sysdeps/generic/atomic-machine.h

   1 /* Copyright (C) 2003-2019 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    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _ATOMIC_MACHINE_H
  20 #define _ATOMIC_MACHINE_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  /* atomic-machine.h */