gcc/ada/libgnarl/s-tpopsp__vxworks-tls.adb

   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) 1992-2018, 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
  36 separate (System.Task_Primitives.Operations)
  37 package 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
  99 end Specific;