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// Low-level type for atomic operations -*- C++ -*-

// Copyright (C) 2004 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,

// 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 _GLIBCXX_ATOMIC_WORD_H

#define _GLIBCXX_ATOMIC_WORD_H  1

#include <cxxabi.h>

typedef int _Atomic_word;

namespace __gnu_cxx

{

  // Test the first byte of __g and ensure that no loads are hoisted across

  // the test.

  inline bool

  __test_and_acquire (__cxxabiv1::__guard *__g)

  {

    unsigned char __c;

    unsigned char *__p = reinterpret_cast<unsigned char *>(__g);

    // ldN.acq is a load with an implied hoist barrier.

    // would ld8+mask be faster than just doing an ld1?

    __asm __volatile ("ld1.acq %0 = %1" : "=r"(__c) : "m"(*__p) : "memory");

    return __c != 0;

  }

  // Set the first byte of __g to 1 and ensure that no stores are sunk

  // across the store.

  inline void

  __set_and_release (__cxxabiv1::__guard *__g)

  {

    unsigned char *__p = reinterpret_cast<unsigned char *>(__g);

    // stN.rel is a store with an implied sink barrier.

    // could load word, set flag, and CAS it back

    __asm __volatile ("st1.rel %0 = %1" : "=m"(*__p) : "r"(1) : "memory");

  }

  // We don't define the _BARRIER macros on ia64 because the barriers are

  // included in the test and set, above.

#define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(G) __gnu_cxx::__test_and_acquire (G)

#define _GLIBCXX_GUARD_SET_AND_RELEASE(G) __gnu_cxx::__set_and_release (G)

}

#endif