(c) 2016 Joerg Dorchain <joerg@dorchain.net>

Licenced under GNU GPL v2 or later

This program reads input from a charcter device where presumably a DCF77
receiver is connected to.
The input is parsed and written to a shared memory segment, where ntp can
pick it up for further timekeeping.

The main motivation was the the builtin parse driver for ntp  could
crash ntp, e.g. when weird bits came in at weird timing in bad receiving
conditions, and to feed dcf time to chrony.

Bug reports and contributions are welcome, esp. for making the code more
portable.

Works with USB Gude expert Mouse Clock II

You may try different baud rates. One installation only works
with 4800baud.

Put this as DAEMON_ARGS in /etc/default/dcfshm, e.g.
DAEMON_ARGS="-b 4800"

Example ntp.conf snippet:

server 127.127.28.0     # SHM driver fed by dcfshm 
fudge 127.127.28.0 time1 0.450 refid DCFa