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PARSE reference clock driver: This directory contains the files making up the parser for the parse refclock driver. For reasonably sane clocks this refclock drivers allows a refclock implementation by just providing a conversion routine and the appropriate NTP parameters. Refclock support can run as low a 3k code with the parse refclock driver. The modules in here are designed to live in two worlds. In userlevel as part of the xntp daemon and in kernel land as part of a STREAMS module or, if someone gets to it, as part of a line discipline. Currently only SunOS4.x/SunOS5.x STREAMS are supported (volunteers for other vendors like HP?). This structure means, that refclock_parse can work with or without kernel support. Kernelsupport increases accuracy tremendingly. The current restriction of the parse driver is that it only supports SYSV type ttys and that kernel support is only available for Suns right now. Three kernel modules are part of this directory. These work only on SunOS (SunOS4 and SunOS5). SunOS4 (aka Solaris 1.x): parsestreams.loadable_module.o - standard parse module for SunOS 4 Both modules can be loaded via modload <modulename>. SunOS5 (aka Solaris 2.x): parse - auto loadable streams module To install just drop "parse" into /kernel/strmod and start the daemon (SunOS5 will do the rest). The structure of the parse reference clock driver is as follows: ntpd - contains NTP implementation and calls a reference clock 127.127.8.x which is implemented by refclock_parse.c - which contains several refclock decriptions. These are selected by the x part of the refclock address. The lower two bits specify the device to use. Thus the value (x % 4) determines the device to open (/dev/refclock-0 - /dev/refclock-3). The kind of clock is selected by the mode parameter. This parameter selects the clock type which deterimines how I/O is done, the tty parameters and the NTP parameters. refclock_parse operates on an abstract reference clock that delivers time stamps and stati. Offsets and sychron- isation information is derived from this data and passed on to refclock_receive of xntp which uses that data for syncronisation. The abstract reference clock is generated by the parse* routines. They parse the incoming data stream from the clock and convert it to the appropriate time stamps. The data is also mapped int the abstract clock states POWERUP - clock has no valid phase and time code information NOSYNC - Time code is not confirmed, phase is probably ok. SYNC - Time code and phase are correct. A clock is trusted for a certain time (type parameter) when it leaves the SYNC state. This is derived from the observation that quite a few clocks can still generate good time code information when losing contact to their synchronisation source. When the clock does not reagain synchronisation in that trust period it will be deemed unsynchronised until it regains synchronisation. The same will happen if xntp sees the clock unsynchronised at startup. The upper bit of x specifies that all samples delivered from the clock should be used to discipline the NTP loopfilter. For clock with accurate once a second time information this means big improvements for time keeping. A prerequisite for passing on the time stamps to the loopfilter is, that the clock is in synchronised state. parse.c These are the general routines to parse the incoming data stream. Usually these routines should not require modification. clk_*.c These files hole the conversion code for the time stamps and the description how the time code can be parsed and where the time stamps are to be taken. If you want to add a new clock type this is the file you need to write in addition to mention it in parse_conf.c and setting up the NTP and TTY parameters in refclock_parse.c. Further information can be found in parse/README.parse and the various source files. Frank Kardel