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From:
Brad Balfour <[log in to unmask]>
Reply To:
Brad Balfour <[log in to unmask]>
Date:
Wed, 13 Nov 1996 11:36:13 -0500
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At 4:59 AM -0500 11/13/96, Ken Garlington wrote:
[snip]
>I was actually planning on trying (on my own time) to create an Ada subset
>using GNAT, that would be applicable to 8-bit and 16-bit microcontroller
>software. Right now, we have to ask for waivers for a lot of these
>applications. If someone has already done some work on defining such a
>subset, I'd like to know how it was derived. Certainly, if we don't come up
>with a version of Ada that doesn't require much (if any RAM), we'll never
>get past using C and assembly for these tiny processors, which seem to pop up
>in all sorts of applications.

[snip again]
>I actually don't see the problem with building a "tiny Ada" or CDL compiler
>under the current rules. You can certainly pass validation using a subset of
>tests, if you can show that the other tests are inappropriate for a given
>target. I would think a target with 256 bytes of RAM, for example, would be
>reasonable grounds for not supporting heap management, etc. However, without
>someone having a compelling reason to try to build such a product, we'll
>never know for sure. The developers of such systems won't use Ada because (a)
>they are usually writing less than 4K of source code. so the advantages of
>Ada are less obvious, and (b) there's no compilers. Compiler vendor's won't
>build compilers because the users aren't begging them to build something.

Sy Wong wrote:
>> To: Jim Moore, ACM Techn. Stds Comm. Chair <[log in to unmask]> 1996.11.2
[snip]
>> Logic do not prevail for a
>> vendor that only caters to the SSS market to develope a compiler for full
>> Ada-95 solely to get validation and then make sure that the customer
>> cannot use the restricted constructs.  The other two listed application
>> areas have similar requirements for the SSS sector where Annex-H
>> restricted compiler can have a market.  In particular, in the EDA market,
>> this subset can serve both as Hardware Design/Description Language (HDL)
>> in addition to programming and can be used as hw/sw Co-Design Language
>> (CDL).

There is a theme running through the above three paragraphs from Ken & Sy
that I don't understand. Both of you seem to be under the impression that
it is important for a compiler targeted at the "commercial 8-bit
microcontroller" market to implement the full Ada language, to be
validated, and then to enforce restrictions on using many features (via
Annex H).

It would seem to me to be much simpler to just:
a) have the compiler process only those features that you want, and
b) ignore formal validation of the compiler

No one else in the commercial marketplace (e.g., automobiles, washing
machines,etc.) worries about whether the compiler for their langauge
(assembly or C) is validated. Why should they care if their Ada compiler is
or not?

If you, the maker of the compiler, want to ensure it's correctness, then
all  obtain a copy of the ACVC, delete those test that don't make sense for
your (subset) compiler, and run the test suite. You can even provide these
results to your customer upon request.

As long as we are not talking about the US DoD -- and we are not -- then
validation is not a requirement at all. Let's not let this impede our
progress into new commercial domains.

Brad


--
Brad Balfour                            SIGAda WWW Server
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