hw4.c

pthread_mutex_t buffer_mutex = PTHREAD_MUTEX_INITIALIZER;     
pthread_cond_t buffer_full = PTHREAD_COND_INITIALIZER;      
pthread_cond_t buffer_empty = PTHREAD_COND_INITIALIZER;
int buffer[10];

void buffer_init(void)
{
/*  printf("buffer_init called: buffer initialized with ten 0s\n"); */
  int i = 0;
  for(i=0; i<10; i++) buffer[i] = 0;
}
void buffer_insert(int number)
{
  int i = 0;
  pthread_mutex_lock( &buffer_mutex );
  while (i < 10 && buffer[i] != 0){
    i++;
  }
  if (i == 10){
  /*  printf("buffer_insert called with %d: it's full, waiting \n", number); */
    pthread_cond_wait( &buffer_full, &buffer_mutex);
    i = 0;
    while (i < 10 && buffer[i] != 0){
      i++;
    }
  }

  buffer[i] = number;
  pthread_cond_signal( &buffer_empty );
/*  printf("buffer_insert called with %d: inserted into %d \n", number, i); */
  pthread_mutex_unlock ( &buffer_mutex );
  
}

int buffer_extract(void)
{
  int i = 0;
  int return_val = 0;
  pthread_mutex_lock( &buffer_mutex );
  while (i < 10 && buffer[i] == 0){
    i++;
  }
  if (i == 10){
  /*  printf("buffer_remove called: it's empty, waiting \n"); */
    pthread_cond_wait( &buffer_empty, &buffer_mutex);
    i = 0;
    while (i < 10 && buffer[i] == 0){
      i++;
    }
  }

  return_val = buffer[i];
  buffer[i] = 0;
  pthread_cond_signal( &buffer_full );
 /* printf("buffer_extract called: returning %d\n", return_val); */
  pthread_mutex_unlock ( &buffer_mutex );
  return(return_val);                
   
}