// Semafor.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

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

int bag;
int read_count;

HANDLE hMapFile;
LPVOID lpMapAddress;

HANDLE Writing, Status;

HANDLE CreateMap(HANDLE FileToBeMapped, LPCWSTR MapName)
{
   HANDLE MapHandle;

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

   if (MapHandle == NULL)
   {
	   printf("error: CreateFileMapping!\n");
      return(NULL);
   }
   else
      return(MapHandle);
}

LPVOID MapView(HANDLE hMap)
{
   LPVOID MappedPointer;

   MappedPointer= MapViewOfFile(hMap,
                                FILE_MAP_WRITE | FILE_MAP_READ,
                                0, 0, 4096);
   if (MappedPointer == NULL)
   {
	   printf("error: MapViewOfFile!\n");
      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));
}

void writer()
{
		WaitForSingleObject(Writing, INFINITE);
		ReadBytes(lpMapAddress, &bag, sizeof(int));
		bag++;
		WriteBytes(lpMapAddress, &bag, sizeof(int));
		printf("am scris: %d\n", bag);
		ReleaseMutex(Writing);
//		Sleep(1000);
}

void reader()
{
	WaitForSingleObject(Status, INFINITE);

	ReadBytes((int *)lpMapAddress+1, &read_count, sizeof(int));
	read_count++;
	WriteBytes((int *)lpMapAddress+1, &read_count, sizeof(int));

	if (read_count == 1)
		WaitForSingleObject(Writing, INFINITE);

	ReadBytes(lpMapAddress, &bag, sizeof(int));
	printf("am citit: %d\n", bag);

	ReadBytes((int *)lpMapAddress + 1, &read_count, sizeof(int));
	read_count--;
	WriteBytes((int *)lpMapAddress + 1, &read_count, sizeof(int));

	if (!read_count)
		ReleaseMutex(Writing);

	ReleaseMutex(Status);
//	Sleep(500);
}

int _tmain(int argc, _TCHAR* argv[])
{
	bag = 1;
	read_count = 0;

	hMapFile = CreateMap((HANDLE) 0xFFFFFFFF, L"Warehouse");
	lpMapAddress = MapView(hMapFile);//zona de memorie 
	

	Writing = CreateMutex(NULL, TRUE, L"Writing");

	if(GetLastError() != ERROR_ALREADY_EXISTS)
	{
		WriteBytes(lpMapAddress, &bag, sizeof(int));
		ReleaseMutex(Writing);
	}

	Status = CreateMutex(NULL, TRUE, L"Status");

	if(GetLastError() != ERROR_ALREADY_EXISTS)
	{
		WriteBytes((int *)lpMapAddress + 1, &read_count, sizeof(int));
		ReleaseMutex(Status);
	}

	while (1)
	{
		writer ();
		reader ();
		writer ();
		reader ();

		Sleep (500);
	}

	return 0;
}