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) 1992-2021, Free Software Foundation, Inc.          --
10--                                                                          --
11-- GNAT 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 VxWorks version of this package using Thread_Local_Storage
33--  support (VxWorks 6.6 and higher). The implementation is based on __threads
34--  support.
35
36separate (System.Task_Primitives.Operations)
37package body Specific is
38
39   ATCB : aliased Task_Id := null;
40   --  Ada Task_Id associated with a thread
41   pragma Thread_Local_Storage (ATCB);
42
43   ----------------
44   -- Initialize --
45   ----------------
46
47   procedure Initialize is
48   begin
49      null;
50   end Initialize;
51
52   -------------------
53   -- Is_Valid_Task --
54   -------------------
55
56   function Is_Valid_Task return Boolean is
57   begin
58      return ATCB /= Null_Task;
59   end Is_Valid_Task;
60
61   ---------
62   -- Set --
63   ---------
64
65   procedure Set (Self_Id : Task_Id) is
66   begin
67      ATCB := Self_Id;
68   end Set;
69
70   ----------
71   -- Self --
72   ----------
73
74   --  To make Ada tasks and C threads interoperate better, we have added some
75   --  functionality to Self. Suppose a C main program (with threads) calls an
76   --  Ada procedure and the Ada procedure calls the tasking runtime system.
77   --  Eventually, a call will be made to self. Since the call is not coming
78   --  from an Ada task, there will be no corresponding ATCB.
79
80   --  What we do in Self is to catch references that do not come from
81   --  recognized Ada tasks, and create an ATCB for the calling thread.
82
83   --  The new ATCB will be "detached" from the normal Ada task master
84   --  hierarchy, much like the existing implicitly created signal-server
85   --  tasks.
86
87   function Self return Task_Id is
88      Result : constant Task_Id := ATCB;
89   begin
90      if Result /= null then
91         return Result;
92      else
93         --  If the value is Null then it is a non-Ada task
94
95         return Register_Foreign_Thread;
96      end if;
97   end Self;
98
99end Specific;
100