Re: Simple Real_Time.Time_Span question

[dewar@gnat.com]

In article <707v7m$3aa$1@nnrp1.dejanews.com>,
  dennison@telepath.com wrote:
> In article <F0wCFH.In.0.-s@inmet.camb.inmet.com>,
>   stt@houdini.camb.inmet.com (Tucker Taft) wrote:
> > dennison@telepath.com wrote:
> >
> > : ...
> > : Even though this code has to be portable, I probably would have
considered
> > : cheating and using Duration if I could have found any documentation from
my
> > : compiler vendor on how it is implemented. Unfortunately, there seem to be
> > : *no* documentation requirements on Duration (unlike all *other*
predefined
> > : types), so my vendor didn't bother to document it. Lucky me.
> >
> > There should be an "annex M" which contains such information.
> >
>
> Yes, there is an annex M. No, it does not contain that information. It has
> entries for the predefined integer types declared in Standard (13), and the
> predefined floating-point types declared in Standard (17), but none for the
> predefined fixed-point types declared in Standard. As far as I can tell from
> the LRM's annex M, there are *no* documentation requirements for Duration.
> I'd be happy to be proven wrong (cuz then I could go bitch at my vendor).


Well most certainly Duration'Small must be documented, this is perfectly clear
from the RM. In M, we have

    2  Whether or not each recommendation given in Implementation Advice
       is followed.  See 1.1.2(37).

Certainly one hopes that this requirement is followed!

In section 9.6, we have

                            Implementation Advice

30   Whenever possible in an implementation, the value of Duration'Small
should be no greater than 100 microseconds.

So clearly this must be documented, and that is really what you are interested
in here. The GNAT RM contains this required documentation, and there you can
find:

@findex Duration'Small
@item 9.6(30-31): Duration'Small
@sp 1
@cartouche
Whenever possible in an implementation, the value of @code{Duration'Small}
should be no greater than 100 microseconds.
@end cartouche
Followed. (@code{Duration'Small} = 10**(-9)).


(This is the original texi source, from which we make HTML, postscript, and
the info file that emacs can view, as well as OS/2 and WinNT format help
files. The cartouche makes a nice box around the answer :-)

Robert Dewar
Ada Core Technologies

-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/       Search, Read, Discuss, or Start Your Own