1------------------------------------------------------------------------------
2--                                                                          --
3--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
4--                                                                          --
5--                SYSTEM.TASK_PRIMITIVES.OPERATIONS.SPECIFIC                --
6--                                                                          --
7--                                B o d y                                   --
8--                                                                          --
9--         Copyright (C) 1992-2011, Free Software Foundation, Inc.          --
10--                                                                          --
11-- GNARL is free software; you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- GNARL was developed by the GNARL team at Florida State University.       --
28-- Extensive contributions were provided by Ada Core Technologies, Inc.     --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  This is a version of this package using TLS and where foreign threads are
33--  recognized.
34
35separate (System.Task_Primitives.Operations)
36package body Specific is
37
38   ATCB : aliased Task_Id := null;
39   pragma Thread_Local_Storage (ATCB);
40
41   ----------------
42   -- Initialize --
43   ----------------
44
45   procedure Initialize (Environment_Task : Task_Id) is
46   begin
47      ATCB := Environment_Task;
48   end Initialize;
49
50   -------------------
51   -- Is_Valid_Task --
52   -------------------
53
54   function Is_Valid_Task return Boolean is
55   begin
56      return ATCB /= null;
57   end Is_Valid_Task;
58
59   ---------
60   -- Set --
61   ---------
62
63   procedure Set (Self_Id : Task_Id) is
64   begin
65      ATCB := Self_Id;
66   end Set;
67
68   ----------
69   -- Self --
70   ----------
71
72   --  To make Ada tasks and C threads interoperate better, we have added some
73   --  functionality to Self. Suppose a C main program (with threads) calls an
74   --  Ada procedure and the Ada procedure calls the tasking runtime system.
75   --  Eventually, a call will be made to self. Since the call is not coming
76   --  from an Ada task, there will be no corresponding ATCB.
77
78   --  What we do in Self is to catch references that do not come from
79   --  recognized Ada tasks, and create an ATCB for the calling thread.
80
81   --  The new ATCB will be "detached" from the normal Ada task master
82   --  hierarchy, much like the existing implicitly created signal-server
83   --  tasks.
84
85   function Self return Task_Id is
86      Result : constant Task_Id := ATCB;
87   begin
88      if Result /= null then
89         return Result;
90      else
91         --  If the value is Null then it is a non-Ada task
92
93         return Register_Foreign_Thread;
94      end if;
95   end Self;
96
97end Specific;
98