Demonstrate that monitors and

A semaphore can be implemented using the following monitor code:

    monitor semaphore  {
        int value = 0;
        condition c;
        semaphore_increment ()  {
            value++;
            c.signal ();
        }
        semaphore_decrement ()  {
            while (value == 0)
            c.wait ();
            value --;
        }
}

A monitor could be implemented using a semaphore in the following manner.Each condition variable is represented by a queue of threads waiting for the condition.Each thread has a semaphore associated with its queue entry.When a thread performs a wait operation,it creates a new semaphore (initialized to zero),appends the semaphore to the queue associated with the condition variable,and performs a blocking semaphore decrement operation on the newly created semaphore.When a thread performs a signal on a condition variable,the first process in the queue is awakened by performing an increment on the corresponding semaphore.