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) 1992-2020, 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 VxWorks version of this package where foreign threads are
33--  recognized. The implementation is based on VxWorks taskVarLib.
34
35separate (System.Task_Primitives.Operations)
36package body Specific is
37
38   ATCB_Key : aliased System.Address := System.Null_Address;
39   --  Key used to find the Ada Task_Id associated with a thread
40
41   ATCB_Key_Addr : System.Address := ATCB_Key'Address;
42   pragma Export (Ada, ATCB_Key_Addr, "__gnat_ATCB_key_addr");
43   --  Exported to support the temporary AE653 task registration
44   --  implementation. This mechanism is used to minimize impact on other
45   --  targets.
46
47   Stack_Limit : aliased System.Address;
48
49   pragma Import (C, Stack_Limit, "__gnat_stack_limit");
50
51   type Set_Stack_Limit_Proc_Acc is access procedure;
52   pragma Convention (C, Set_Stack_Limit_Proc_Acc);
53
54   Set_Stack_Limit_Hook : Set_Stack_Limit_Proc_Acc;
55   pragma Import (C, Set_Stack_Limit_Hook, "__gnat_set_stack_limit_hook");
56   --  Procedure to be called when a task is created to set stack limit if
57   --  limit checking is used.
58
59   ----------------
60   -- Initialize --
61   ----------------
62
63   procedure Initialize is
64   begin
65      null;
66   end Initialize;
67
68   -------------------
69   -- Is_Valid_Task --
70   -------------------
71
72   function Is_Valid_Task return Boolean is
73   begin
74      return taskVarGet (taskIdSelf, ATCB_Key'Access) /= ERROR;
75   end Is_Valid_Task;
76
77   ---------
78   -- Set --
79   ---------
80
81   procedure Set (Self_Id : Task_Id) is
82      Result : STATUS;
83
84   begin
85      --  If argument is null, destroy task specific data, to make API
86      --  consistent with other platforms, and thus compatible with the
87      --  shared version of s-tpoaal.adb.
88
89      if Self_Id = null then
90         Result := taskVarDelete (taskIdSelf, ATCB_Key'Access);
91         pragma Assert (Result /= ERROR);
92         return;
93      end if;
94
95      if not Is_Valid_Task then
96         Result := taskVarAdd (Self_Id.Common.LL.Thread, ATCB_Key'Access);
97         pragma Assert (Result = OK);
98
99         if Stack_Check_Limits
100           and then Result /= ERROR
101           and then Set_Stack_Limit_Hook /= null
102         then
103            --  This will be initialized from taskInfoGet() once the task is
104            --  is running.
105
106            Result :=
107              taskVarAdd (Self_Id.Common.LL.Thread, Stack_Limit'Access);
108            pragma Assert (Result /= ERROR);
109         end if;
110      end if;
111
112      Result :=
113        taskVarSet
114          (Self_Id.Common.LL.Thread,
115           ATCB_Key'Access,
116           To_Address (Self_Id));
117      pragma Assert (Result /= ERROR);
118   end Set;
119
120   ----------
121   -- Self --
122   ----------
123
124   --  To make Ada tasks and C threads interoperate better, we have added some
125   --  functionality to Self. Suppose a C main program (with threads) calls an
126   --  Ada procedure and the Ada procedure calls the tasking runtime system.
127   --  Eventually, a call will be made to self. Since the call is not coming
128   --  from an Ada task, there will be no corresponding ATCB.
129
130   --  What we do in Self is to catch references that do not come from
131   --  recognized Ada tasks, and create an ATCB for the calling thread.
132
133   --  The new ATCB will be "detached" from the normal Ada task master
134   --  hierarchy, much like the existing implicitly created signal-server
135   --  tasks.
136
137   function Self return Task_Id is
138      Result : constant Task_Id := To_Task_Id (ATCB_Key);
139   begin
140      if Result /= null then
141         return Result;
142      else
143         --  If the value is Null then it is a non-Ada task
144
145         return Register_Foreign_Thread;
146      end if;
147   end Self;
148
149end Specific;
150