gcc/ada/libgnarl/s-tpopsp__vxworks-rtp.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) 1992-2020, 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 for RTPs where foreign threads
  33 --  are recognized. The implementation is based on VxWorks tlsLib or oldTlsLib.
  34
  35 separate (System.Task_Primitives.Operations)
  36 package body Specific is
  37
  38    ATCB_Key : int := 0;
  39    --  Key used to find the Ada Task_Id associated with a thread
  40
  41    ----------------
  42    -- Initialize --
  43    ----------------
  44
  45    procedure Initialize is
  46    begin
  47       ATCB_Key := tlsKeyCreate;
  48       pragma Assert (ATCB_Key /= ERROR);
  49    end Initialize;
  50
  51    -------------------
  52    -- Is_Valid_Task --
  53    -------------------
  54
  55    function Is_Valid_Task return Boolean is
  56    begin
  57       return tlsValueGet (ATCB_Key) /= System.Null_Address;
  58    end Is_Valid_Task;
  59
  60    ---------
  61    -- Set --
  62    ---------
  63
  64    procedure Set (Self_Id : Task_Id) is
  65       Result : STATUS;
  66    begin
  67       Result := tlsValueSet (ATCB_Key, To_Address (Self_Id));
  68       pragma Assert (Result /= ERROR);
  69    end Set;
  70
  71    ----------
  72    -- Self --
  73    ----------
  74
  75    --  To make Ada tasks and C threads interoperate better, we have added some
  76    --  functionality to Self. Suppose a C main program (with threads) calls an
  77    --  Ada procedure and the Ada procedure calls the tasking runtime system.
  78    --  Eventually, a call will be made to self. Since the call is not coming
  79    --  from an Ada task, there will be no corresponding ATCB.
  80
  81    --  What we do in Self is to catch references that do not come from
  82    --  recognized Ada tasks, and create an ATCB for the calling thread.
  83
  84    --  The new ATCB will be "detached" from the normal Ada task master
  85    --  hierarchy, much like the existing implicitly created signal-server
  86    --  tasks.
  87
  88    function Self return Task_Id is
  89       Result : constant Task_Id := To_Task_Id (tlsValueGet (ATCB_Key));
  90    begin
  91       if Result /= null then
  92          return Result;
  93       else
  94          --  If the value is Null then it is a non-Ada task
  95
  96          return Register_Foreign_Thread;
  97       end if;
  98    end Self;
  99
 100 end Specific;