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From: Matthew Heaney <matthew_heaney@acm.org>
Subject: Re: Simple Real_Time.Time_Span question
Date: 1998/10/14
Message-ID: <m3r9wb1p8r.fsf@mheaney.ni.net>#1/1
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References: <6vvsgo$rvo$1@nnrp1.dejanews.com>
 <700usk$cht$1@nnrp1.dejanews.com> <702b25$30a$1@nnrp1.dejanews.com>
NNTP-Posting-Date: Wed, 14 Oct 1998 09:05:45 PDT
Newsgroups: comp.lang.ada
Date: 1998-10-14T00:00:00+00:00
List-Id: <comp.lang.ada>

dennison@telepath.com writes:

> In article <700usk$cht$1@nnrp1.dejanews.com>,
>   dewar@gnat.com wrote:
> 
> > It is odd for a compiler not to choose a sufficient precision for Duration
> > to accurately represent a Time_Span value. Certainly in the case of GNAT,
> > Duration is represented in nanoseconds, and you will not lose any precision
> > following the conversion path you suggest.
> 
> I hate to drag my own thread off topic, but how did you do that? According to
> 9.6(27) Duration has to represent up to 86,400 seconds. For a "classical"
> implementation of a fixed-point type that can represent both 86,400 and
> 0.000_000_001, my poor calculations tell me you'd need at least 47 bits. On a
> 32-bit processor that would be tricky.

GNAT uses 64 bits to implement fixed point types.  One of the reasons
this is nice is that you can have an unsigned, 32 bit fixed point type.