| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT RUN-TIME COMPONENTS -- |
| -- -- |
| -- S Y S T E M . A T O M I C _ P R I M I T I V E S -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 2012-2022, 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. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| package body System.Atomic_Primitives is |
| |
| -------------------- |
| -- Lock_Free_Read -- |
| -------------------- |
| |
| function Lock_Free_Read (Ptr : Address) return Atomic_Type is |
| function My_Atomic_Load is new Atomic_Load (Atomic_Type); |
| |
| begin |
| if Atomic_Type'Atomic_Always_Lock_Free then |
| return My_Atomic_Load (Ptr, Acquire); |
| else |
| raise Program_Error; |
| end if; |
| end Lock_Free_Read; |
| |
| ------------------------- |
| -- Lock_Free_Try_Write -- |
| ------------------------- |
| |
| function Lock_Free_Try_Write |
| (Ptr : Address; |
| Expected : in out Atomic_Type; |
| Desired : Atomic_Type) return Boolean |
| is |
| function My_Atomic_Compare_Exchange is |
| new Atomic_Compare_Exchange (Atomic_Type); |
| |
| begin |
| if Expected /= Desired then |
| if Atomic_Type'Atomic_Always_Lock_Free then |
| return My_Atomic_Compare_Exchange (Ptr, Expected'Address, Desired); |
| else |
| raise Program_Error; |
| end if; |
| end if; |
| |
| return True; |
| end Lock_Free_Try_Write; |
| |
| end System.Atomic_Primitives; |
