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, write to the Free
   17:    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   18:    02111-1307 USA.  */
   19: 
   20: #ifndef _BITS_ATOMIC_H
   21: #define _BITS_ATOMIC_H  1
   22: 
   23: /* We have by default no support for atomic operations.  So define
   24:    them non-atomic.  If this is a problem somebody will have to come
   25:    up with real definitions.  */
   26: 
   27: /* The only basic operation needed is compare and exchange.  */
   28: #define atomic_compare_and_exchange_val_acq(mem, newval, oldval) \
   29:   ({ __typeof (mem) __gmemp = (mem);                                  \
   30:      __typeof (*mem) __gret = *__gmemp;                               \
   31:      __typeof (*mem) __gnewval = (newval);                            \
   32:                                                                       \
   33:      if (__gret == (oldval))                                          \
   34:        *__gmemp = __gnewval;                                          \
   35:      __gret; })
   36: 
   37: #define atomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
   38:   ({ __typeof (mem) __gmemp = (mem);                                  \
   39:      __typeof (*mem) __gnewval = (newval);                            \
   40:                                                                       \
   41:      *__gmemp == (oldval) ? (*__gmemp = __gnewval, 0) : 1; })
   42: 
   43: #endif  /* bits/atomic.h */