113 lines
4.4 KiB
Ada
113 lines
4.4 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- S Y S T E M . A T O M I C _ C O U N T E R S --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 2011-2015, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This implementation of the package for x86 processor. GCC can't generate
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-- code for atomic builtins for 386 CPU. Only increment/decrement instructions
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-- are supported, thus this implementaton uses machine code insertions to
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-- access the necessary instructions.
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with System.Machine_Code;
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package body System.Atomic_Counters is
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-- Add comments showing in normal asm language what we generate???
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---------------
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-- Decrement --
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---------------
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function Decrement (Item : aliased in out Atomic_Unsigned) return Boolean is
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Aux : Boolean;
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begin
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System.Machine_Code.Asm
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(Template =>
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"lock%; decl" & ASCII.HT & "%0" & ASCII.LF & ASCII.HT
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& "sete %1",
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Outputs =>
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(Atomic_Unsigned'Asm_Output ("=m", Item),
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Boolean'Asm_Output ("=qm", Aux)),
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Inputs => Atomic_Unsigned'Asm_Input ("m", Item),
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Volatile => True);
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return Aux;
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end Decrement;
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procedure Decrement (Item : aliased in out Atomic_Unsigned) is
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begin
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if Decrement (Item) then
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null;
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end if;
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end Decrement;
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function Decrement (Item : in out Atomic_Counter) return Boolean is
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begin
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return Decrement (Item.Value);
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end Decrement;
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---------------
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-- Increment --
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---------------
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procedure Increment (Item : aliased in out Atomic_Unsigned) is
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begin
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System.Machine_Code.Asm
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(Template => "lock%; incl" & ASCII.HT & "%0",
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Outputs => Atomic_Unsigned'Asm_Output ("=m", Item),
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Inputs => Atomic_Unsigned'Asm_Input ("m", Item),
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Volatile => True);
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end Increment;
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procedure Increment (Item : in out Atomic_Counter) is
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begin
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Increment (Item.Value);
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end Increment;
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----------------
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-- Initialize --
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----------------
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procedure Initialize (Item : out Atomic_Counter) is
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begin
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Item.Value := 1;
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end Initialize;
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------------
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-- Is_One --
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------------
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function Is_One (Item : Atomic_Counter) return Boolean is
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begin
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return Item.Value = 1;
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end Is_One;
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end System.Atomic_Counters;
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