--     The Ada Structured Library - A set of container classes and general
--     tools for use with Ada95.
--     Copyright (C) 1998  Corey Minyard (minyard@acm.org)
--
--     This library is free software; you can redistribute it and/or
--     modify it under the terms of the GNU Library General Public
--     License as published by the Free Software Foundation; either
--     version 2 of the License, or (at your option) any later version.
--
--     This library is distributed in the hope that it will be useful,
--     but WITHOUT ANY WARRANTY; without even the implied warranty of
--     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
--     Library General Public License for more details.
--
--     You should have received a copy of the GNU Library General Public
--     License along with this library; if not, write to the Free
--     Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
--     MA 02111-1307, USA
--

-- A standard binary semaphore.  Note that giving an untaken semaphore is
-- legal but has no effect.  This can be used as a waiting semphore by
-- taking it once (to claim it) then using Take to wait.  Then Give will
-- wake up the waiting task.

package Asl.Semaphore.Binary is

   type Object is new Asl.Semaphore.Object with private;
   type Object_Ptr is access all Object;

   -- Claim the semaphore.  Will block until the semaphore is available.
   procedure Take (O : in out Object);

   -- Release the semaphore.
   procedure Give (O : in out Object);

   -- Try to take the semaphore, but return an error if not successful.
   -- Returns True if the semaphore was claimed and False if not.  This
   -- will wait up to Timeout time for the semaphore to become available.
   procedure Try_To_Take (O       : in out Object;
                          Success : out Boolean;
                          Timeout : in Duration := 0.0);

private

   protected type Mutex is
      entry Wait;
      procedure Release;
   private
      Claimed : Boolean := False;
   end Mutex;

   type Object is new Asl.Semaphore.Object with record
      The_Mutex : Mutex;
   end record;

end Asl.Semaphore.Binary;