1------------------------------------------------------------------------------
2--                                                                          --
3--                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
4--                                                                          --
5--    S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S .   --
6--                              S P E C I F I C                             --
7--                                                                          --
8--                                  B o d y                                 --
9--                                                                          --
10--                             $Revision: 1.2 $
11--                                                                          --
12--            Copyright (C) 1991-2003, Florida State University             --
13--            Copyright (C) 2008-2012, Free Software Foundation, Inc.       --
14--                                                                          --
15-- GNARL is free software; you can  redistribute it  and/or modify it under --
16-- terms of the  GNU General Public License as published  by the Free Soft- --
17-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
18-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
19-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
20-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
21--                                                                          --
22-- As a special exception under Section 7 of GPL version 3, you are granted --
23-- additional permissions described in the GCC Runtime Library Exception,   --
24-- version 3.1, as published by the Free Software Foundation.               --
25--                                                                          --
26-- You should have received a copy of the GNU General Public License and    --
27-- a copy of the GCC Runtime Library Exception along with this program;     --
28-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
29-- <http://www.gnu.org/licenses/>.                                          --
30--                                                                          --
31-- GNARL was developed by the GNARL team at Florida State University. It is --
32-- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
33-- State University (http://www.gnat.com).                                  --
34--                                                                          --
35------------------------------------------------------------------------------
36
37--  This is a RTEMS version of this package which uses a special
38--  variable for Ada self which is context switched implicitly by RTEMS.
39--
40--  This is the same as the POSIX version except that an RTEMS variable
41--  is used instead of a POSIX key.
42
43separate (System.Task_Primitives.Operations)
44package body Specific is
45
46   --  The following gives the Ada run-time direct access to a variable
47   --  context switched by RTEMS at the lowest level.
48
49   ATCB_Key : System.Address;
50   pragma Import (C, ATCB_Key, "rtems_ada_self");
51
52   ----------------
53   -- Initialize --
54   ----------------
55
56   procedure Initialize (Environment_Task : Task_Id) is
57      pragma Warnings (Off, Environment_Task);
58
59   begin
60      ATCB_Key := To_Address (Environment_Task);
61   end Initialize;
62
63   -------------------
64   -- Is_Valid_Task --
65   -------------------
66
67   function Is_Valid_Task return Boolean is
68   begin
69      return ATCB_Key /= System.Null_Address;
70   end Is_Valid_Task;
71
72   ---------
73   -- Set --
74   ---------
75
76   procedure Set (Self_Id : Task_Id) is
77   begin
78      ATCB_Key := To_Address (Self_Id);
79   end Set;
80
81   ----------
82   -- Self --
83   ----------
84
85   --  To make Ada tasks and C threads interoperate better, we have added some
86   --  functionality to Self. Suppose a C main program (with threads) calls an
87   --  Ada procedure and the Ada procedure calls the tasking runtime system.
88   --  Eventually, a call will be made to self. Since the call is not coming
89   --  from an Ada task, there will be no corresponding ATCB.
90
91   --  What we do in Self is to catch references that do not come from
92   --  recognized Ada tasks, and create an ATCB for the calling thread.
93
94   --  The new ATCB will be "detached" from the normal Ada task master
95   --  hierarchy, much like the existing implicitly created signal-server
96   --  tasks.
97
98   function Self return Task_Id is
99      Result : System.Address;
100
101   begin
102      Result := ATCB_Key;
103
104      --  If the key value is Null, then it is a non-Ada task.
105
106      if Result /= System.Null_Address then
107         return To_Task_Id (Result);
108      else
109         return Register_Foreign_Thread;
110      end if;
111   end Self;
112
113end Specific;
114