+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNAT RUN-TIME COMPONENTS --
--- --
--- S Y S T E M . A T O M I C _ C O U N T E R S --
--- --
--- B o d y --
--- --
--- Copyright (C) 2011-2021, 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 implementation of the package for x86 processor. GCC can't generate
--- code for atomic builtins for 386 CPU. Only increment/decrement instructions
--- are supported, thus this implementaton uses machine code insertions to
--- access the necessary instructions.
-
-with System.Machine_Code;
-
-package body System.Atomic_Counters is
-
- -- Add comments showing in normal asm language what we generate???
-
- ---------------
- -- Decrement --
- ---------------
-
- function Decrement (Item : aliased in out Atomic_Unsigned) return Boolean is
- Aux : Boolean;
-
- begin
- System.Machine_Code.Asm
- (Template =>
- "lock%; decl" & ASCII.HT & "%0" & ASCII.LF & ASCII.HT
- & "sete %1",
- Outputs =>
- (Atomic_Unsigned'Asm_Output ("=m", Item),
- Boolean'Asm_Output ("=qm", Aux)),
- Inputs => Atomic_Unsigned'Asm_Input ("m", Item),
- Volatile => True);
-
- return Aux;
- end Decrement;
-
- procedure Decrement (Item : aliased in out Atomic_Unsigned) is
- begin
- if Decrement (Item) then
- null;
- end if;
- end Decrement;
-
- function Decrement (Item : in out Atomic_Counter) return Boolean is
- begin
- return Decrement (Item.Value);
- end Decrement;
-
- ---------------
- -- Increment --
- ---------------
-
- procedure Increment (Item : aliased in out Atomic_Unsigned) is
- begin
- System.Machine_Code.Asm
- (Template => "lock%; incl" & ASCII.HT & "%0",
- Outputs => Atomic_Unsigned'Asm_Output ("=m", Item),
- Inputs => Atomic_Unsigned'Asm_Input ("m", Item),
- Volatile => True);
- end Increment;
-
- procedure Increment (Item : in out Atomic_Counter) is
- begin
- Increment (Item.Value);
- end Increment;
-
- ----------------
- -- Initialize --
- ----------------
-
- procedure Initialize (Item : out Atomic_Counter) is
- begin
- Item.Value := 1;
- end Initialize;
-
- ------------
- -- Is_One --
- ------------
-
- function Is_One (Item : Atomic_Counter) return Boolean is
- begin
- return Item.Value = 1;
- end Is_One;
-
-end System.Atomic_Counters;