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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT RUN-TIME COMPONENTS                         --

--                                                                          --

--             A D A . S Y N C H R O N O U S _ B A R R I E R S              --

--                                                                          --

--                                  B o d y                                 --

--                                                                          --

--          Copyright (C) 1992-2011, Free Software Foundation, Inc.         --

--                                                                          --

-- This specification is derived from the Ada Reference Manual for use with --

-- GNAT. The copyright notice above, and the license provisions that follow --

-- apply solely to the  contents of the part following the private keyword. --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

--  This is the body of this package using POSIX barriers

with Interfaces.C; use Interfaces.C;

package body Ada.Synchronous_Barriers is

   --------------------

   -- POSIX barriers --

   --------------------

   function pthread_barrier_init

     (barrier : not null access pthread_barrier_t;

      attr    : System.Address := System.Null_Address;

      count   : unsigned) return int;

   pragma Import (C, pthread_barrier_init, "pthread_barrier_init");

   --  Initialize barrier with the attributes in attr. The barrier is opened

   --  when count waiters arrived. If attr is null the default barrier

   --  attributes shall be used.

   function pthread_barrier_destroy

     (barrier : not null access pthread_barrier_t) return int;

   pragma Import (C, pthread_barrier_destroy, "pthread_barrier_destroy");

   --  Destroy a previously dynamically initialized barrier

   function pthread_barrier_wait

     (barrier : not null access pthread_barrier_t) return int;

   pragma Import (C, pthread_barrier_wait, "pthread_barrier_wait");

   --  Wait on barrier

   --------------

   -- Finalize --

   --------------

   overriding procedure Finalize (Barrier : in out Synchronous_Barrier) is

      Result : int;

   begin

      Result := pthread_barrier_destroy (Barrier.POSIX_Barrier'Access);

      pragma Assert (Result = 0);

   end Finalize;

   overriding procedure Initialize (Barrier : in out Synchronous_Barrier) is

      Result : int;

   begin

      Result := pthread_barrier_init

        (barrier => Barrier.POSIX_Barrier'Access,

         attr    => System.Null_Address,

         count   => unsigned (Barrier.Release_Threshold));

      pragma Assert (Result = 0);

   end Initialize;

   ----------------------

   -- Wait_For_Release --

   ----------------------

   procedure Wait_For_Release

     (The_Barrier : in out Synchronous_Barrier;

      Notified    : out Boolean)

   is

      Result : int;

      PTHREAD_BARRIER_SERIAL_THREAD : constant := -1;

      --  Value used to indicate the task which receives the notification for

      --  the barrier open.

   begin

      Result := pthread_barrier_wait

        (barrier => The_Barrier.POSIX_Barrier'Access);

      pragma Assert

        (Result = 0 or else Result = PTHREAD_BARRIER_SERIAL_THREAD);

      Notified := (Result = PTHREAD_BARRIER_SERIAL_THREAD);

   end Wait_For_Release;

end Ada.Synchronous_Barriers;