gcc/ada/s-tasinf.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                     S Y S T E M . T A S K _ I N F O                      --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                           (Compiler Interface)                           --
   9 --                                                                          --
  10 --          Copyright (C) 1992-2001 Free Software Foundation, Inc.          --
  11 --                                                                          --
  12 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNAT was originally developed  by the GNAT team at  New York University. --
  31 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This package contains the definitions and routines associated with the
  36 --  implementation of the Task_Info pragma. It is specialized appropriately
  37 --  for targets that make use of this pragma.
  38
  39 --  Note: the compiler generates direct calls to this interface, via Rtsfind.
  40 --  Any changes to this interface may require corresponding compiler changes.
  41
  42 with Unchecked_Deallocation;
  43 package System.Task_Info is
  44 pragma Elaborate_Body;
  45 --  To ensure that a body is allowed
  46
  47    -----------------------------------------
  48    -- Implementation of Task_Info Feature --
  49    -----------------------------------------
  50
  51    --  The Task_Info pragma:
  52
  53    --    pragma Task_Info (EXPRESSION);
  54
  55    --  allows the specification on a task by task basis of a value of type
  56    --  System.Task_Info.Task_Info_Type to be passed to a task when it is
  57    --  created. The specification of this type, and the effect on the task
  58    --  that is created is target dependent.
  59
  60    --  The Task_Info pragma appears within a task definition (compare the
  61    --  definition and implementation of pragma Priority). If no such pragma
  62    --  appears, then the value Task_Info_Unspecified is passed. If a pragma
  63    --  is present, then it supplies an alternative value. If the argument of
  64    --  the pragma is a discriminant reference, then the value can be set on
  65    --  a task by task basis by supplying the appropriate discriminant value.
  66
  67    --  Note that this means that the type used for Task_Info_Type must be
  68    --  suitable for use as a discriminant (i.e. a scalar or access type).
  69
  70    ------------------
  71    -- Declarations --
  72    ------------------
  73
  74    type Scope_Type is
  75      (Process_Scope,
  76       --  Contend only with threads in same process
  77
  78       System_Scope,
  79       --  Contend with all threads on same CPU
  80
  81       Default_Scope);
  82
  83    type Task_Info_Type is new Scope_Type;
  84    --  Type used for passing information to task create call, using the
  85    --  Task_Info pragma. This type may be specialized for individual
  86    --  implementations, but it must be a type that can be used as a
  87    --  discriminant (i.e. a scalar or access type).
  88
  89    type Task_Image_Type is access String;
  90    --  Used to generate a meaningful identifier for tasks that are variables
  91    --  and components of variables.
  92
  93    procedure Free_Task_Image is new
  94      Unchecked_Deallocation (String, Task_Image_Type);
  95
  96    Unspecified_Task_Info : constant Task_Info_Type := Default_Scope;
  97    --  Value passed to task in the absence of a Task_Info pragma
  98
  99 end System.Task_Info;