Native DLL for GPS communication

// GpsDll.cpp 
//

#include "GpsDll.h"
#include "windows.h"
#include <stdio.h>

#ifdef _DEBUG
#define new DEBUG_NEW
#endif

static HANDLE m_hComm;


__declspec( dllexport ) 
int HelloDll() // just for testing
{
	return 42;
}

__declspec( dllexport ) 
int InitGpsCom(int Port, int BaudRate, int ByteSize, int StopBits, int Parity)
{
    TCHAR szPort[8];     
	HANDLE hComm;
	DCB dcb;
    DWORD flag;  
    COMMTIMEOUTS CommTimeOuts;

	wsprintf(szPort,_T("COM%d:"),Port); 
	hComm = CreateFile( szPort, GENERIC_READ | GENERIC_WRITE, 0, 
        NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL );

    if ( INVALID_HANDLE_VALUE==hComm )
        return FALSE;

    GetCommState( hComm, &dcb );
    dcb.BaudRate = (DWORD)BaudRate;
    dcb.ByteSize = (BYTE)ByteSize;
    dcb.StopBits = (BYTE)StopBits;
    dcb.fParity=!(Parity ==  0);

    dcb.Parity =  (BYTE)Parity;
    if ( !SetCommState(hComm, &dcb  ) )

    {    
        CloseHandle( hComm ); 

		ASSERT( FALSE); 
        return FALSE;        
	} 

            
    flag = EV_RXCHAR;
    SetCommMask( hComm,  flag|EV_BREAK  );
	
    CommTimeOuts.ReadIntervalTimeout = 0xFFFFFFFF;
    CommTimeOuts.ReadTotalTimeoutMultiplier=  0 ;
    CommTimeOuts.ReadTotalTimeoutConstant = 0  ;
    CommTimeOuts.WriteTotalTimeoutMultiplier =  10;
    CommTimeOuts.WriteTotalTimeoutConstant = 0 ;
    if(SetCommTimeouts(  hComm, &CommTimeOuts ) ==  0)
    {
        return FALSE; 
    }
    m_hComm = hComm;
    return TRUE;
}

__declspec( dllexport ) 
int PhysicalReceive(char* pReceive) 
{ 
    DWORD dwError; 
    COMSTAT cs; 
    ULONG nByteRead=0; 
    
    int errorcode; 
	int nLen =0;
	BOOL bReadSuc;
	errorcode = ClearCommError( m_hComm, &dwError, &cs ); 
	bReadSuc= ReadFile(m_hComm, pReceive, 1, &nByteRead, NULL); // max 1 char in buffer !
	if ( bReadSuc &&nByteRead>0 )
	{
		nLen = (int) nByteRead;
		return nLen;
	}
    errorcode=GetLastError();
    return -1;
}

__declspec( dllexport ) 
char ReadNextChar()
{
	char OneChar[2];
	while (PhysicalReceive((char*)&OneChar)==-1) {Sleep(200);}

	return OneChar[0];
}
__declspec( dllexport ) 
int CloseGpsCom()
{
	CloseHandle( m_hComm ); 

	return 1;
}