------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
-- S Y S T E M . M U L T I P R O C E S S O R S . S P I N _ L O C K S --
-- --
-- B o d y --
-- --
-- Copyright (C) 2010-2023, AdaCore --
-- --
-- GNARL 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. GNARL 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/>. --
-- --
------------------------------------------------------------------------------
package body System.Multiprocessors.Spin_Locks is
----------
-- Lock --
----------
procedure Lock (Slock : in out Spin_Lock) is
Succeeded : Boolean;
begin
-- Loop until we can get the lock
loop
Try_Lock (Slock, Succeeded);
exit when Succeeded;
end loop;
end Lock;
------------
-- Locked --
------------
function Locked (Slock : Spin_Lock) return Boolean is
begin
return Slock.Flag /= Unlocked;
end Locked;
--------------
-- Try_Lock --
--------------
procedure Try_Lock (Slock : in out Spin_Lock; Succeeded : out Boolean) is
function Lock_Test_And_Set
(Ptr : access Atomic_Flag;
Value : Atomic_Flag)
return Atomic_Flag;
pragma Import (Intrinsic, Lock_Test_And_Set,
"__sync_lock_test_and_set_1");
begin
Succeeded := (Lock_Test_And_Set (Slock.Flag'Access, 1) = Unlocked);
end Try_Lock;
------------
-- Unlock --
------------
procedure Unlock (Slock : in out Spin_Lock) is
procedure Lock_Release (Ptr : access Atomic_Flag);
pragma Import (Intrinsic, Lock_Release,
"__sync_lock_release_1");
begin
-- Clear Flag. This is a release barrier: all previous memory load
-- are satisfied before this write access.
Lock_Release (Slock.Flag'Access);
end Unlock;
end System.Multiprocessors.Spin_Locks;