1  /* Low-level functions for atomic operations. ARC version.
       2     Copyright (C) 2020-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       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 _ARC_BITS_ATOMIC_H
      20  #define _ARC_BITS_ATOMIC_H 1
      21  
      22  #define __HAVE_64B_ATOMICS 0
      23  #define USE_ATOMIC_COMPILER_BUILTINS 1
      24  
      25  /* ARC does have legacy atomic EX reg, [mem] instruction but the micro-arch
      26     is not as optimal as LLOCK/SCOND specially for SMP.  */
      27  #define ATOMIC_EXCHANGE_USES_CAS 1
      28  
      29  #define __arch_compare_and_exchange_bool_8_acq(mem, newval, oldval)	\
      30    (abort (), 0)
      31  #define __arch_compare_and_exchange_bool_16_acq(mem, newval, oldval)	\
      32    (abort (), 0)
      33  #define __arch_compare_and_exchange_bool_64_acq(mem, newval, oldval)	\
      34    (abort (), 0)
      35  
      36  #define __arch_compare_and_exchange_val_8_int(mem, newval, oldval, model)	\
      37    (abort (), (__typeof (*mem)) 0)
      38  #define __arch_compare_and_exchange_val_16_int(mem, newval, oldval, model)	\
      39    (abort (), (__typeof (*mem)) 0)
      40  #define __arch_compare_and_exchange_val_64_int(mem, newval, oldval, model)	\
      41    (abort (), (__typeof (*mem)) 0)
      42  
      43  #define __arch_compare_and_exchange_val_32_int(mem, newval, oldval, model)	\
      44    ({										\
      45      typeof (*mem) __oldval = (oldval);                                  	\
      46      __atomic_compare_exchange_n (mem, (void *) &__oldval, newval, 0,    	\
      47                                   model, __ATOMIC_RELAXED);              	\
      48      __oldval;                                                           	\
      49    })
      50  
      51  #define atomic_compare_and_exchange_val_acq(mem, new, old)		\
      52    __atomic_val_bysize (__arch_compare_and_exchange_val, int,		\
      53  		       mem, new, old, __ATOMIC_ACQUIRE)
      54  
      55  #define atomic_full_barrier()  ({ asm volatile ("dmb 3":::"memory"); })
      56  
      57  #endif /* _ARC_BITS_ATOMIC_H */