H. Peter Anvin wrote: > H. Peter Anvin wrote: >> Frédéric BERNON wrote: >>> microseconds? Which ones? I thought most were in milliseconds. Which >>> lwIP release do you use? >> >> Sorry, I might be mistaken. I'm looking at 1.3.0. Either way, the >> question still holds. >> > > I guess I really should explain the background. > > I'm looking at using this in a raw PC BIOS environment, where the only > *guaranteed* timer only has a 55 ms granularity. There are ways to get > better resolution by going straight to the hardware, but PC hardware > being what it is (utter crap) that's a risky thing for trying to make > something that works on all platforms.
In practice I don't think there are any timers which require better than 100ms granularity, and I doubt a little inaccuracy delaying a timeout by up to 55ms would really affect much (as long as it isn't up to 55ms _early_). Although in any case, PC hardware is actually pretty standard - with backward compatibility still present for obscenely ancient devices. Usually you can use the Periodic Interval Timer anywhere. You can see a usage example in eCos here(hal_pc_clock_initialize and hal_pc_clock_read): http://ecos.sourceware.org/cgi-bin/cvsweb.cgi/ecos/packages/hal/i386/pcmb/current/src/pcmb_misc.c?rev=1.9&content-type=text/x-cvsweb-markup&cvsroot=ecos with some info from: http://ecos.sourceware.org/cgi-bin/cvsweb.cgi/ecos/packages/hal/i386/pcmb/current/include/pcmb_intr.h?rev=1.5&content-type=text/x-cvsweb-markup&cvsroot=ecos It uses interrupt IRQ0 i.e. 32. Jifl -- eCosCentric Limited http://www.eCosCentric.com/ The eCos experts ** Visit us at ESC Silicon Valley <http://www.embedded.com/esc/sv> ** ** April 15-17 2008, Booth 3012, San Jose McEnery Convention Center ** Barnwell House, Barnwell Drive, Cambridge, UK. Tel: +44 1223 245571 Registered in England and Wales: Reg No 4422071. ------["Si fractum non sit, noli id reficere"]------ Opinions==mine _______________________________________________ lwip-users mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/lwip-users
