1  // Low-level functions for atomic operations: x86, x >= 4 version  -*- C++ -*-
       2  
       3  // Copyright (C) 1999-2023 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