In message <20090517031525.292e7b...@ip-64-139-1-69.sjc.megapath.net>, Hal Murr ay writes:
>This is one of the reasons why I was looking for a low-cost FPGA on PCI board >with some way to get a couple of external inputs. > >Things get interesting if your hardware splits a 64 bit read into 2 32 bit >transfers. Many years ago, all Intel chips did that. I don't know about >today. You don't need a 64bit counter in the first place. You are going to have a thread around anyway, which adjusts your clock based on the NTP PLL's output, that thread can maintain your "reference time" so that a 32 bit counter will never overflow. Which, I might add, is _exactly_ how FreeBSD does it :-) Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
