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tasks/libposix/include/posix/bits/atomic.h

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+/* Copyright (C) 2003 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef _BITS_ATOMIC_H
+#define _BITS_ATOMIC_H	1
+
+/* We have by default no support for atomic operations.  So define
+   them non-atomic.  If this is a problem somebody will have to come
+   up with real definitions.  */
+
+/* The only basic operation needed is compare and exchange.  */
+#define atomic_compare_and_exchange_val_acq(mem, newval, oldval) \
+  ({ __typeof (mem) __gmemp = (mem);				      \
+     __typeof (*mem) __gret = *__gmemp;				      \
+     __typeof (*mem) __gnewval = (newval);			      \
+								      \
+     if (__gret == (oldval))					      \
+       *__gmemp = __gnewval;					      \
+     __gret; })
+
+#define atomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
+  ({ __typeof (mem) __gmemp = (mem);				      \
+     __typeof (*mem) __gnewval = (newval);			      \
+								      \
+     *__gmemp == (oldval) ? (*__gmemp = __gnewval, 0) : 1; })
+
+#endif	/* bits/atomic.h */