how do change this Dining philosopher's solution using pthread to SEMAPHORES

// // dp_main.c // dining_philosophers // #include  #include  #include  #include  #include  #include  #define NUM_PHILO 5 #define MAX_SLEEP_TIME 2 #define MAX_EATEN 3 int total_iterations = 0; typedef enum {THINKING, HUNGRY, EATING} STATE; pthread_t tid[NUM_PHILO]; STATE state[NUM_PHILO]; long thread_id[NUM_PHILO]; int haveEaten[NUM_PHILO]; // condition variables and associated mutex lock pthread_cond_t cond_vars[NUM_PHILO]; pthread_mutex_t mutex_lock; const char* toString(STATE state, int haveEaten) { static char buf[20]; switch(state) { case THINKING: return "thinking"; case HUNGRY: return "*Hungry*"; case EATING: memset(buf, 0, sizeof(buf)); snprintf(buf, sizeof(buf), "EATING (%d)", haveEaten); return buf; default: return "-------- invalid state --------"; } } void showAllPhilosophers() { printf("------------------------------------------------------------------------- "); for (long i = 0; i < NUM_PHILO; ++i) { printf("%10s | ", toString(state[i], haveEaten[i])); } printf(" "); } void nap(const char* msg, int time) { /* printf("%s ", msg); */ sleep(time); } void thinking(int thinking_time) { nap("thinking", thinking_time); } void eating( int eating_time) { nap("eating", eating_time); } long onleft(long number) { return (number + NUM_PHILO - 1) % NUM_PHILO; } long onright(long number) { return (number + 1) % NUM_PHILO; } void hungry_chopsticksAvail_eat(long i) { // eat when I'm hungry and my neighbors aren't eating if (state[i] == HUNGRY && state[onleft(i)] != EATING && state[onright(i)] != EATING) { ++haveEaten[i];/Users/williammccarthy/dev/CSUF/cs 351/dining_philosophers/dining_philosophers/dp_main.c state[i] = EATING; showAllPhilosophers(); pthread_cond_signal(&cond_vars[i]); // signal thread i it is now eating } } void wants_to_pickup_chopsticks(long number) { pthread_mutex_lock(&mutex_lock); state[number] = HUNGRY; hungry_chopsticksAvail_eat(number); // wait for signal to eat while (state[number] != EATING) { pthread_cond_wait(&cond_vars[number], &mutex_lock); } pthread_mutex_unlock(&mutex_lock); } void wants_to_return_chopsticks(long number) { pthread_mutex_lock(&mutex_lock); state[number] = THINKING; hungry_chopsticksAvail_eat(onleft(number)); // signal HUNGRY left/right neighbors to eat hungry_chopsticksAvail_eat(onright(number)); pthread_mutex_unlock(&mutex_lock); } void* philosopher(void* param) { long number = *(long *)param; int sleep_time; int times_through_loop = 0; srandom((unsigned)time(NULL)); while (haveEaten[number] < MAX_EATEN) { sleep_time = (int)((random() % MAX_SLEEP_TIME) + 1); thinking(sleep_time); wants_to_pickup_chopsticks(number); sleep_time = (int)((random() % MAX_SLEEP_TIME) + 1); eating(sleep_time); wants_to_return_chopsticks(number); ++times_through_loop; } return NULL; } void init() { // requires -std=C99 or -std=C11 compile-flag for (int i = 0; i < NUM_PHILO; i++) { state[i] = THINKING; haveEaten[i] = 0; thread_id[i] = i; pthread_cond_init(&cond_vars[i], NULL); } pthread_mutex_init(&mutex_lock, NULL); } int main(int argc, const char** argv) { init(); printf("========================================================================= "); printf("| ====== PHILOSOPHERS ====== | "); printf("========================================================================= "); printf(" Phil_0 | Phil_1 | Phil_2 | Phil_3 | Phil_4 | "); showAllPhilosophers(); for (int i = 0; i < NUM_PHILO; i++) { pthread_create(&tid[i], 0, philosopher, (void *)&thread_id[i]); } for (int i = 0; i < NUM_PHILO; i++) { pthread_join(tid[i], NULL); } printf(" \t\t...done. "); return 0; }