blob: 55d6bf0ece83772f4993aa05a1efe8b8a5851005 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
|
------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- S Y S T E M . A T O M I C _ C O U N T E R S --
-- --
-- S p e c --
-- --
-- Copyright (C) 2011-2013, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This package provides atomic counter on platforms where it is supported:
-- - all Alpha platforms
-- - all ia64 platforms
-- - all PowerPC platforms
-- - all SPARC V9 platforms
-- - all x86 platforms
-- - all x86_64 platforms
-- Why isn't this package available to application programs???
package System.Atomic_Counters is
pragma Preelaborate;
type Atomic_Counter is limited private;
-- Type for atomic counter objects. Note, initial value of the counter is
-- one. This allows using an atomic counter as member of record types when
-- object of these types are created at library level in preelaborable
-- compilation units.
--
-- Atomic_Counter is declared as private limited type to provide highest
-- level of protection from unexpected use. All available operations are
-- declared below, and this set should be as small as possible.
procedure Increment (Item : in out Atomic_Counter);
pragma Inline_Always (Increment);
-- Increments value of atomic counter.
function Decrement (Item : in out Atomic_Counter) return Boolean;
pragma Inline_Always (Decrement);
-- Decrements value of atomic counter, returns True when value reach zero.
function Is_One (Item : Atomic_Counter) return Boolean;
pragma Inline_Always (Is_One);
-- Returns True when value of the atomic counter is one.
procedure Initialize (Item : out Atomic_Counter);
pragma Inline_Always (Initialize);
-- Initialize counter by setting its value to one. This subprogram is
-- intended to be used in special cases when counter object can't be
-- initialized in standard way.
private
type Unsigned_32 is mod 2 ** 32;
type Atomic_Counter is limited record
Value : aliased Unsigned_32 := 1;
pragma Atomic (Value);
end record;
end System.Atomic_Counters;
|
