#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>

#include <fcntl.h>
#include <string.h>
#include <unistd.h>

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

#define MAP_SIZE			4096UL
#define MAP_MASK 			(MAP_SIZE - 1)

#define DEV_MEM				"/dev/mem"

static unsigned long			addr = 0;
static unsigned long			len = 0x10;

int main()
{
    int			ii;
    int			fd;
    unsigned long	paddr = 0;
    unsigned long	offset;
    unsigned long	*map_lbase;

    if(getpagesize() != MAP_SIZE) {
	fprintf(stderr, "Incorrect page size\n");
	exit(1);
    }

    if((fd = open(DEV_MEM, O_RDWR | O_SYNC)) == -1) {
	fprintf(stderr, "cannot open %s - are you root?\n", DEV_MEM);
	exit(1);
    }

    // Calculate the page number, and the offset within the page.
    paddr  = addr & ~MAP_MASK;
    offset = addr &  MAP_MASK;

    // Map that page.
    map_lbase = (unsigned long *)mmap(NULL, MAP_SIZE,
	    PROT_READ | PROT_WRITE, MAP_SHARED, fd, paddr);
    if((long)map_lbase == -1) {
	perror("cannot mmap");
	exit(1);
    }

    // Get a pointer to the offset within the page.
    map_lbase += offset / 4;

    // Dump the requested bytes.
    for(ii = 0; ii < len; ii++) {
	if(ii % 4 == 0) {
	    printf("%08lx: ", addr + (ii * sizeof(unsigned long)));
	}
	printf("%08lx ", map_lbase[ii]);
	if(ii % 4 == 3) {
	    printf("\n");
	}
    }
    if((ii % 4) != 0) {
	printf("\n");
    }

    exit(0);
}

/*
 * Local Variables:
 *   mode: c
 *   tab-width: 8
 *   c-basic-offset: 4
 *   indent-tabs-mode: t
 * End:
 *
 * vim:ts=8:sw=4:sts=4
 */