1  /* Copyright (C) 2003-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library.  If not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #ifndef _ATOMIC_MACHINE_H
      19  #define _ATOMIC_MACHINE_H	1
      20  
      21  /* If we have just non-atomic operations, we can as well make them wide.  */
      22  #define __HAVE_64B_ATOMICS 1
      23  #define USE_ATOMIC_COMPILER_BUILTINS 0
      24  
      25  /* XXX Is this actually correct?  */
      26  #define ATOMIC_EXCHANGE_USES_CAS 1
      27  
      28  /* The only basic operation needed is compare and exchange.  */
      29  #define atomic_compare_and_exchange_val_acq(mem, newval, oldval) \
      30    ({ __typeof (mem) __gmemp = (mem);				      \
      31       __typeof (*mem) __gret = *__gmemp;				      \
      32       __typeof (*mem) __gnewval = (newval);			      \
      33  								      \
      34       if (__gret == (oldval))					      \
      35         *__gmemp = __gnewval;					      \
      36       __gret; })
      37  
      38  #define atomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
      39    ({ __typeof (mem) __gmemp = (mem);				      \
      40       __typeof (*mem) __gnewval = (newval);			      \
      41  								      \
      42       *__gmemp == (oldval) ? (*__gmemp = __gnewval, 0) : 1; })
      43  
      44  #endif