source: trunk/sys/libgomp/sem.c @ 1

Last change on this file since 1 was 1, checked in by alain, 5 years ago

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[1]1/* Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc.
2   Contributed by Richard Henderson <rth@redhat.com>.
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 default POSIX 1003.1b implementation of a semaphore
26   synchronization mechanism for libgomp.  This type is private to
27   the library.
28
29   This is a bit heavy weight for what we need, in that we're not
30   interested in sem_wait as a cancelation point, but it's not too
31   bad for a default.  */
32
33#include <gomp/libgomp.h>
34
35#ifdef HAVE_BROKEN_POSIX_SEMAPHORES
36#include <stdlib.h>
37
38void gomp_sem_init (gomp_sem_t *sem, int value)
39{
40  int ret;
41
42  ret = pthread_mutex_init (&sem->mutex, NULL);
43  if (ret)
44    return;
45
46  ret = pthread_cond_init (&sem->cond, NULL);
47  if (ret)
48    return;
49
50  sem->value = value;
51}
52
53void gomp_sem_wait (gomp_sem_t *sem)
54{
55  int ret;
56
57  ret = pthread_mutex_lock (&sem->mutex);
58  if (ret)
59    return;
60
61  if (sem->value > 0)
62    {
63      sem->value--;
64      ret = pthread_mutex_unlock (&sem->mutex);
65      return;
66    }
67
68  while (sem->value <= 0)
69    {
70      ret = pthread_cond_wait (&sem->cond, &sem->mutex);
71      if (ret)
72        {
73          pthread_mutex_unlock (&sem->mutex);
74          return;
75        }
76    }
77
78  sem->value--;
79  ret = pthread_mutex_unlock (&sem->mutex);
80  return;
81}
82
83void gomp_sem_post (gomp_sem_t *sem)
84{
85  int ret;
86
87  ret = pthread_mutex_lock (&sem->mutex);
88  if (ret)
89    return;
90
91  sem->value++;
92
93  ret = pthread_mutex_unlock (&sem->mutex);
94  if (ret)
95    return;
96
97  ret = pthread_cond_signal (&sem->cond);
98
99  return;
100}
101
102void gomp_sem_destroy (gomp_sem_t *sem)
103{
104  int ret;
105
106  ret = pthread_mutex_destroy (&sem->mutex);
107  if (ret)
108    return;
109
110  ret = pthread_cond_destroy (&sem->cond);
111
112  return;
113}
114#else /* HAVE_BROKEN_POSIX_SEMAPHORES  */
115void
116gomp_sem_wait (gomp_sem_t *sem)
117{
118  /* With POSIX, the wait can be canceled by signals.  We don't want that.
119     It is expected that the return value here is -1 and errno is EINTR.  */
120  while (sem_wait (sem) != 0)
121    continue;
122}
123#endif
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