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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- System.Atomic_Operations.Exchange --
-- --
-- B o d y --
-- --
-- Copyright (C) 2019-2023, 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. --
-- --
------------------------------------------------------------------------------
with System.Atomic_Primitives; use System.Atomic_Primitives;
with Interfaces.C;
package body System.Atomic_Operations.Exchange is
---------------------
-- Atomic_Exchange --
---------------------
function Atomic_Exchange
(Item : aliased in out Atomic_Type;
Value : Atomic_Type) return Atomic_Type
is
pragma Warnings (Off);
function Atomic_Exchange
(Ptr : System.Address;
Val : Atomic_Type;
Model : Mem_Model := Seq_Cst) return Atomic_Type;
pragma Import (Intrinsic, Atomic_Exchange, "__atomic_exchange_n");
pragma Warnings (On);
begin
if Atomic_Type'Object_Size in 8 | 16 | 32 | 64 then
return Atomic_Exchange (Item'Address, Value);
else
raise Program_Error;
end if;
end Atomic_Exchange;
---------------------------------
-- Atomic_Compare_And_Exchange --
---------------------------------
function Atomic_Compare_And_Exchange
(Item : aliased in out Atomic_Type;
Prior : aliased in out Atomic_Type;
Desired : Atomic_Type) return Boolean
is
pragma Warnings (Off);
function Atomic_Compare_Exchange
(Ptr : System.Address;
Expected : System.Address;
Desired : Atomic_Type;
Weak : Boolean := False;
Success_Model : Mem_Model := Seq_Cst;
Failure_Model : Mem_Model := Seq_Cst) return Boolean;
pragma Import
(Intrinsic, Atomic_Compare_Exchange, "__atomic_compare_exchange_n");
pragma Warnings (On);
begin
if Atomic_Type'Object_Size in 8 | 16 | 32 | 64 then
return Atomic_Compare_Exchange (Item'Address, Prior'Address, Desired);
else
raise Program_Error;
end if;
end Atomic_Compare_And_Exchange;
------------------
-- Is_Lock_Free --
------------------
function Is_Lock_Free (Item : aliased Atomic_Type) return Boolean is
pragma Unreferenced (Item);
use type Interfaces.C.size_t;
begin
return Atomic_Always_Lock_Free (Atomic_Type'Object_Size / 8);
end Is_Lock_Free;
end System.Atomic_Operations.Exchange;
|
