pthread_mutex_lock(&bstate.barrier_mutex);

  bstate.nthread++;
  if(bstate.nthread == nthread) {
    bstate.round++;
    bstate.nthread = 0;
    pthread_cond_broadcast(&bstate.barrier_cond);
  } else {
    int round = bstate.round;
    while(bstate.round == round) 
      pthread_cond_wait(&bstate.barrier_cond, &bstate.barrier_mutex);
  }

  pthread_mutex_unlock(&bstate.barrier_mutex);