From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,91c8a2ba0b435b28,start
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2003-03-17 11:45:43 PST
Path: 
 archiver1.google.com!news1.google.com!sn-xit-02!sn-xit-03!sn-xit-06!sn-post-01!supernews.com!corp.supernews.com!not-for-mail
From: Brian Palmer <bpalmer@elmco.com>
Newsgroups: comp.lang.ada
Subject: Interfacing Generics with C Pointers
Date: Mon, 17 Mar 2003 13:56:29 +0000
Organization: ELMCO
Message-ID: <v7c9f6sa793403@corp.supernews.com>
User-Agent: KNode/0.7.1
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7Bit
X-Complaints-To: abuse@supernews.com
Xref: archiver1.google.com comp.lang.ada:35420
Date: 2003-03-17T13:56:29+00:00
List-Id: <comp.lang.ada>

I've got a problem where I get in a pointer to a block of memory that was 
allocated in C++.  In addition to the pointer, I get the number of bytes 
that were allocated.  The Ada type that the memory comes in as is a pointer 
to an unconstrained byte array.  Whenever I try to dereference the pointer, 
I get a CONSTRAINT ERROR.  I think the problem is due to the compiler 
trying to access a storage location within the type that tells how many 
bytes are there.  I feel like I could constrain the base type and get 
around the problem, however, this mechanism is used for several different 
size blocks of memory, several hundred times per second, and I don't want 
to have to allocate more memory than necessary.  Any ideas how to access 
unconstrained memory without the compiler looking for that built in 
element?

Any help would be appreciated.

-Brian Palmer