/************************************************************
  File:          gsemaphore.h
  Description:   A program that simulates a dependancy graph 
                 for a set of threads.
                 The declaration and functions for a general
                 semaphore.
                                                         
  Author:        Dana Vrajitoru                          
  Organization:  IUSB                                    
  Date:          November 24, 2004
**************************************************************/

#ifndef GSEMAPHORE_H
#define GSEMAPHORE_H

#include <pthread.h>

struct Gsemaphore {
  int value;
  pthread_mutex_t mutex;
};

// Assigns the value of the second parameter to the internal semaphore
// value and initializes the mutex.
void Init_sem(Gsemaphore &sem, int val);

// Waits until the value has become 0, then increments it. It's a
// blocking function.
void Test_and_inc(Gsemaphore &sem);

// Decreases the value of the semaphore without testing it.
void Dec(Gsemaphore &sem);

#endif