#pragma once

class CDLLModule
{
public:
	CDLLModule() : m_hDLL(NULL)
	{
	}
	virtual ~CDLLModule()	//destructor, free the library
	{
		Release();
	}
	//////////////////////////////////////////////////////////////////
	// See if dll been loaded, returning true dose not mean that all
	// functions of the dll is valid.
	BOOL IsLoaded(void) 
	{
		return m_hDLL != NULL;
	}

	VOID Release()
	{
		if( m_hDLL )
			::FreeLibrary( m_hDLL );

		m_hDLL = NULL;
	}

	/////////////////////////////////////////////////////////
	//	pure virtual, must implemented in derived class
	//	used macros to generate the implementation
	virtual BOOL Init( LPCTSTR szDll ) = 0;

protected:
	HMODULE m_hDLL;
};

//////////////////////////////////////////////////////////////////////
// macros to implement the Init function
#define DECLARE_DLL_FUNCTION(ret, cc, func, params) \
	ret	(cc *func)params;

#define BEGIN_DLL_INIT() \
	BOOL Init( LPCTSTR szDll ) \
	{ \
		if( m_hDLL ) \
			::FreeLibrary( m_hDLL ); \
		m_hDLL = ::LoadLibrary( szDll ); \
		BOOL	bOk = FALSE;

#define INIT_DLL_TWIN_FUNCTION(ret, cc, func, params, origin) \
		if( m_hDLL ) { \
			func = (ret (cc* )params) GetProcAddress( m_hDLL, origin ); \
		} else \
			func = NULL; \
		if( func ) \
			bOk = TRUE;

#define END_DLL_INIT() \
		return bOk; \
	} 

#define INIT_DLL_FUNCTION(ret, cc, func, params) \
	if( m_hDLL ) { \
			func = (ret (cc* )params)GetProcAddress( m_hDLL, #func ); \
		} else \
			func = NULL; \
		if( func ) \
			bOk = TRUE;