Yo Hal! On Fri, 10 Mar 2017 00:59:49 -0800 Hal Murray <hmur...@megapathdsl.net> wrote:
> > I'm now leaning that way too. And two ways to make an l_fp, one
> > starting with int's and the other uint's.
>
> Be careful with making negative values. The case I'm worried about
> is dropping the carry out of the low half.
The code has a normalize_tspec() ir prolly needs a normalize_lp().
> > The npd code is gonna be OK, the problem is that the NTP wire
> > protocol for timestamps is in 32 bits!
>
> Why is that a problem?
Because a RasPi has no RTC. When it starts up it is always 1970
again. When 2036 comes, how will the RasPi know it is 2036 and not
1970?
> To convert between NTP and Unix... Until 2036, you just add/sub
> JAN_1970. After 2036 add/sub JAN_1970 and 1<<32 if T < build date.
> (Or something close to that.)
I love the lcak of confidence you have there. Could should be obvious.
> >> Does the current code have the right variable? Have you found it?
> >> Is there more than one place that does NTP to Unix conversion?
> > Sort of. The conversion constant is JAN_1970. That is defined in
> > include/ ntp_calendar.h.
>
> That constant doesn't have anything to do with calendars. I'm not
> sure where it should go.
Good enough place for now.
> In the long run, it's more complicated. See above.
Oh, yeah.
> > There is a macro to do the conversion from timestamp to NTP Epoch:
> > tspec_stamp_to_lfp(), but it is not always used.
>
> > There look to be just two places the conversion from NTP Epoch is
> > done: ntpcal_ntp_to_time() and ctl_putfs(). And the later not even
> > using l_fp, it uniquely uses tstamp_t which is seconds based on NTP
> > Epoch.
>
> ctl_putfs is only used to printout leap second dates.
Looks to me like it is creating an NTP mode 6 message in wire format.
To change that you would need to change the mode 6 protocol.
> I don't see any
> reason to involve NTP date formats or epochs. From a quick glance,
> the NTP in the comment where it is defined looks bogus. I'll clean
> that up if you want to unload a nice small chunk, but it looks like
> you have already done something in that area.
I have some ideas, but if it makes sense to you, go ahead.
> I haven't sorted out ntpcal_ntp_to_time yet.
Easy, it is just converting a 32 bit NTP Epoch time stamp into a
POSIX Epoch time stamp. It is not worth a lot of time it is only used
in libntp/prettydate.c common_prettydate().
ntpcal_ntp_to_time() could become a static in libntp/prettydate.c
RGDS
GARY
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