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From: jerry@jvdsys.stuyts.nl
Subject: Re: Interfacing to void *
Date: 1999/07/19
Message-ID: <FF4BLH.53@stuyts.nl>#1/1
X-Deja-AN: 502875209
Sender: jerry@stuyts.nl (Jerry van Dijk)
References: <37929901.649C0955@worldnet.att.net>
Organization: * JerryWare HQ *, Leiden, Holland
User-Agent: tin/pre-1.4-980226 (UNIX) (Linux/2.2.10 (i586))
Newsgroups: comp.lang.ada
Date: 1999-07-19T00:00:00+00:00
List-Id: <comp.lang.ada>

William Starner <billeug@worldnet.att.net> wrote:

: If I'm trying to interface to a C library that uses this struct

: struct BigNum {
: 	void *ptr;
: 	unsigned int size;
: 	unsigned int allocated;
: };

: how should I interface to void*?

Depends on what you need to do with the result. In the most basic case
you could do something like:

   type BigNum is
      record
         ptr       : System.Address;
         size      : Interfaces.C.unsigned;
         allocated : Interfaces.C.unsigned;
      end record;
   pragma Convention (C, BigNum);

as a void * basically is a memory address and use 
System.Address_To_Access_Conversions to get an access type
to whatever ptr is pointing at.

-- 
-- Jerry van Dijk | Leiden, Holland
-- Team Ada       | jdijk@acm.org
-- see http://stad.dsl.nl/~jvandyk