#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include "display.h"

int main()
{
    struct sembuf up = {0, 1, 0};
    struct sembuf down = {0, -1, 0};

    int v1, v2, v3, v4;
    int i;

    //Create Semaphore
    int mySem = semget(IPC_PRIVATE, 1, 0600);
    v1 = semctl(mySem, 0, GETVAL);
    int mySem2 = semget(IPC_PRIVATE, 1, 0600);

    //Up
    semop(mySem, &up, 1);
    v2 = semctl(mySem, 0, GETVAL);
    //semop(mySem2, &up, 1);

    if (fork())
    {
        for (i=0;i<10;i++)
        {
            //Down
            semop(mySem, &down, 1);
            v3 = semctl(mySem, 0, GETVAL);

            display("ab");

            //Up
            semop(mySem2, &up, 1);
            v2 = semctl(mySem, 0, GETVAL);
        }
        wait(NULL);
    }
    else
    {
        for (i=0;i<10;i++)
        {
            //Down
            semop(mySem2, &down, 1);
            v3 = semctl(mySem, 0, GETVAL);

            display("cd\n");

            //Up
            semop(mySem, &up, 1);
            v2 = semctl(mySem, 0, GETVAL);
        }

        //Destroy
        semctl(mySem, 0, IPC_RMID);
        v4 = semctl(mySem, 0, GETVAL);
        semctl(mySem2, 0, IPC_RMID);
    }

    return 0;
}