green_t *dequeue_cond(green_cond_t *cond){
  green_t *tmp = cond->queue;
  if(tmp == NULL){
    return NULL;
  }else{
  cond->queue = cond->queue->next;
  tmp->next = NULL;
  return tmp;
  }
}

void enqueue_cond(green_t * thread, green_cond_t *cond){
  green_t *tmp = cond->queue;
  if(tmp == NULL){
    cond->queue = thread;
  }else{
    while(tmp->next != NULL){
      tmp = tmp->next;
    }
    tmp->next = thread;
  }
}