Re: Adjustable wallclock (get/settimeofday, adjtimex)?

[daniel.neri@xxxxxxxxxxx (Daniel Néri)]

  Hello,

Stanislav Meduna <stano@xxxxxxxxxx> writes:

> I need to implement a NTP-like model soon, which means:
>
> - gettimeofday with best possible resolution and negligible
>   call delay
> - settimeofday
> - the ability to speed up or slow the clock (adjtime/adjtimex
>   or similar), both permanently or until the requested offset
>   is compensated for; the clock must not go backward

I've described my approach in an older thread on this list:

  http://thread.gmane.org/gmane.os.ecos.general/25842/

I never bothered with sub-second resolution for setting time
(settimeofday), so I just use cyg_libc_time_settime.

> - the ability to initialize from / store the current time to
>   a battery-backed device

I've used a hybrid between the emulated wallclock and a "real" wallclock
device driver -- it only reads absolute time from the h/w via
Cyg_WallClock::init_hw_seconds and writes via
Cyg_WallClock::set_hw_seconds. Otherwise, it works like the emulated
wallclock driver.


Best regards,
Daniel



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