VC++ 的串口通讯(6)

wsprintf( szPort, "COM%d", nPort );
m_hComDev = CreateFile( szPort, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, NULL );
if( m_hComDev == NULL ) return( FALSE );

memset( &m_OverlappedRead, 0, sizeof( OVERLAPPED ) );
memset( &m_OverlappedWrite, 0, sizeof( OVERLAPPED ) );

COMMTIMEOUTS CommTimeOuts;
CommTimeOuts.ReadIntervalTimeout = 0xFFFFFFFF;
CommTimeOuts.ReadTotalTimeoutMultiplier = 0;
CommTimeOuts.ReadTotalTimeoutConstant = 0;
CommTimeOuts.WriteTotalTimeoutMultiplier = 0;
CommTimeOuts.WriteTotalTimeoutConstant = 5000;
SetCommTimeouts( m_hComDev, &CommTimeOuts );

m_OverlappedRead.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
m_OverlappedWrite.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );

dcb.DCBlength = sizeof( DCB );
GetCommState( m_hComDev, &dcb );
dcb.BaudRate = nBaud;
dcb.ByteSize = 8;
if( !SetCommState( m_hComDev, &dcb ) ||
!SetupComm( m_hComDev, 10000, 10000 ) ||
m_OverlappedRead.hEvent == NULL ||
m_OverlappedWrite.hEvent == NULL ){
DWORD dwError = GetLastError();
if( m_OverlappedRead.hEvent != NULL ) CloseHandle( m_OverlappedRead.hEvent );
if( m_OverlappedWrite.hEvent != NULL ) CloseHandle( m_OverlappedWrite.hEvent );
CloseHandle( m_hComDev );
return FALSE;
}

m_bOpened = TRUE;

return m_bOpened;

}

int CSerial::InBufferCount( void )
{

if( !m_bOpened || m_hComDev == NULL ) return( 0 );

DWORD dwErrorFlags;
COMSTAT ComStat;

ClearCommError( m_hIDComDev, &dwErrorFlags, &ComStat );

return (int)ComStat.cbInQue;

}