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

HANDLE hMapFile;
LPVOID lpMapAddress;

HANDLE hEventAccess;
LPCSTR fEventProd="Access";		


/************************************************************************
 * void ErrorOut(LPSTR errstring)
 *
 * Purpose: Print out an meainful error code by means of
 *        GetLastError and printf
 *
 * Inputs:  errstring - the action that failed, passed by the
 *                    calling proc.
 *
 * Returns: none
 *
 * Calls:   GetLastError
 *
\************************************************************************/
void ErrorOut(LPSTR errstring)
{
   MessageBox(NULL, errstring, NULL, MB_OK);
}



/**************************************************************************
 * HANDLE CreateMap(HANDLE FileToBeMapped, char *MapName )
 *
 * Purpose: Create File Mapping object using the open file handle
 *
 * Inputs:  FileToBeMapped - handle to the file
 *
 * Returns: MapHandle - handle to the file mapping object
 *                    or NULL if failure
 *
 * Calls:   CreateFileMapping, ErrorOut
\**************************************************************************/
HANDLE CreateMap(HANDLE FileToBeMapped, LPSTR MapName)
{
   HANDLE MapHandle;

   MapHandle= CreateFileMapping(FileToBeMapped,
                                NULL,
                                PAGE_READWRITE,
                                0,
                                4096,
                                MapName);

   if (MapHandle == NULL)
   {
      ErrorOut("CreateFileMapping");
      return(NULL);
   }
   else
      return(MapHandle);
}


/**************************************************************************
 * LPVOID MapView(HANDLE hMap)
 *
 * Purpose: Map the file mapping object into address space
 *
 * Inputs:  hMap - handle to the mapping object
 *
 * Returns: MappedPointer - pointer to the address space that the
 *                        object is mapped into
 *                        or NULL if failure
 *
 * Calls:   MapViewOfFile, ErrorOut
 *
\**************************************************************************/
LPVOID MapView(HANDLE hMap)
{
   LPVOID MappedPointer;

   MappedPointer= MapViewOfFile(hMap,
                                FILE_MAP_WRITE | FILE_MAP_READ,
                                0, 0, 4096);
   if (MappedPointer == NULL)
   {
      ErrorOut("MapViewOfFile");
      return(NULL);
   }
   else
      return(MappedPointer);
}



LPVOID ReadBytes(LPVOID from, LPVOID to, DWORD len)
{
	return(memcpy(to,from,len));
}


LPVOID WriteBytes(LPVOID to, LPVOID from, DWORD len)
{
	return(memcpy(to,from,len));
}




int main()
{
	MessageBox(NULL,"Consumer started","Consumer",MB_OK);

	hEventAccess=CreateEvent(NULL,FALSE,FALSE,"Access");

	hMapFile = CreateMap((HANDLE) 0xFFFFFFFF, "Warehouse");
	lpMapAddress = MapView(hMapFile);


	int crt_items;
	

	for(;;)
	{
		Sleep(rand()/100);
		WaitForSingleObject(hEventAccess, INFINITE);
		ReadBytes(lpMapAddress, &crt_items, sizeof(int));
		if (crt_items>0)
		{
			crt_items--;
			WriteBytes(lpMapAddress, &crt_items, sizeof(int));
			printf("Consumed 1 item\n");
		}
		else
			printf("No items in stock\n");
		SetEvent(hEventAccess);
	}
	
	//cleanup
	UnmapViewOfFile(lpMapAddress);
	CloseHandle(hMapFile);
	
	return 0;
}