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
42package 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
92end System.Task_Info;
93