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From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: CRC in Ada?
Date: 1997/03/12
Message-ID: <EACHUS.97Mar12101336@spectre.mitre.org>#1/1
X-Deja-AN: 224947365
References: <1997Mar2.220652@nova.wright.edu> <1997Mar5.131846.1@eisner>
Organization: The Mitre Corp., Bedford, MA.
Newsgroups: comp.lang.ada
Date: 1997-03-12T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <dewar.858095506@merv> dewar@merv.cs.nyu.edu (Robert Dewar) writes:

  > That's a pretty marginal optimization. Maybe Geert makes subtypes
  > Positive_Float, but of all the code we ever had submitted to us,
  > no one ever bothered to do this, they just used Float.

  > Still it can go on the list, it's way down there in priority though,
  > there are MANY more important optimizations ahead of it!

   Let me put an optimization way ahead of it on the list and see if
anyone is interested...

   The easiest way of dealing with the A.5.1(37-42) requirements in a
portable manner is the one currently taken by GNAT--explicit code.
However, most of these requirements will be met by any IEEE conforming
implementation.  So it should be possible to have two versions of the
elementary functions packages, one which assumes good underlying math
libraries, and one which does not.

   Note that the hard work here can be done completely separately from
other compiler maintenance and enhancement activities.  It involves
writing some test code and running it on a lot of different
platforms. (The way I envision this is a set of alternate bodies, and
a test program which validates the elisions.  Of course, the ultimate
would be a test program that generated a tailored version of the
bodies which matched the particular hardware.)

   
--

					Robert I. Eachus

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