1  /* Copyright (C) 2005-2023 Free Software Foundation, Inc.
       2     Contributed by Sebastian Huber <sebastian.huber@embedded-brains.de>.
       3  
       4     This file is part of the GNU OpenMP Library (libgomp).
       5  
       6     Libgomp is free software; you can redistribute it and/or modify it
       7     under the terms of the GNU General Public License as published by
       8     the Free Software Foundation; either version 3, or (at your option)
       9     any later version.
      10  
      11     Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
      12     WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
      13     FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
      14     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  /* This is the RTEMS implementation of a barrier synchronization
      26     mechanism for libgomp.  It is identical to the Linux implementation, except
      27     that the futex API is slightly different.  This type is private to the
      28     library.  */
      29  
      30  #include "libgomp.h"
      31  #include "bar.h"
      32  #include <limits.h>
      33  
      34  static gomp_barrier_t *
      35  generation_to_barrier (int *addr)
      36  {
      37    return (gomp_barrier_t *)
      38  	 ((char *) addr - __builtin_offsetof (gomp_barrier_t, generation));
      39  }
      40  
      41  static void
      42  futex_wait (int *addr, int val)
      43  {
      44    gomp_barrier_t *bar = generation_to_barrier (addr);
      45    _Futex_Wait (&bar->futex, addr, val);
      46  }
      47  
      48  static void
      49  futex_wake (int *addr, int count)
      50  {
      51    gomp_barrier_t *bar = generation_to_barrier (addr);
      52    _Futex_Wake (&bar->futex, count);
      53  }
      54  
      55  static int
      56  do_spin (int *addr, int val)
      57  {
      58    unsigned long long i, count = gomp_spin_count_var;
      59  
      60    if (__builtin_expect (gomp_managed_threads > gomp_available_cpus, 0))
      61      count = gomp_throttled_spin_count_var;
      62    for (i = 0; i < count; i++)
      63      if (__builtin_expect (__atomic_load_n (addr, MEMMODEL_RELAXED) != val, 0))
      64        return 0;
      65    return 1;
      66  }
      67  
      68  static void
      69  do_wait (int *addr, int val)
      70  {
      71    if (do_spin (addr, val))
      72      futex_wait (addr, val);
      73  }
      74  
      75  #define GOMP_WAIT_H 1
      76  #include "../linux/bar.c"