#include <stdio.h>
    #include <stdlib.h>
    #include <errno.h>
    #include <sys/types.h>
    #include <sys/ipc.h>
    #include <sys/sem.h>

    int main(void)
    {
        key_t key;
        int semid;


static struct sembuf DecrR = {0,-1,SEM_UNDO};
static struct sembuf IncrR = {0,1,SEM_UNDO};
static struct sembuf DecrW = {1,-1,SEM_UNDO};
static struct sembuf IncrW = {1,1,SEM_UNDO};
static struct sembuf DecrCl = {2,-1,SEM_UNDO};
static struct sembuf IncrCl = {2,1,SEM_UNDO};
static struct sembuf DecrC = {3,-1,SEM_UNDO};
static struct sembuf IncrC = {3,1,SEM_UNDO};

	key = ftok("reader.c", 'X');
	semid= semget(key,4,IPC_CREAT | 0600);
//	semctl(semid,0,SETVAL,1);
//	semctl(semid,1,SETVAL,1);
//	semctl(semid,2,SETVAL,1);
//	semctl(semid,3,SETVAL,1);

int i;
int j;
for(i = 0; i<5; i++){
semop(semid,&IncrR,1);
semctl(semid,2,SETVAL,0);

j=semctl(semid, 3, GETVAL, 0);
if(j==0){
semctl(semid,1,SETVAL,0);
semop(semid, &IncrC, 1);
}

semctl(semid,2,SETVAL,1);
semop(semid, &DecrR, 1);

printf("READING\n");
sleep(2);
printf("DONE READING\n");
printf("test");
semctl(semid,2,SETVAL,0);

semop(semid, &DecrC, 1);

j=semctl(semid, 3, GETVAL, 0);
if(j==0){
semctl(semid,1,SETVAL,1);
semop(semid, &DecrCl, 1);
}
sleep(4);


}


        return 0;
    }