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/* Copyright (C) 2005, 2008, 2009 Free Software Foundation, Inc.

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

   This file is part of the GNU OpenMP Library (libgomp).

   Libgomp 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, or (at your option)

   any later version.

   Libgomp 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/>.  */

/* This is the default implementation of a barrier synchronization mechanism

   for libgomp.  This type is private to the library.  Note that we rely on

   being able to adjust the barrier count while threads are blocked, so the

   POSIX pthread_barrier_t won't work.  */

#include "libgomp.h"

void

gomp_barrier_init (gomp_barrier_t *bar, unsigned count)

{

  gomp_mutex_init (&bar->mutex1);

#ifndef HAVE_SYNC_BUILTINS

  gomp_mutex_init (&bar->mutex2);

#endif

  gomp_sem_init (&bar->sem1, 0);

  gomp_sem_init (&bar->sem2, 0);

  bar->total = count;

  bar->arrived = 0;

  bar->generation = 0;

}

void

gomp_barrier_destroy (gomp_barrier_t *bar)

{

  /* Before destroying, make sure all threads have left the barrier.  */

  gomp_mutex_lock (&bar->mutex1);

  gomp_mutex_unlock (&bar->mutex1);

  gomp_mutex_destroy (&bar->mutex1);

#ifndef HAVE_SYNC_BUILTINS

  gomp_mutex_destroy (&bar->mutex2);

#endif

  gomp_sem_destroy (&bar->sem1);

  gomp_sem_destroy (&bar->sem2);

}

void

gomp_barrier_reinit (gomp_barrier_t *bar, unsigned count)

{

  gomp_mutex_lock (&bar->mutex1);

  bar->total = count;

  gomp_mutex_unlock (&bar->mutex1);

}

void

gomp_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)

{

  unsigned int n;

  if (state & 1)

    {

      n = --bar->arrived;

      if (n > 0)

        {

          do

            gomp_sem_post (&bar->sem1);

          while (--n != 0);

          gomp_sem_wait (&bar->sem2);

        }

      gomp_mutex_unlock (&bar->mutex1);

    }

  else

    {

      gomp_mutex_unlock (&bar->mutex1);

      gomp_sem_wait (&bar->sem1);

#ifdef HAVE_SYNC_BUILTINS

      n = __sync_add_and_fetch (&bar->arrived, -1);

#else

      gomp_mutex_lock (&bar->mutex2);

      n = --bar->arrived;

      gomp_mutex_unlock (&bar->mutex2);

#endif

      if (n == 0)

        gomp_sem_post (&bar->sem2);

    }

}

void

gomp_barrier_wait (gomp_barrier_t *barrier)

{

  gomp_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier));

}

void

gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)

{

  unsigned int n;

  if (state & 1)

    {

      n = --bar->arrived;

      struct gomp_thread *thr = gomp_thread ();

      struct gomp_team *team = thr->ts.team;

      if (team->task_count)

        {

          gomp_barrier_handle_tasks (state);

          if (n > 0)

            gomp_sem_wait (&bar->sem2);

          gomp_mutex_unlock (&bar->mutex1);

          return;

        }

      bar->generation = state + 3;

      if (n > 0)

        {

          do

            gomp_sem_post (&bar->sem1);

          while (--n != 0);

          gomp_sem_wait (&bar->sem2);

        }

      gomp_mutex_unlock (&bar->mutex1);

    }

  else

    {

      gomp_mutex_unlock (&bar->mutex1);

      do

        {

          gomp_sem_wait (&bar->sem1);

          if (bar->generation & 1)

            gomp_barrier_handle_tasks (state);

        }

      while (bar->generation != state + 4);

#ifdef HAVE_SYNC_BUILTINS

      n = __sync_add_and_fetch (&bar->arrived, -1);

#else

      gomp_mutex_lock (&bar->mutex2);

      n = --bar->arrived;

      gomp_mutex_unlock (&bar->mutex2);

#endif

      if (n == 0)

        gomp_sem_post (&bar->sem2);

    }

}

void

gomp_team_barrier_wait (gomp_barrier_t *barrier)

{

  gomp_team_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier));

}

void

gomp_team_barrier_wake (gomp_barrier_t *bar, int count)

{

  if (count == 0)

    count = bar->total - 1;

  while (count-- > 0)

    gomp_sem_post (&bar->sem1);

}