[ntp:questions] Slightly OT: Looking for good GPS PCI time sources

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Sat Jul 7 20:10:55 UTC 2007


>One consideration might be whether the cards in question allow readout
>of the time as a single atomic operation -- if they don't, one can't
>(for example) read the time without worrying about locking...

You don't need a lock.  The standard trick is to read the
high-bits, low-bits, then high-bits again.  Then compare the
two high-bits readings.  If they are the same you are done.
If not, it overflowed from the low to high bits between
readings.  Try again.

-- 
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