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From: jsanchor@my-dejanews.com
Subject: System.Address_to_Access_Conversions
Date: 1998/07/13
Message-ID: <6odddl$k94$1@nnrp1.dejanews.com>#1/1
X-Deja-AN: 371018231
Organization: Deja News - The Leader in Internet Discussion
X-Article-Creation-Date: Mon Jul 13 16:42:29 1998 GMT
Newsgroups: comp.lang.ada
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Date: 1998-07-13T00:00:00+00:00
List-Id: <comp.lang.ada>

Hello Everyone:  In my program I have some system address and I have to move
data to it. I am using access types to do this. I don't want to use Unchecked
conversion. So I started looking at a new feature Ada95 has
System.Address_to_Access_Conversions. I have

type Dummy_Type is tagged private;
type Ptr_to_Data_Type is access all Dummy_Type'class;

private
  type Dummy_Type is tagged
      record
         checksum : Storage_Element;
      end record;

Dummy       : Dummy_Type;
Ptr_to_Data : Ptr_to_Data_Type;


I want Ptr_to_Data to point to some system address, say, 16#00E00000#
with unchecked conversion I could say,

function Convert_to_Pointer is new UNCHECKED_CONVERSION (
                                                  source => system.address,
                                                  target => Ptr_to_Data_Type);

Ptr_to_Data := Convert_to_Pointer(16#00E00000#);

I tried using System.Address_to_Access_Conversions,

package Convert_to_Pointer is new
         System.Address_to_Access_Conversions(system.address);

Data_Ptr : Convert_to_Pointer.Object_Pointer;

Data_Ptr := Convert_to_Pointer(16#00E00000#); --This is my problem!!
-- I need a type Ptr_to_Data_Type, NOT Convert_to_Pointer.Object_Pointer

I tried casting
Ptr_to_Data := Ptr_to_Data_Type(Data_Ptr); --It compiled..but when I ran it
SEGMENTATION FAULT ERROR showed up.
Can anybody suggest how do I get the correct access type to point to memory.

Thank you in advance.
Jay S.


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