1// Low-level type for atomic operations -*- C++ -*- 2 3// Copyright (C) 2004, 2005, 2006, 2007, 2009 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#ifndef _GLIBCXX_ATOMIC_WORD_H 26#define _GLIBCXX_ATOMIC_WORD_H 1 27 28#include <bits/cxxabi_tweaks.h> 29 30typedef int _Atomic_word; 31 32namespace __gnu_cxx 33{ 34 // Test the first byte of __g and ensure that no loads are hoisted across 35 // the test. 36 inline bool 37 __test_and_acquire (__cxxabiv1::__guard *__g) 38 { 39 unsigned char __c; 40 unsigned char *__p = reinterpret_cast<unsigned char *>(__g); 41 // ldN.acq is a load with an implied hoist barrier. 42 // would ld8+mask be faster than just doing an ld1? 43 __asm __volatile ("ld1.acq %0 = %1" : "=r"(__c) : "m"(*__p) : "memory"); 44 return __c != 0; 45 } 46 47 // Set the first byte of __g to 1 and ensure that no stores are sunk 48 // across the store. 49 inline void 50 __set_and_release (__cxxabiv1::__guard *__g) 51 { 52 unsigned char *__p = reinterpret_cast<unsigned char *>(__g); 53 // stN.rel is a store with an implied sink barrier. 54 // could load word, set flag, and CAS it back 55 __asm __volatile ("st1.rel %0 = %1" : "=m"(*__p) : "r"(1) : "memory"); 56 } 57 58 // We don't define the _BARRIER macros on ia64 because the barriers are 59 // included in the test and set, above. 60#define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(G) __gnu_cxx::__test_and_acquire (G) 61#define _GLIBCXX_GUARD_SET_AND_RELEASE(G) __gnu_cxx::__set_and_release (G) 62} 63 64#endif 65