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From: "Michael Erdmann" <boavista@berlin.snafu.de>
Subject: Re: Q: How to do memory access with gnat
Date: 1997/07/22
Message-ID: <hagolyucxruwssd.pminews@n241-156.berlin.snafu.de>#1/1
X-Deja-AN: 258186402
References: <easwuowobrigfij.pminews@boavista.berlin.snafu.de>
Organization: Unlimited Surprise Systems, Berlin
Reply-To: "Michael Erdmann" <boavista@berlin.snafu.de>
Newsgroups: comp.lang.ada
Date: 1997-07-22T00:00:00+00:00
List-Id: <comp.lang.ada>


On Sun, 20 Jul 97 14:37:05, Michael Erdmann wrote:

:>Hi
:>
:>i like to do something like this in Ada95  (excuse the C-example):
:>
:>	typedef struct  {  ..,other_data;   char data[1];  }  Msg_data; 
:>	Msg_Data	*shared;
:>
:>	// get some memory from the system
:>	DosGetSharedMemory( ..., &shared... )
:>
:>	// copy data into shared memory 
:>	for( i ,,,, )
:>	   shared->data[i] := some_data[i];
:>
:>In  Ada95  i am not able to copy data from an Ada object into a some external
:>memory.
:>Any idea ?
:> 
:>
:>
If some body is interested how i managed to solve the Problem here is my
solution but i dont know if it works for all processor types:

with System;                    use System;
with System.Storage_Elements;   use System.Storage_Elements;
with System.Address_To_Access_Conversions;
with Unchecked_Conversion;


   function TO_Storage_Offset is new 
        Unchecked_Conversion(Source => Integer, Target=>Storage_Offset);

   package BYTE_Access is new System.Address_To_Access_Conversions( BYTE );

   procedure Store_Byte( base : Address ; offset : Integer ; value:BYTE ) is
   begin
      BYTE_Access.To_Pointer(base+TO_Storage_Offset(offset) ).all := value;
   end Store_Byte;

   function Get_Byte( base: Address; offset : Integer ) return BYTE is
   begin
      return BYTE_Access.To_Pointer(base+TO_Storage_Offset(offset)).all;
   end Get_Byte;