gcc/ada/s-taskin.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
   4 --                                                                          --
   5 --                        S Y S T E M . T A S K I N G                       --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2008, 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 2,  or (at your option) any later ver- --
  14 -- sion. GNARL 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.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNARL was developed by the GNARL team at Florida State University.       --
  30 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 pragma Polling (Off);
  35 --  Turn off polling, we do not want ATC polling to take place during tasking
  36 --  operations. It causes infinite loops and other problems.
  37
  38 with Ada.Unchecked_Deallocation;
  39
  40 with System.Task_Primitives.Operations;
  41 with System.Storage_Elements;
  42
  43 package body System.Tasking is
  44
  45    package STPO renames System.Task_Primitives.Operations;
  46
  47    ----------------------------
  48    -- Free_Entry_Names_Array --
  49    ----------------------------
  50
  51    procedure Free_Entry_Names_Array (Obj : in out Entry_Names_Array) is
  52       procedure Free_String is new
  53         Ada.Unchecked_Deallocation (String, String_Access);
  54    begin
  55       for Index in Obj'Range loop
  56          Free_String (Obj (Index));
  57       end loop;
  58    end Free_Entry_Names_Array;
  59
  60    ---------------------
  61    -- Detect_Blocking --
  62    ---------------------
  63
  64    function Detect_Blocking return Boolean is
  65       GL_Detect_Blocking : Integer;
  66       pragma Import (C, GL_Detect_Blocking, "__gl_detect_blocking");
  67       --  Global variable exported by the binder generated file.
  68       --  A value equal to 1 indicates that pragma Detect_Blocking is active,
  69       --  while 0 is used for the pragma not being present.
  70
  71    begin
  72       return GL_Detect_Blocking = 1;
  73    end Detect_Blocking;
  74
  75    ----------
  76    -- Self --
  77    ----------
  78
  79    function Self return Task_Id renames STPO.Self;
  80
  81    ------------------
  82    -- Storage_Size --
  83    ------------------
  84
  85    function Storage_Size (T : Task_Id) return System.Parameters.Size_Type is
  86    begin
  87       return
  88          System.Parameters.Size_Type
  89            (T.Common.Compiler_Data.Pri_Stack_Info.Size);
  90    end Storage_Size;
  91
  92    ---------------------
  93    -- Initialize_ATCB --
  94    ---------------------
  95
  96    procedure Initialize_ATCB
  97      (Self_ID          : Task_Id;
  98       Task_Entry_Point : Task_Procedure_Access;
  99       Task_Arg         : System.Address;
 100       Parent           : Task_Id;
 101       Elaborated       : Access_Boolean;
 102       Base_Priority    : System.Any_Priority;
 103       Task_Info        : System.Task_Info.Task_Info_Type;
 104       Stack_Size       : System.Parameters.Size_Type;
 105       T                : Task_Id;
 106       Success          : out Boolean) is
 107    begin
 108       T.Common.State := Unactivated;
 109
 110       --  Initialize T.Common.LL
 111
 112       STPO.Initialize_TCB (T, Success);
 113
 114       if not Success then
 115          return;
 116       end if;
 117
 118       T.Common.Parent := Parent;
 119       T.Common.Base_Priority := Base_Priority;
 120       T.Common.Current_Priority := 0;
 121       T.Common.Protected_Action_Nesting := 0;
 122       T.Common.Call := null;
 123       T.Common.Task_Arg := Task_Arg;
 124       T.Common.Task_Entry_Point := Task_Entry_Point;
 125       T.Common.Activator := Self_ID;
 126       T.Common.Wait_Count := 0;
 127       T.Common.Elaborated := Elaborated;
 128       T.Common.Activation_Failed := False;
 129       T.Common.Task_Info := Task_Info;
 130       T.Common.Global_Task_Lock_Nesting := 0;
 131       T.Common.Fall_Back_Handler := null;
 132       T.Common.Specific_Handler  := null;
 133
 134       if T.Common.Parent = null then
 135          --  For the environment task, the adjusted stack size is
 136          --  meaningless. For example, an unspecified Stack_Size means
 137          --  that the stack size is determined by the environment, or
 138          --  can grow dynamically. The Stack_Checking algorithm
 139          --  therefore needs to use the requested size, or 0 in
 140          --  case of an unknown size.
 141
 142          T.Common.Compiler_Data.Pri_Stack_Info.Size :=
 143             Storage_Elements.Storage_Offset (Stack_Size);
 144
 145       else
 146          T.Common.Compiler_Data.Pri_Stack_Info.Size :=
 147            Storage_Elements.Storage_Offset
 148              (Parameters.Adjust_Storage_Size (Stack_Size));
 149       end if;
 150
 151       --  Link the task into the list of all tasks
 152
 153       T.Common.All_Tasks_Link := All_Tasks_List;
 154       All_Tasks_List := T;
 155    end Initialize_ATCB;
 156
 157    ----------------
 158    -- Initialize --
 159    ----------------
 160
 161    Main_Task_Image : constant String := "main_task";
 162    --  Image of environment task
 163
 164    Main_Priority : Integer;
 165    pragma Import (C, Main_Priority, "__gl_main_priority");
 166    --  Priority for main task. Note that this is of type Integer, not
 167    --  Priority, because we use the value -1 to indicate the default
 168    --  main priority, and that is of course not in Priority'range.
 169
 170    Initialized : Boolean := False;
 171    --  Used to prevent multiple calls to Initialize
 172
 173    procedure Initialize is
 174       T             : Task_Id;
 175       Base_Priority : Any_Priority;
 176
 177       Success : Boolean;
 178       pragma Warnings (Off, Success);
 179
 180    begin
 181       if Initialized then
 182          return;
 183       end if;
 184
 185       Initialized := True;
 186
 187       --  Initialize Environment Task
 188
 189       if Main_Priority = Unspecified_Priority then
 190          Base_Priority := Default_Priority;
 191       else
 192          Base_Priority := Priority (Main_Priority);
 193       end if;
 194
 195       Success := True;
 196       T := STPO.New_ATCB (0);
 197       Initialize_ATCB
 198         (null, null, Null_Address, Null_Task, null, Base_Priority,
 199          Task_Info.Unspecified_Task_Info, 0, T, Success);
 200       pragma Assert (Success);
 201
 202       STPO.Initialize (T);
 203       STPO.Set_Priority (T, T.Common.Base_Priority);
 204       T.Common.State := Runnable;
 205       T.Common.Task_Image_Len := Main_Task_Image'Length;
 206       T.Common.Task_Image (Main_Task_Image'Range) := Main_Task_Image;
 207
 208       --  Only initialize the first element since others are not relevant
 209       --  in ravenscar mode. Rest of the initialization is done in Init_RTS.
 210
 211       T.Entry_Calls (1).Self := T;
 212    end Initialize;
 213
 214 end System.Tasking;