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/* Copyright (C) 2008, 2009, 2011 Free Software Foundation, Inc.

   Contributed by Richard Henderson <rth@redhat.com>.

   This file is part of the GNU Transactional Memory Library (libitm).

   Libitm 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 3 of the License, or

   (at your option) any later version.

   Libitm 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.

   Under Section 7 of GPL version 3, you are granted additional

   permissions described in the GCC Runtime Library Exception, version

   3.1, as published by the Free Software Foundation.

   You should have received a copy of the GNU General Public License and

   a copy of the GCC Runtime Library Exception along with this program;

   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

   <http://www.gnu.org/licenses/>.  */

/* Provide access to the futex system call.  */

#include "libitm_i.h"

#include "futex.h"

#include <futex_bits.h>

#include <errno.h>

namespace GTM HIDDEN {

#define FUTEX_WAIT              0

#define FUTEX_WAKE              1

#define FUTEX_PRIVATE_FLAG      128L

static long int gtm_futex_wait = FUTEX_WAIT | FUTEX_PRIVATE_FLAG;

static long int gtm_futex_wake = FUTEX_WAKE | FUTEX_PRIVATE_FLAG;

void

futex_wait (std::atomic<int> *addr, int val)

{

  long res;

  res = sys_futex0 (addr, gtm_futex_wait, val);

  if (__builtin_expect (res == -ENOSYS, 0))

    {

      gtm_futex_wait = FUTEX_WAIT;

      gtm_futex_wake = FUTEX_WAKE;

      res = sys_futex0 (addr, FUTEX_WAIT, val);

    }

  if (__builtin_expect (res < 0, 0))

    {

      if (res == -EWOULDBLOCK || res == -ETIMEDOUT)

        ;

      else if (res == -EFAULT)

        GTM_fatal ("futex failed (EFAULT %p)", addr);

      else

        GTM_fatal ("futex failed (%s)", strerror(-res));

    }

}

long

futex_wake (std::atomic<int> *addr, int count)

{

  long res = sys_futex0 (addr, gtm_futex_wake, count);

  if (__builtin_expect (res == -ENOSYS, 0))

    {

      gtm_futex_wait = FUTEX_WAIT;

      gtm_futex_wake = FUTEX_WAKE;

      res = sys_futex0 (addr, FUTEX_WAKE, count);

    }

  if (__builtin_expect (res < 0, 0))

    GTM_fatal ("futex failed (%s)", strerror(-res));

  else

    return res;

}

} // namespace GTM