1 // Low-level type for atomic operations -*- C++ -*-
3 // Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
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 2, or (at your option)
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.
16 // You should have received a copy of the GNU General Public License along
17 // with this library; see the file COPYING. If not, write to the Free
18 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
21 // As a special exception, you may use this file as part of a free software
22 // library without restriction. Specifically, if other files instantiate
23 // templates or use macros or inline functions from this file, or you compile
24 // this file and link it with other files to produce an executable, this
25 // file does not by itself cause the resulting executable to be covered by
26 // the GNU General Public License. This exception does not however
27 // invalidate any other reasons why the executable file might be covered by
28 // the GNU General Public License.
30 #ifndef _GLIBCXX_ATOMIC_WORD_H
31 #define _GLIBCXX_ATOMIC_WORD_H 1
33 #include <bits/cxxabi_tweaks.h>
35 typedef int _Atomic_word;
39 // Test the first byte of __g and ensure that no loads are hoisted across
42 __test_and_acquire (__cxxabiv1::__guard *__g)
45 unsigned char *__p = reinterpret_cast<unsigned char *>(__g);
46 // ldN.acq is a load with an implied hoist barrier.
47 // would ld8+mask be faster than just doing an ld1?
48 __asm __volatile ("ld1.acq %0 = %1" : "=r"(__c) : "m"(*__p) : "memory");
52 // Set the first byte of __g to 1 and ensure that no stores are sunk
55 __set_and_release (__cxxabiv1::__guard *__g)
57 unsigned char *__p = reinterpret_cast<unsigned char *>(__g);
58 // stN.rel is a store with an implied sink barrier.
59 // could load word, set flag, and CAS it back
60 __asm __volatile ("st1.rel %0 = %1" : "=m"(*__p) : "r"(1) : "memory");
63 // We don't define the _BARRIER macros on ia64 because the barriers are
64 // included in the test and set, above.
65 #define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(G) __gnu_cxx::__test_and_acquire (G)
66 #define _GLIBCXX_GUARD_SET_AND_RELEASE(G) __gnu_cxx::__set_and_release (G)