La funzione atomica:

int atomicIncrement (int *var) {
  int tmp = *var;
  *var = tmp + 1;
  return (tmp);
}

puo' essere utilizzata come segue:

typedef struct lock_s {
  int tichekNumber;
  int turnNumber;
} lock_t;

void init (lock_t lock) {
  lock.ticketNumber = 0;
  lock.turnNumber = 0;
}

void lock (lock_t lock) {
  int myTurn = atomicIncrement (&lock.ticketNumber);
  while (lock.turnNumber != myTurn);
}

void unlock (lock_t lock) {
  atomicIncrement (&lock.turnNUmber);
}