#define N_CLASSES 10

int value_pass;
int nwait = 0;
int nwait_prio[N_CLASSES] = {0,0,...};
sem_t sync[N_CLASSES] = {0,0,...};
sem_t mutex = 1, mutex2 = 1;


int wait(int w_prio, int max_proc){
  int res;

  P(mutex);
  if (nwait >= max_proc){
    V(mutex);
    return -1;
  }else{
    nwait_prio[w_prio]++;
    nwait++;
    V(mutex);
    P(sync[w_prio]);

    P(mutex2);
    res = value_pass;
    nwait--;
    nwait_prio[w_prio]--;
    if (nwait_prio[w_prio]==0) V(mutex);
    V(mutex2);
    return res;
  }
}


int sblock(int s_prio, int value){
  int c, res;

  P(mutex);
  if (nwait_prio[s_prio] > 0){
    res = nwait_prio[s_prio];
    value_pass = value;
    for(c=0; c<res; c++){
      V(sync[w_prio]);
    }
  }else{
    res = 0;
    V(mutex);
  }
  return res;
}