#include<stdio.h>
#include<fcntl.h>
#include<semaphore.h>

int main(){
    int n;
    printf("\nENter buffer size: ");
    scanf("%d", &n);

    int buffer[n];
    int in =0, out= 0;

    sem_unlink("/mutex");
    sem_unlink("/empty");
    sem_unlink("/full");

    sem_t *mutex = sem_open("/mutex", O_CREAT, 0644, 1);  
    sem_t *empty = sem_open("/empty", O_CREAT, 0644, n);  
    sem_t *full  = sem_open("/full",  O_CREAT, 0644, 0);

    int ch, item;
    while(1){
        printf("\n--- Producer Consumer ---");
        printf("\n1. Produce (Write)");
        printf("\n2. Consume (Read)");
        printf("\n3. Exit");
        printf("\nEnter choice: ");
        scanf("%d", &ch);

        if(ch==1){
            printf("\nEnter item to write: ");
            scanf("%d", &item);

            sem_wait(empty);
            sem_wait(mutex);
            buffer[in]= item;
            printf("\nProduced: %d at buffer[%d]", item, in);
            in = (in+1)%n;
            sem_post(mutex);
            sem_post(full);

        }

        else if(ch==2){
       
            sem_wait(full);
            sem_wait(mutex);
            item = buffer[out];
            printf("\nconsumed: %d at buffer[%d]", item, out);
            out = (out+1)%n;
            sem_post(mutex);
            sem_post(empty);

        }

        else if (ch == 3) {
            break;
        }
        else {
            printf("Invalid choice\n");
        }

    }

    sem_close(mutex); sem_close(full); sem_close(empty);
    sem_unlink("/mutex");
    sem_unlink("/empty");
    sem_unlink("/full");
    return 0;
}