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From: kilgallen@eisner.decus.org (Larry Kilgallen, LJK Software)
Newsgroups: comp.lang.ada
Subject: Re: An observation of Ada (may offend)
Message-ID: <1995Mar28.120720.9512@eisner>
Date: 28 Mar 95 12:07:20 -0500
References: <3l640c$308@miranda.gmrc.gecm.com>
Organization: DECUServe
Date: 1995-03-28T12:07:20-05:00
List-Id: <comp.lang.ada>

In article <3l640c$308@miranda.gmrc.gecm.com>, bill@valiant.gmrc.gecm.com (R.A.L Williams) writes:
> In article <1995Mar17.180137.9394@eisner> Larry Kilgallen wrote:
> : In article <3kbkm1$41o@miranda.gmrc.gecm.com>, bill@valiant.gmrc.gecm.com (R.A.L Williams) writes:
>
> : > b. No bit level manipulation (fixed in Ada95 but only for unsigned
> : > ie. mod INTEGERs, I can't test a sign bit, not that I need to) HCTBAEL.
>
> : Well some of us don't have Ada95 scheduled for our platforms...
> : ...but I find that when I need to manipulate bits it is specific bit
> : fields rather than generic bit-algebras :-).  Representation clauses
> : in Ada are marvelous (although I have used similar capabilities from
> : other languages which don't happen to be codified in their standards).
>
> I agree that the representation clauses defined in the LRM are splendid,
> the problem is that they are *optional*. I don't know what the situation
> is now, but when I last did a lot of work in Ada many compilers had only
> a fragmentary coverage.

Well, since the compiler _I_ use has them, who cares about the rest of
you :-) :-) :-).

Actually, if implementation of representation clauses was specified as
optional (I cannot find that statement), the Ada83 author(s) presumably
felt they were hard to accomplishment and would require market pressure
to cause implementation.  At least (unlike Pascal) the syntax for adding
them is _standardized_, so once you have convinced your vendor, the
implementation they provide will be compatible.

> Most of the time, as you say, bit fields are adequate, but how would you
> implement ECC alogorithms or maximal length sequence generators for instance?

Ah, that's just it.  I don't know enough to work on such problems :-).

Larry Kilgallen