#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <sys/ipc.h>
#include <sys/types.h>
#include <string.h>


int main(int argc, char *argv[])
{
	int	pid, fd_fifo, cont;
	int sem_id, shm_id;
	struct sembuf  dec2={0,-2,0};
	int *mem_cond;
	sem_id = atoi(argv[1]);
	shm_id = atoi(argv[2]);
	pid = getpid();
	fd_fifo = open(argv[3], O_WRONLY);
	write(fd_fifo, &pid, sizeof(int));
	mem_cond = (int *)shmat(shm_id, 0,0); 
	cont = *mem_cond;
	printf("\n Pid = %d: memoria condivisa = %d\n", pid, cont);
	while(1)
	{	
		semop(sem_id, &dec2, 1);
		printf("\n Pid = %d: memoria condivisa = %d\n", pid, *mem_cond);
		cont = cont * 4;
		printf("\n cont = %d\n", cont);
		*mem_cond = cont;
	}
}