#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <semaphore.h>


#define P sem_wait
#define V sem_post

#define N 10

sem_t empty;
sem_t full;

int w = 0; // write index
int r = 0; // read index

int buffer[N]; // buffer

void* read_buffer(void* data)
{

 while(1)
    {

        P(&full);

        printf("--------------- Read ---------------\n");
        printf("Read [%d] : %d\n\n", r, buffer[r]);

        buffer[r] = -1;

        r = (r + 1) % N;

    V(&empty);

    sleep(2);

    }
    pthread_exit(NULL);

}


void* write_buffer(void* data)
{
    int cpt = 0;

    while(1)
    {

        P(&empty);

        printf("--------------- Write ---------------\n");
        buffer[w] = cpt;
        printf("Write [%d] : %d\n\n", w, cpt);
        w = (w + 1) % N;

    V(&full);
        cpt++;
    sleep(2);

    }

        pthread_exit(NULL);

}


int main()
{

    for (int i = 0; i <N ; i++)
{
    buffer[i] = -1 ;

}
    pthread_t writer;
    pthread_t reader;

    // on initialise les deux sémaphore,
    sem_init(&empty, 0, N);
    sem_init(&full, 0, 0);

    // on crée les threads
    pthread_create(&writer, NULL, write_buffer, NULL);
    pthread_create(&reader, NULL, read_buffer, NULL);

    // pn attends que les threads se terminent avant de fermer le programme
    pthread_join(writer, NULL);
    pthread_join(reader, NULL);

    return 0;
}