glibc/bits/atomic.h

32 lines
1.3 KiB
C

/* 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 arch_compare_and_exchange_acq(mem, newval, oldval) \
({ *(mem) == (oldval) ? 1 : (*(mem) = (newval), 0); })
#endif /* bits/atomic.h */