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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Teaching new tricks to an old dog (C++ -->Ada)
Newsgroups: comp.lang.ada,comp.lang.c++,comp.realtime,comp.software-eng
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Date: Tue, 8 Mar 2005 20:31:52 +0100
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Date: 2005-03-08T20:31:49+01:00
List-Id: <comp.lang.ada>

On Tue, 08 Mar 2005 13:33:33 -0500, CTips wrote:

> How easy is it to build an arena allocator in Ada?

It is trivial:

type Object is ...;
type Object_Ptr is access Object;
for Object_Ptr'Storage_Pool use My_Arena;

Here you are:

Ptr : Object_Ptr := new Object; -- This allocates it in My_Arena

Note that Object can still be allocated on the stack or in any other pool:

type Object_Universal_Ptr is access all Object;

This : Object;
            -- This allocates it on the stack
That : Object_Universal_Ptr := new Object;
            -- This will be in the(a) default pool (in the heap)

> Given a processor with load-word-locked and store-word-conditional, how 
> would I build an atomic increment function?

Why should I have atomic increment function? Ada has native concurrency
support. But if somebody would need that extremely low level thing as
atomic integers, then:

protected type Atomic_Integer is
   procedure Increment;
private
   Value : Integer;
end Atomic_Integer;

-- Implementation
protected body Atomic_Integer is
   procedure Increment is
   begin
      Value := Value + 1;
   end Increment;
end Atomic_Integer;

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de