#!/usr/bin/python
import mmap
import os
import struct
import time
 
def main():
    # Open the file for reading
    fd = os.open('/tmp/mmaptest', os.O_RDONLY)
 
    # Memory map the file
    buf = mmap.mmap(fd, mmap.PAGESIZE, mmap.MAP_SHARED, mmap.PROT_READ)
 
    i = None
    s = None
 
    while 1:
        new_i, = struct.unpack('i', buf[:4])
        new_s, = struct.unpack('3s', buf[4:7])
 
        if i != new_i or s != new_s:
            print 'i: %s => %d' % (i, new_i)
            print 's: %s => %s' % (s, new_s)
            print 'Press Ctrl-C to exit'
            i = new_i
            s = new_s
 
        time.sleep(1)
 
 
if __name__ == '__main__':
    main()