Re: Calling C time function from ADA-95

[Markus Kuhn <Markus.Kuhn@cl.cam.ac.uk>]

Charles Hixson wrote:
> I think that times should be kept on a kind of sliding scale.  Say
> seconds for the current decade, minutes for the current century, hours
> for the current 100 centuries.  Days for the current 10,000 centuries.
> Etc.

That sounds like a revolutionary new concept, but somehow I remember
having heard one of our Computer Science professors telling us already
about such advanced mechanisms for representing scalar values.
Isn't this stuff called "floating point numbers" or so?  :-)

> That should be sufficient overkill for ANYONE that would be
> satisfied by the current date structure anyway.

Just use a 64-bit integer counter for the seconds since some epoch,
which will last for the next 290 billion years (and goes backwards
far beyond the big bang). Add a 32-bit counter with the number
of nanoseconds since the last second started, and you get a
resolution that is an order of magnitude better than your CPU
frequency and the accuracy of good atomic clocks. The 32-bit
nanosecond counter has the nice property that inserted
leap seconds in your time scale (say UTC) can be represented
nicely as values 10**9..2*10**9-1.

Markus

-- 
Markus G. Kuhn, Security Group, Computer Lab, Cambridge University, UK
email: mkuhn at acm.org,  home page: <http://www.cl.cam.ac.uk/~mgk25/>