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From: Mats Karlssohn <mats@mida.se>
Newsgroups: comp.lang.ada
Subject: Re: records containing variable length arrays [long]
Date: Tue, 19 Jun 2001 13:43:11 +0200
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Jeffrey Carter wrote:
%<
> You can probably avoid the conversion of the pointer. Given
%<
> type Message_Ptr is access all Message;
> pragma Convention (C, Message_Ptr);
> 
> procedure Get (Ptr : out Message_Ptr; Length : out Interfaces.C.Int);
> pragma Import (C, Get, "get");

Hmmm, I feel I really need to do some reading on and experimenting with
the import/export and convention pragmas. If it's possible to convert
the C pointer in this way the solution of the problem will become wery
nice and uncluttered...

%<
> > Is there a way to explicitly put at least the CRC element into the
> > representation clause ? My experiments haven't gotten me anywhere
> > on this part.
> 
> Only if it comes before the variable-length part of the record. The
> values used in a record representation clause have to be static, which
> means known at compile time.

Oh... that's too bad. Well, I'll have to see what I might do about it.
I guess that I could split the record declaration into three or four
pieces and also declaring a few constants along with them. But it I
worry about the execution times for this piece so I'll probably just
omit the representation for the last part and add a few testcases that
will show if the assumptions is correct.


Thanks anyway, my vacation was nice (and well earned).

-- 
Mats Karlssohn, developer                         mailto:mats@mida.se  
Mida Systemutveckling AB                          http://www.mida.se
Box 64, S-732 22 ARBOGA, SWEDEN
Phone: +46-(0)589-89808   Fax: +46-(0)589-89809