The secondary message loop used in COMM-DRV/Lib is Win32 specific. Improved integration with MFC can be accomplished by doing the following.

1. After opening the serial port, use CdrvSetTimeOutFunction() to setup a callback on all COMM-DRV/Lib callbacks.

//Forward definition of function to prevent undeclared identifier error
int TimeoutFunction(int Port);

//Set timeout function that will cause prompt aborting of functions
CdrvSetTimeoutFunction(m_Port,TimeoutFunction);

//Prevent COMM-DRV/Lib's PeekMessage loop from being called. It will be done in
//the TimeoutFunction() to be MFC compliant.
SetSpecialBehavior(m_Port,SB_DoNotCall2ndMsgLoop,CDRV_TRUE,0);

 

2. Setup the callback function to handle MFC message handling.

//****************************************************************************
//*=====TimeoutFunction()
//*When installed by CdrvSetTimeoutFunction(), this function will
//*be called periodically whenever any COMM-DRV/Lib function is
//*block (waiting for data or waiting to send data). This function
//*returns 0 if it wants to effect a timeout on the function that is
//*blocked or 1 to do nothing.
//*
//*A PeekMessage is added below to supercede the PeekMessage
//*loop built into COMM-DRV/Lib since this method below is what
//*Microsoft recommends for an MFC PeekMessage loop. Note that
//*the COMM-DRV/Lib PeekMessage loop should be disabled with
//*SetSpecialBehavior(m_Port,SB_DoNotCall2ndMsgLoop,
//*CDRV_TRUE,0).
//****************************************************************************
int TimeoutFunction(int Port)
{
CForcedAbortDlg *p = (CForcedAbortDlg *)CdrvGetContext(Port,0);

MSG msg;
::PeekMessage(&msg,NULL,0,0,PM_NOREMOVE);
if (!AfxGetThread()->PumpMessage())
    ::PostQuitMessage(0);

// let MFC do its idle processing
LONG lIdle = 0;
while (AfxGetApp()->OnIdle(lIdle++));

return(1);
}
//****************************************************************************