#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/mman.h>

main() 
{
	int fd ;
	void *virt_addr ;
	int *ptr1, *ptr2, i ;

	fd = open("mydevice", O_RDWR) ;
	if (fd == -1)
	{
		printf("open failed\n") ;	
		exit(-1) ;
	}

	virt_addr = mmap(NULL, 10000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0) ;
	if (virt_addr == MAP_FAILED)
	{
		printf("mmap failed\n") ;
		exit(-1) ;
	}

	ptr1 = (int *) virt_addr ;

	ptr2 = (int *) virt_addr ;

    	printf("ptr1 = %ld, ptr2 = %ld virt_addr=%ld \n",

        	(unsigned long)ptr1, (unsigned long)ptr2,

	        (unsigned long)virt_addr) ;

    	for(i = 0 ; i < 2048 ; i++)
    	{
        	*(ptr1 + i) = i ;
    	}

    	for(i = 0 ; i < 2048 ; i++)
    	{
        	printf("%d ", *(ptr2 + i)) ;
    	}

	munmap(virt_addr, 80) ;

	close(fd) ;
	
	return 0 ;
}