1 /* Copyright (C) 2003 Free Software Foundation, Inc. 2 This file is part of the GNU C Library. 3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2003. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <http://www.gnu.org/licenses/>. */ 18 19 #ifndef _BITS_ATOMIC_H 20 #define _BITS_ATOMIC_H 1 21 22 /* We have by default no support for atomic operations. So define 23 them non-atomic. If this is a problem somebody will have to come 24 up with real definitions. */ 25 26 /* The only basic operation needed is compare and exchange. */ 27 #define atomic_compare_and_exchange_val_acq(mem, newval, oldval) \ 28 ({ __typeof (mem) __gmemp = (mem); \ 29 __typeof (*mem) __gret = *__gmemp; \ 30 __typeof (*mem) __gnewval = (newval); \ 31 \ 32 if (__gret == (oldval)) \ 33 *__gmemp = __gnewval; \ 34 __gret; }) 35 36 #define atomic_compare_and_exchange_bool_acq(mem, newval, oldval) \ 37 ({ __typeof (mem) __gmemp = (mem); \ 38 __typeof (*mem) __gnewval = (newval); \ 39 \ 40 *__gmemp == (oldval) ? (*__gmemp = __gnewval, 0) : 1; }) 41 42 #endif /* bits/atomic.h */ 43