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From: Samuel Tardieu <sam@ada.eu.org>
Subject: Re: Q: How to do memory access with gnat
Date: 1997/07/20
Message-ID: <qw67meleuoc.fsf@esmeralda.enst.fr>#1/1
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Sender: tardieu@esmeralda.enst.fr
References: <easwuowobrigfij.pminews@boavista.berlin.snafu.de>
Mail-Copies-To: sam@ada.eu.org
To: "Michael Erdmann" <boavista@berlin.snafu.de>
Organization: TELECOM Paris
Newsgroups: comp.lang.ada
Date: 1997-07-20T00:00:00+00:00
List-Id: <comp.lang.ada>


>>>>> "Michael" == Michael Erdmann <boavista@berlin.snafu.de> writes:

Michael> In Ada95 i am not able to copy data from an Ada object into a
Michael> some external memory.  Any idea ?

You should try using the predefined generic package
System.Address_To_Access_Conversions. Then given a variable of type
System.Address, you can obtain an access value on your shared data.

Pseudo example:

with Dos_Utils;
with System.Address_To_Access_Conversions;

procedure Test is

   type My_Data is record
      [...]
   end record;

   package A_To_A is new System.Address_To_Access_Conversions (My_Data);
   subtype My_Data_Access is A_To_A.Object_Pointer;
   
   Addr : System.Address;
   Data : My_Data_Access;

begin
   Addr := Dos_Utils.Get_Shared_Memory (Data'Size / 8);
   Data := A_To_A.To_Pointer (Addr);
   [...you can use Data, it is pointing on an object stored in shared mem...]
end Test;

  Sam
-- 
Samuel Tardieu -- sam@ada.eu.org