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

--                                                                          --

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

--                                                                          --

--         SYSTEM.TASK_PRIMITIVES.OPERATIONS.REGISTER_FOREIGN_THREAD        --

--                                                                          --

--                                B o d y                                   --

--                                                                          --

--          Copyright (C) 2002-2011, 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.     --

--                                                                          --

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

with System.Task_Info;

--  Use for Unspecified_Task_Info

with System.Soft_Links;

--  used to initialize TSD for a C thread, in function Self

with System.Multiprocessors;

separate (System.Task_Primitives.Operations)

function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id is

   Local_ATCB : aliased Ada_Task_Control_Block (0);

   Self_Id    : Task_Id;

   Succeeded  : Boolean;

begin

   --  This section is tricky. We must not call anything that might require

   --  an ATCB, until the new ATCB is in place. In order to get an ATCB

   --  immediately, we fake one, so that it is then possible to e.g allocate

   --  memory (which might require accessing self).

   --  Record this as the Task_Id for the thread

   Local_ATCB.Common.LL.Thread := Thread;

   Local_ATCB.Common.Current_Priority := System.Priority'First;

   Specific.Set (Local_ATCB'Unchecked_Access);

   --  It is now safe to use an allocator

   Self_Id := new Ada_Task_Control_Block (0);

   --  Finish initialization

   Lock_RTS;

   System.Tasking.Initialize_ATCB

     (Self_Id, null, Null_Address, Null_Task,

      Foreign_Task_Elaborated'Access,

      System.Priority'First, System.Multiprocessors.Not_A_Specific_CPU, null,

      Task_Info.Unspecified_Task_Info, 0, Self_Id, Succeeded);

   Unlock_RTS;

   pragma Assert (Succeeded);

   Self_Id.Master_of_Task := 0;

   Self_Id.Master_Within := Self_Id.Master_of_Task + 1;

   for L in Self_Id.Entry_Calls'Range loop

      Self_Id.Entry_Calls (L).Self := Self_Id;

      Self_Id.Entry_Calls (L).Level := L;

   end loop;

   Self_Id.Common.State := Runnable;

   Self_Id.Awake_Count := 1;

   Self_Id.Common.Task_Image (1 .. 14) := "foreign thread";

   Self_Id.Common.Task_Image_Len := 14;

   --  Since this is not an ordinary Ada task, we will start out undeferred

   Self_Id.Deferral_Level := 0;

   --  We do not provide an alternate stack for foreign threads

   Self_Id.Common.Task_Alternate_Stack := Null_Address;

   System.Soft_Links.Create_TSD (Self_Id.Common.Compiler_Data);

   --  ???

   --  The following call is commented out to avoid dependence on the

   --  System.Tasking.Initialization package. It seems that if we want

   --  Ada.Task_Attributes to work correctly for C threads we will need to

   --  raise the visibility of this soft link to System.Soft_Links. We are

   --  putting that off until this new functionality is otherwise stable.

   --  System.Tasking.Initialization.Initialize_Attributes_Link.all (T);

   Enter_Task (Self_Id);

   return Self_Id;

end Register_Foreign_Thread;