1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- S Y S T E M . A T O M I C _ C O U N T E R S --
9 -- Copyright (C) 2011, AdaCore --
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. --
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. --
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/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 -- This implementation of the package for x86 processor. GCC can't generate
33 -- code for atomic builtins for 386 CPU. Only increment/decrement instructions
34 -- are supported, thus this implementaton uses machine code insertions to
35 -- access the necessary instructions.
37 with System.Machine_Code;
39 package body System.Atomic_Counters is
41 -- Add comments showing in normal asm language what we generate???
47 function Decrement (Item : in out Atomic_Counter) return Boolean is
51 System.Machine_Code.Asm
53 "lock%; decl" & ASCII.HT & "%0" & ASCII.LF & ASCII.HT
56 (Unsigned_32'Asm_Output ("=m", Item.Value),
57 Boolean'Asm_Output ("=qm", Aux)),
58 Inputs => Unsigned_32'Asm_Input ("m", Item.Value),
68 procedure Increment (Item : in out Atomic_Counter) is
70 System.Machine_Code.Asm
71 (Template => "lock%; incl" & ASCII.HT & "%0",
72 Outputs => Unsigned_32'Asm_Output ("=m", Item.Value),
73 Inputs => Unsigned_32'Asm_Input ("m", Item.Value),
81 function Is_One (Item : Atomic_Counter) return Boolean is
83 return Item.Value = 1;
86 end System.Atomic_Counters;