libstdc++-v3/config/cpu/i486/atomicity.h

   1 // Low-level functions for atomic operations: x86, x >= 4 version  -*- C++ -*-
   2
   3 // Copyright (C) 1999-2019 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 #include <ext/atomicity.h>
  26
  27 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  28 {
  29 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  30
  31   _Atomic_word
  32   __attribute__ ((__unused__))
  33   __exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
  34   {
  35     register _Atomic_word __result;
  36     __asm__ __volatile__ ("lock; xadd{l} {%0,%1|%1,%0}"
  37                           : "=r" (__result), "=m" (*__mem)
  38                           : "0" (__val), "m" (*__mem));
  39     return __result;
  40   }
  41
  42   void
  43   __attribute__ ((__unused__))
  44   __atomic_add(volatile _Atomic_word* __mem, int __val) throw ()
  45   {
  46     __asm__ __volatile__ ("lock; add{l} {%1,%0|%0,%1}"
  47                           : "=m" (*__mem) : "ir" (__val), "m" (*__mem));
  48   }
  49
  50 _GLIBCXX_END_NAMESPACE_VERSION
  51 } // namespace
  52