#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/mman.h>
#include <sys/stat.h>        /* mnemonici in mode */
#include <fcntl.h>           /* mnemonici in oflag */
#include <semaphore.h>

#define BUF_SIZE 5 


void main (int argc, char **argv)
{ 	
	int fd, i, j, pid, size=(BUF_SIZE+1)*sizeof(float); 
	float* buffer;
	sem_t* mutex3; 
	sem_t* db; 
	int* nr_lett;
	float value, elto=0;
	time_t t;

	srand((unsigned) time(&t));

	mutex3=sem_open("mutex3", O_CREAT, S_IRUSR | S_IWUSR, 1);	/* creo i semafori */
	db=sem_open("db", O_CREAT, S_IRUSR | S_IWUSR, 1);
	
	fd = shm_open("mymem3",  O_CREAT | O_EXCL |O_RDWR, S_IRUSR | S_IWUSR);	/* creo la SHM */
 	ftruncate(fd,size);
 	buffer = mmap(NULL ,size,PROT_READ | PROT_WRITE, MAP_SHARED ,fd, 0);

	nr_lett=(int*)(buffer+BUF_SIZE);

	*nr_lett=0;
 	for(i=0;i<BUF_SIZE;i++) buffer[i]=(float)(rand() % 50);/*scrivo il database*/	
	printf("scritto archivio\n");	
	
	while(1){
	   sleep(1);
	   sem_wait(db); 	
	   for(i=0;i<BUF_SIZE;i++) {buffer[i]=(float)(rand() % 50);printf("db %2.1f",buffer[i]);}
	   printf(" Ho scritto l'archivio\n");	
	   sem_post(db);

	}
}