1// Low-level functions for atomic operations: Generic version -*- C++ -*- 2 3// Copyright (C) 1999-2020 Free Software Foundation, Inc. 4// 5// This file is part of the GNU ISO C++ Library. This library is free 6// software; you can redistribute it and/or modify it under the 7// terms of the GNU General Public License as published by the 8// Free Software Foundation; either version 3, or (at your option) 9// any later version. 10 11// This library is distributed in the hope that it will be useful, 12// but WITHOUT ANY WARRANTY; without even the implied warranty of 13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14// GNU General Public License for more details. 15 16// Under Section 7 of GPL version 3, you are granted additional 17// permissions described in the GCC Runtime Library Exception, version 18// 3.1, as published by the Free Software Foundation. 19 20// You should have received a copy of the GNU General Public License and 21// a copy of the GCC Runtime Library Exception along with this program; 22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23// <http://www.gnu.org/licenses/>. 24 25#include <ext/atomicity.h> 26#include <ext/concurrence.h> 27 28namespace 29{ 30 __gnu_cxx::__mutex& 31 get_atomic_mutex() 32 { 33 static __gnu_cxx::__mutex atomic_mutex; 34 return atomic_mutex; 35 } 36} // anonymous namespace 37 38namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 39{ 40_GLIBCXX_BEGIN_NAMESPACE_VERSION 41 42 _Atomic_word 43 __attribute__ ((__unused__)) 44 __exchange_and_add(volatile _Atomic_word* __mem, int __val) throw () 45 { 46 __gnu_cxx::__scoped_lock sentry(get_atomic_mutex()); 47 _Atomic_word __result; 48 __result = *__mem; 49 *__mem += __val; 50 return __result; 51 } 52 53 void 54 __attribute__ ((__unused__)) 55 __atomic_add(volatile _Atomic_word* __mem, int __val) throw () 56 { __exchange_and_add(__mem, __val); } 57 58_GLIBCXX_END_NAMESPACE_VERSION 59} // namespace 60