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

--                                                                          --

--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --

--                                                                          --

--                SYSTEM.TASK_PRIMITIVES.OPERATIONS.SPECIFIC                --

--                                                                          --

--                                B o d y                                   --

--                                                                          --

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

--                                                                          --

-- GNARL 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/>.                                          --

--                                                                          --

-- GNARL was developed by the GNARL team at Florida State University.       --

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

--                                                                          --

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

--  This is a POSIX version of this package where foreign threads are

--  recognized.

separate (System.Task_Primitives.Operations)

package body Specific is

   ATCB_Key : aliased pthread_key_t;

   --  Key used to find the Ada Task_Id associated with a thread

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

   -- Initialize --

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

   procedure Initialize (Environment_Task : Task_Id) is

      pragma Warnings (Off, Environment_Task);

      Result : Interfaces.C.int;

   begin

      Result := pthread_key_create (ATCB_Key'Access, null);

      pragma Assert (Result = 0);

   end Initialize;

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

   -- Is_Valid_Task --

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

   function Is_Valid_Task return Boolean is

   begin

      return pthread_getspecific (ATCB_Key) /= System.Null_Address;

   end Is_Valid_Task;

   ---------

   -- Set --

   ---------

   procedure Set (Self_Id : Task_Id) is

      Result : Interfaces.C.int;

   begin

      Result := pthread_setspecific (ATCB_Key, To_Address (Self_Id));

      pragma Assert (Result = 0);

   end Set;

   ----------

   -- Self --

   ----------

   --  To make Ada tasks and C threads interoperate better, we have added some

   --  functionality to Self. Suppose a C main program (with threads) calls an

   --  Ada procedure and the Ada procedure calls the tasking runtime system.

   --  Eventually, a call will be made to self. Since the call is not coming

   --  from an Ada task, there will be no corresponding ATCB.

   --  What we do in Self is to catch references that do not come from

   --  recognized Ada tasks, and create an ATCB for the calling thread.

   --  The new ATCB will be "detached" from the normal Ada task master

   --  hierarchy, much like the existing implicitly created signal-server

   --  tasks.

   function Self return Task_Id is

      Result : System.Address;

   begin

      Result := pthread_getspecific (ATCB_Key);

      --  If the key value is Null then it is a non-Ada task

      if Result /= System.Null_Address then

         return To_Task_Id (Result);

      else

         return Register_Foreign_Thread;

      end if;

   end Self;

end Specific;