1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT RUN-TIME COMPONENTS                         --
4--                                                                          --
5--               S Y S T E M . A T O M I C _ C O U N T E R S                --
6--                                                                          --
7--                                 B o d y                                  --
8--                                                                          --
9--          Copyright (C) 2011-2015, 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 is version of the package, for use on platforms where this capability
33--  is not supported. All Atomic_Counter operations raises Program_Error,
34--  Atomic_Unsigned operations processed in non-atomic manner.
35
36package body System.Atomic_Counters is
37
38   ---------------
39   -- Decrement --
40   ---------------
41
42   function Decrement (Item : in out Atomic_Counter) return Boolean is
43   begin
44      raise Program_Error;
45      return False;
46   end Decrement;
47
48   function Decrement (Item : aliased in out Atomic_Unsigned) return Boolean is
49   begin
50      --  Could not use Item := Item - 1; because it is disabled in spec.
51      Item := Atomic_Unsigned'Pred (Item);
52      return Item = 0;
53   end Decrement;
54
55   procedure Decrement (Item : aliased in out Atomic_Unsigned) is
56   begin
57      Item := Atomic_Unsigned'Pred (Item);
58   end Decrement;
59
60   ---------------
61   -- Increment --
62   ---------------
63
64   procedure Increment (Item : in out Atomic_Counter) is
65   begin
66      raise Program_Error;
67   end Increment;
68
69   procedure Increment (Item : aliased in out Atomic_Unsigned) is
70   begin
71      Item := Atomic_Unsigned'Succ (Item);
72   end Increment;
73
74   ----------------
75   -- Initialize --
76   ----------------
77
78   procedure Initialize (Item : out Atomic_Counter) is
79   begin
80      raise Program_Error;
81   end Initialize;
82
83   ------------
84   -- Is_One --
85   ------------
86
87   function Is_One (Item : Atomic_Counter) return Boolean is
88   begin
89      raise Program_Error;
90      return False;
91   end Is_One;
92
93end System.Atomic_Counters;
94