#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <stdio.h>
#include <stdlib.h>

#include "opSem.h"               /* opSem.c */

#define Pval -1
#define Vval  1
#define Zval  0

void semaphore (int sem_id, int sem_num, int op)
{
  struct sembuf Ops[1];
  int ok;

  Ops[0].sem_num = sem_num;
  Ops[0].sem_op  = op;
  Ops[0].sem_flg = 0;

  ok = semop(sem_id, Ops, 1);
  if (ok==-1) { perror("semop"); exit(EXIT_FAILURE); }
}

void P(int sem_id, int sem_num) {
  semaphore (sem_id, sem_num, Pval);
}

void V(int sem_id, int sem_num) {
  semaphore (sem_id, sem_num, Vval);
}

void Z(int sem_id, int sem_num) {
  semaphore (sem_id, sem_num, Zval);
}