gcc/libstdc++-v3/config/cpu/i386/bits/atomicity.h

// Low-level functions for atomic operations: x86, x < 4 version  -*- C++ -*-

// Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

#ifndef _BITS_ATOMICITY_H
#define _BITS_ATOMICITY_H	1

typedef int _Atomic_word;

static inline _Atomic_word 
__attribute__ ((__unused__))
__exchange_and_add (volatile _Atomic_word *__mem, int __val)
{
  register _Atomic_word __result;
  __asm__ __volatile__ ("lock; xaddl %0,%2"
			: "=r" (__result) 
                        : "0" (__val), "m" (*__mem) 
                        : "memory");
  return __result;
}

static inline void
__attribute__ ((__unused__))
__atomic_add (volatile _Atomic_word* __mem, int __val)
{
  __asm__ __volatile__ ("lock; addl %0,%1"
			: : "ir" (__val), "m" (*__mem) : "memory");
}

#endif /* atomicity.h */