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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
References: <3A9CD67C.9B15C417@linuxchip.demon.co.uk>
Subject: Re: Problems with large records (GNAT) [continued]
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Date: Fri, 2 Mar 2001 14:32:42 -0600
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Date: 2001-03-02T14:32:42-06:00
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Dr Adrian Wrigley wrote in message
<3A9CD67C.9B15C417@linuxchip.demon.co.uk>...
>Hi all!
>
>You might remember a while back I had a problem with 'Size failing
>on large types, using GNAT (3.12p Intel Linux (Red Hat 6.2)).
>I never managed to solve that problem, and made do with keeping
>all my records under 256MB (!).


I tried this for grins on Janus/Ada. I get

** Unhandled CONSTRAINT_ERROR
   Value of literal out of the base type

which makes sense, because Janus/Ada only has 32-bit integers.
Moreover, it won't work right, because Big_T has a dynamic size. How
compilers allocate that will vary, but it doesn't necessarily have to be
continugous. (Indeed, Item_T'Size = 32*8 on Janus/Ada; the
array is stored separately.)

So, I tried using "new" instead, with the index type of Big_T being
static. Here's the result:

First is  3.14159E+00 last is  2.71828E+00

Sounds to me like you need a different compiler.  Our phone number is
1-800-722-3248 or visit www.rrsoftware.com. :-)

(I would not expect a problem with a program like this in Janus/Ada,
since it does all of its memory address calculations in units of bytes.
But then again, I won't expect it in any other compiler either.)

                Randy Brukardt.

-- Here's the program I ran:

with Text_IO;
procedure Dum2 is

   Size : constant := 256*1024*1024 - 1;
   type Index_Type is range 1 .. Size;
   type Big_T is array (Index_Type) of Float;

   type Item_T is record
      First : Float;
      Item  : Big_T;
      Last  : Float;
   end record;

   type Item_A is access all Item_T;

   X : Item_A;

begin

   X := new Item_T;

   X.First := 3.14159;
   X.Last  := 2.71828;

   Text_IO.Put_Line ("First is " & Float'Image (X.First) &
                     " last is " & Float'Image (X.Last));

end Dum2;