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1 /* Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc.
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2 Contributed by Richard Henderson <rth@redhat.com>.
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3
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4 This file is part of the GNU OpenMP Library (libgomp).
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5
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6 Libgomp is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 3, or (at your option)
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9 any later version.
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10
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11 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
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12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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13 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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14 more details.
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15
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16 Under Section 7 of GPL version 3, you are granted additional
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17 permissions described in the GCC Runtime Library Exception, version
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18 3.1, as published by the Free Software Foundation.
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19
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20 You should have received a copy of the GNU General Public License and
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21 a copy of the GCC Runtime Library Exception along with this program;
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22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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23 <http://www.gnu.org/licenses/>. */
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24
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25 /* This is the default POSIX 1003.1b implementation of a semaphore
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26 synchronization mechanism for libgomp. This type is private to
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27 the library.
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28
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29 This is a bit heavy weight for what we need, in that we're not
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30 interested in sem_wait as a cancelation point, but it's not too
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31 bad for a default. */
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32
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33 #include "libgomp.h"
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34
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35 #ifdef HAVE_BROKEN_POSIX_SEMAPHORES
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36 #include <stdlib.h>
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37
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38 void gomp_sem_init (gomp_sem_t *sem, int value)
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39 {
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40 int ret;
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41
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42 ret = pthread_mutex_init (&sem->mutex, NULL);
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43 if (ret)
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44 return;
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45
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46 ret = pthread_cond_init (&sem->cond, NULL);
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47 if (ret)
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48 return;
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49
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50 sem->value = value;
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51 }
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52
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53 void gomp_sem_wait (gomp_sem_t *sem)
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54 {
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55 int ret;
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56
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57 ret = pthread_mutex_lock (&sem->mutex);
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58 if (ret)
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59 return;
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60
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61 if (sem->value > 0)
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62 {
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63 sem->value--;
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64 ret = pthread_mutex_unlock (&sem->mutex);
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65 return;
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66 }
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67
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68 while (sem->value <= 0)
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69 {
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70 ret = pthread_cond_wait (&sem->cond, &sem->mutex);
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71 if (ret)
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72 {
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73 pthread_mutex_unlock (&sem->mutex);
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74 return;
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75 }
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76 }
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77
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78 sem->value--;
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79 ret = pthread_mutex_unlock (&sem->mutex);
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80 return;
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81 }
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82
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83 void gomp_sem_post (gomp_sem_t *sem)
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84 {
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85 int ret;
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86
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87 ret = pthread_mutex_lock (&sem->mutex);
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88 if (ret)
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89 return;
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90
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91 sem->value++;
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92
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93 ret = pthread_mutex_unlock (&sem->mutex);
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94 if (ret)
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95 return;
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96
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97 ret = pthread_cond_signal (&sem->cond);
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98
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99 return;
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100 }
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101
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102 void gomp_sem_destroy (gomp_sem_t *sem)
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103 {
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104 int ret;
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105
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106 ret = pthread_mutex_destroy (&sem->mutex);
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107 if (ret)
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108 return;
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109
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110 ret = pthread_cond_destroy (&sem->cond);
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111
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112 return;
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113 }
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114 #else /* HAVE_BROKEN_POSIX_SEMAPHORES */
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115 void
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116 gomp_sem_wait (gomp_sem_t *sem)
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117 {
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118 /* With POSIX, the wait can be canceled by signals. We don't want that.
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119 It is expected that the return value here is -1 and errno is EINTR. */
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120 while (sem_wait (sem) != 0)
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121 continue;
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122 }
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123 #endif
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