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 --                                                                          --
   9 --          Copyright (C) 1992-2009, 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 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This package contains the definitions and routines associated with the
  33 --  implementation and use of the Task_Info pragma. It is specialized
  34 --  appropriately for targets that make use of this pragma.
  35
  36 --  Note: the compiler generates direct calls to this interface, via Rtsfind.
  37 --  Any changes to this interface may require corresponding compiler changes.
  38
  39 --  This unit may be used directly from an application program by providing
  40 --  an appropriate WITH, and the interface can be expected to remain stable.
  41
  42 package System.Task_Info is
  43    pragma Preelaborate;
  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 Unspecified_Task_Info 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    Unspecified_Task_Info : constant Task_Info_Type := Default_Scope;
  90    --  Value passed to task in the absence of a Task_Info pragma
  91
  92 end System.Task_Info;