// This Barrier can be used only once and cannot be reused.
// Header file sbarrier.h  for class Barrier. (SingleBarrier use)
// Includes all functions associated with the Barrier
// To use a Barrier, first share a pointer variable of size
// (Barrier*) and use Barrierinit function on that pointer
// passing the numtoblock.



// For example, if 3 processes are to be blocked,
//	Barrier *B;
//      B = (Barrier*)shareint(sizeof(Barrier*), shareid);
//      B->Barrierinit(3);


#ifndef BARRIER_H
#define BARRIER_H
#include <iostream>
using namespace std;

#include "utility.h"

class Barrier {
public:
	Barrier();				//default constructor
	~Barrier() {}				//destructor
      void Barrierinit(int numtoblock);      // initialize barrier
      void WaitAtBarrier();                   //Blocks processes
      void SemRelease();                      //Releases Semaphores

private:
	int toblock;
	int gateopen;
	int blocked;
	int gate;

};

Barrier::Barrier()
{
	toblock = blocked = gateopen = gate = 0;
}

void Barrier::Barrierinit(int numtoblock)
{
	toblock = numtoblock;		//Number of processes to block
	gateopen = 0;			//status of gate
	blocked = 0;			//No process have called yet
	spin_lock_init(gate, 0);	//Initialize spinlock controlling barrier
}



void Barrier::WaitAtBarrier()
{
	spin_lock(gate);
      blocked++;				// Increment number of processes at gate
	if (blocked == toblock)		// All processes at the gate
	{
	    gateopen = 1;			// Open the gate
	}
	spin_unlock(gate);

	while (!gateopen);		// Wait till gate opens

}


void Barrier::SemRelease()		// a public function to release semaphore
{
        clean_up_sem(gate);
}

#endif