1------------------------------------------------------------------------------
2--                                                                          --
3--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
4--                                                                          --
5--         SYSTEM.TASK_PRIMITIVES.OPERATIONS.REGISTER_FOREIGN_THREAD        --
6--                                                                          --
7--                                B o d y                                   --
8--                                                                          --
9--          Copyright (C) 2002-2011, 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
32with System.Task_Info;
33--  Use for Unspecified_Task_Info
34
35with System.Soft_Links;
36--  used to initialize TSD for a C thread, in function Self
37
38with System.Multiprocessors;
39
40separate (System.Task_Primitives.Operations)
41function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id is
42   Local_ATCB : aliased Ada_Task_Control_Block (0);
43   Self_Id    : Task_Id;
44   Succeeded  : Boolean;
45
46begin
47   --  This section is tricky. We must not call anything that might require
48   --  an ATCB, until the new ATCB is in place. In order to get an ATCB
49   --  immediately, we fake one, so that it is then possible to e.g allocate
50   --  memory (which might require accessing self).
51
52   --  Record this as the Task_Id for the thread
53
54   Local_ATCB.Common.LL.Thread := Thread;
55   Local_ATCB.Common.Current_Priority := System.Priority'First;
56   Specific.Set (Local_ATCB'Unchecked_Access);
57
58   --  It is now safe to use an allocator
59
60   Self_Id := new Ada_Task_Control_Block (0);
61
62   --  Finish initialization
63
64   Lock_RTS;
65   System.Tasking.Initialize_ATCB
66     (Self_Id, null, Null_Address, Null_Task,
67      Foreign_Task_Elaborated'Access,
68      System.Priority'First, System.Multiprocessors.Not_A_Specific_CPU, null,
69      Task_Info.Unspecified_Task_Info, 0, Self_Id, Succeeded);
70   Unlock_RTS;
71   pragma Assert (Succeeded);
72
73   Self_Id.Master_of_Task := 0;
74   Self_Id.Master_Within := Self_Id.Master_of_Task + 1;
75
76   for L in Self_Id.Entry_Calls'Range loop
77      Self_Id.Entry_Calls (L).Self := Self_Id;
78      Self_Id.Entry_Calls (L).Level := L;
79   end loop;
80
81   Self_Id.Common.State := Runnable;
82   Self_Id.Awake_Count := 1;
83
84   Self_Id.Common.Task_Image (1 .. 14) := "foreign thread";
85   Self_Id.Common.Task_Image_Len := 14;
86
87   --  Since this is not an ordinary Ada task, we will start out undeferred
88
89   Self_Id.Deferral_Level := 0;
90
91   --  We do not provide an alternate stack for foreign threads
92
93   Self_Id.Common.Task_Alternate_Stack := Null_Address;
94
95   System.Soft_Links.Create_TSD (Self_Id.Common.Compiler_Data);
96
97   --  ???
98   --  The following call is commented out to avoid dependence on the
99   --  System.Tasking.Initialization package. It seems that if we want
100   --  Ada.Task_Attributes to work correctly for C threads we will need to
101   --  raise the visibility of this soft link to System.Soft_Links. We are
102   --  putting that off until this new functionality is otherwise stable.
103
104   --  System.Tasking.Initialization.Initialize_Attributes_Link.all (T);
105
106   Enter_Task (Self_Id);
107
108   return Self_Id;
109end Register_Foreign_Thread;
110