Re: Problems with Ada.Real_Time on GNAT?

["David C. Hoos" <david.c.hoos.sr@ada95.com>]

----- Original Message -----
From: "Florian Weimer" <fw@deneb.enyo.de>
Newsgroups: comp.lang.ada
To: <comp.lang.ada@ada.eu.org>
Sent: Thursday, May 16, 2002 3:18 PM
Subject: Re: Problems with Ada.Real_Time on GNAT?


> file13@qlippoth.zzn.com (file13) writes:
>
> > http://www.qlippoth.com/shuffle.adb
> >
> > It works fine under Windows 2000 but on Linux under both 3.13 and 3.14
> > I (and the guy who is testing all the programs) keep getting
> > segmentation faults when run.
>
> You are hitting the 2 MB stack size limit.  You should allocate the
> large array using an allocator.

With all due respect, I submit that the problem is _not_ the stack limit,
but, rather the fact that to use the real-time annex, one must compile and
link
with the FSU threads run-time, instead of the Linux-native threads run-time.

One disadvantage of running under the FSU run-time, is that processes must
run with root privileges -- e.g., by means of setuid permissions and root
ownership of the executable.

Instead, I chose to use the facilities of Ada.Calendar, and I also took the
liberty
of showing a better way to define the types, and cleaning up the output by
limiting the number of values on a line to ten.

Here is the modified code -- it should run correctly under either run-time:

with Ada.Calendar;
with Ada.Numerics.Discrete_Random;
with Ada.Text_IO;
procedure Shuffle is

   subtype Index is Integer range 1 .. 1000000;

   --  Regular vars
   List   : array (Index) of Integer;
   X, Tmp : Integer;

   --  Timing stuff
   Start  : Ada.Calendar.Time;
   Finish : Ada.Calendar.Time;

   --  Random integer stuff
   package Rand is new Ada.Numerics.Discrete_Random (Index);
   Seed : Rand.Generator;
   use type Ada.Calendar.Time;
begin

   Rand.Reset (Seed);

   --  Populate List
   Ada.Text_IO.Put_Line
     ("Populating collection list...");
   for I in List'Range loop
      List (I) := I;
   end loop;

   --  Shuffle
   Ada.Text_IO.Put_Line
     ("Randomizing collection list.  Starting timer:");
   Start := Ada.Calendar.Clock;

   for I in List'Range loop
      X := Rand.Random (Seed);
      Tmp := List (I);
      List (I) := List (X);
      List (X) := Tmp;
   end loop;

   Finish := Ada.Calendar.Clock;
   Ada.Text_IO.New_Line;
   Ada.Text_IO.Put_Line
     ("Time to shuffle in seconds:" & Duration'Image (Finish - Start));

   --  Print 1st 100 of List
   Ada.Text_IO.New_Line;
   for I in 1 .. 100 loop
      Ada.Text_IO.Put (Integer'Image (List (I)));
      if I mod 10 = 0 then
         Ada.Text_IO.New_Line;
      end if;
   end loop;

end Shuffle;