring()
{
if (m_bInitDone == false) {
TRACE(_T("Com Port %d cannot be started. Init did not complete.\n"), m_nPortNr);
return FALSE;
}
TRACE(_T("Com Port %d starting monitoring.\n"), m_nPortNr);
m_Thread = AfxBeginThread(CommThread, this, THREAD_PRIORITY_NORMAL);
if (m_Thread == NULL) {
return FALSE;
}
// Clear buffer
PurgeComm(m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
TRACE(_T("Thread %ld started\n"), (DWORD)m_Thread->m_nThreadID);
return TRUE;
}
// Restart the comm thread
BOOL CSerialPort::RestartMonitoring()
{
if (m_bInitDone == false) {
TRACE(_T("Com Port %d cannot be restarted. Init did not complete.\n"), m_nPortNr);
return FALSE;
}
TRACE(_T("Com Port %d re-starting monitoring.\n"), m_nPortNr);
// Clear buffer
PurgeComm(m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
if(m_Thread != NULL)
m_Thread->ResumeThread();
else
StartMonitoring();
return TRUE;
}
// Suspend the comm thread
BOOL CSerialPort::StopMonitoring()
{
if(m_Thread != NULL)
{
TRACE(_T("Com Port %d stopped monitoring.\n"), m_nPortNr);
m_Thread->SuspendThread();
}
// Clear buffer
PurgeComm(m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
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_s(Temp, 200, _T("WARNING: %s Failed with the following error: \n%s\nPort: %d\n"),
(char*)ErrorText, (char*)lpMsgBuf, m_nPortNr);
MessageBox(NULL, Temp, _T("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;
// Gain ownership of the critical section
EnterCriticalSection(&port->m_csCommunicationSync);
if (bWrite)
{
// Initialise variables
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 COM Port
port->m_szWriteBuffer, // Pointer to message buffer in calling function
port->m_nActualWriteBufferSize,
&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:
{
// all other error codes
port->ProcessErrorMessage(_T("WriteFile()"));
AfxThrowSerialException();
}
}
}
else
{
LeaveCriticalSection(&port->m_csCommunicationSync);
}
} // end if(bWrite)
// If we have not written all the bytes out, we call GetOverlappedResult(..) to
// wait for the pending writes to happen.
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);
// deal with the error code
if (!bResult)
{
port->ProcessErrorMessage(_T("GetOverlappedResults() in WriteFile()"));
AfxThrowSerialException();
}
} // end if (!bWrite)
// Verify that the data size sent equals what we tried to send
if (BytesSent != (DWORD)port->m_nActualWriteBufferSize)
{
TRACE(_T("WARNING: WriteFile() error.. Bytes Sent: %d; Message Length: %d\n"),
BytesSent, port->m_nActualWriteBufferSize);
}
}
// Character received. Inform the owner
void CSerialPort::ReceiveChar(CSerialPort* port, COMSTAT comstat)
{
BOOL bRead = TRUE;
BOOL bResult = TRUE;
DWORD dwError = 0;
DWORD BytesRead = 0;
DWORD BytesToRead = 1; //modified
unsigned char RXBuff[MAXBYTESTOREAD];//modified
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);
BytesToRead = min(MAXBYTESTOREAD, comstat.cbInQue);
LeaveCriticalSection(&port->m_csCommunicationSync);
if (!bResult)
AfxThrowSerialException();
// 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
// solution 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
BytesToRead, // byte to read depends on que
&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()");
AfxThrowSerialException();
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(_T("GetOverlappedResults() in ReadFile()"));
AfxThrowSerialException();
}
} // 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) BytesRead);
} // end forever loop
}
// *************************************************************************************************
// Public Functions
//
// Write a string to the port - This can write even NULL characters
void CSerialPort::WriteToPort(unsigned char* string, int stringlength, BOOL bDelay)
{
DWORD messageLength = max(stringlength, 0);
DWORD halfDelay = max(5, m_nWriteDelay / 2);
assert(m_hComm != 0);
if (messageLength > m_nWriteBufferSize) {
messageLength = m_nWriteBufferSize;
}
::EnterCriticalSection(&m_csCommunicationSync);
memcpy(m_szWriteBuffer, string, messageLength);
if (messageLength < m_nWriteBufferSize) {
memset(m_szWriteBuffer + messageLength, 0, m_nWriteBufferSize - messageLength);
}
m_nActualWriteBufferSize=messageLength;
::LeaveCriticalSection(&m_csCommunicationSync);
if (bDelay) { // sleep to reduce stress on ECU serial port.
struct timeb currentTime = { 0 };
ftime(&currentTime);
time_t timeSinceLastWrite = ((currentTime.time - m_timeLastWrittenToPort.time) * 1000) + (currentTime.millitm - m_timeLastWrittenToPort.millitm);
if (timeSinceLastWrite < 0) {
// overflow...
Sleep(halfDelay);
}
else if (timeSinceLastWrite < halfDelay) {
Sleep((DWORD) (halfDelay - timeSinceLastWrite));
}
}
WriteChar(this); // Write to port immediately
if (bDelay) { // sleep to reduce stress on ECU serial port.
Sleep(halfDelay);
}
ftime(&m_timeLastWrittenToPort);
}
// Returns the device control block
DCB CSerialPort::GetDCB()
{
return m_dcb;
}
// Returns the communication event masks
DWORD CSerialPort::GetCommEvents()
{
return m_dwCommEvents;
}
// Returns the output buffer size
DWORD CSerialPort::GetWriteBufferSize()
{
return m_nWriteBufferSize;
}
// Returns the current port number
UINT CSerialPort::GetPort(void)
{
return m_nPortNr;
}
// Sets the internal com port number
void CSerialPort::SetPort(UINT nPort)
{
CWinApp* pApp = AfxGetApp();
pApp->WriteProfileInt(_T("Communications"), _T("Port"), nPort);
TRACE(_T(_T("Comms port number changed\n")));
}
// Returns the minimum number of milliseconds the TX routine will wait before returning
DWORD CSerialPort::GetWriteDelay(void)
{
return m_nWriteDelay;
}
// Sets the minimum number of milliseconds the TX routine will wait before returning
void CSerialPort::SetWriteDelay(DWORD nDelay)
{
m_nWriteDelay = nDelay;
// Write this to the registry
CWinApp* pApp = AfxGetApp();
pApp->WriteProfileInt(_T("Communications"), _T("WriteDelay"), m_nWriteDelay);
TRACE(_T("Comms port write delay changed\n"));
}
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