/[pcsx2_0.9.7]/trunk/3rdparty/w32pthreads/sem_trywait.c
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Contents of /trunk/3rdparty/w32pthreads/sem_trywait.c

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Revision 31 - (show annotations) (download)
Tue Sep 7 03:24:11 2010 UTC (9 years, 11 months ago) by william
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committing r3113 initial commit again...
1 /*
2 * -------------------------------------------------------------
3 *
4 * Module: sem_trywait.c
5 *
6 * Purpose:
7 * Semaphores aren't actually part of the PThreads standard.
8 * They are defined by the POSIX Standard:
9 *
10 * POSIX 1003.1b-1993 (POSIX.1b)
11 *
12 * -------------------------------------------------------------
13 *
14 * --------------------------------------------------------------------------
15 *
16 * Pthreads-win32 - POSIX Threads Library for Win32
17 * Copyright(C) 1998 John E. Bossom
18 * Copyright(C) 1999,2005 Pthreads-win32 contributors
19 *
20 * Contact Email: rpj@callisto.canberra.edu.au
21 *
22 * The current list of contributors is contained
23 * in the file CONTRIBUTORS included with the source
24 * code distribution. The list can also be seen at the
25 * following World Wide Web location:
26 * http://sources.redhat.com/pthreads-win32/contributors.html
27 *
28 * This library is free software; you can redistribute it and/or
29 * modify it under the terms of the GNU Lesser General Public
30 * License as published by the Free Software Foundation; either
31 * version 2 of the License, or (at your option) any later version.
32 *
33 * This library is distributed in the hope that it will be useful,
34 * but WITHOUT ANY WARRANTY; without even the implied warranty of
35 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
36 * Lesser General Public License for more details.
37 *
38 * You should have received a copy of the GNU Lesser General Public
39 * License along with this library in the file COPYING.LIB;
40 * if not, write to the Free Software Foundation, Inc.,
41 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
42 */
43
44 #include "ptw32pch.h"
45 #include "semaphore.h"
46
47
48 INLINE int
49 sem_trywait (sem_t * sem)
50 /*
51 * ------------------------------------------------------
52 * DOCPUBLIC
53 * This function tries to wait on a semaphore.
54 *
55 * PARAMETERS
56 * sem
57 * pointer to an instance of sem_t
58 *
59 * DESCRIPTION
60 * This function tries to wait on a semaphore. If the
61 * semaphore value is greater than zero, it decreases
62 * its value by one. If the semaphore value is zero, then
63 * this function returns immediately with the error EAGAIN
64 *
65 * RESULTS
66 * 0 successfully decreased semaphore,
67 * -1 failed, error in errno
68 * ERRNO
69 * EAGAIN the semaphore was already locked,
70 * EINVAL 'sem' is not a valid semaphore,
71 * ENOTSUP sem_trywait is not supported,
72 * EINTR the function was interrupted by a signal,
73 * EDEADLK a deadlock condition was detected.
74 *
75 * ------------------------------------------------------
76 */
77 {
78 int result = 0;
79 sem_t s = *sem;
80
81 if (s == NULL)
82 {
83 result = EINVAL;
84 }
85 else if ((result = pthread_mutex_lock (&s->lock)) == 0)
86 {
87 /* See sem_destroy.c
88 */
89 if (*sem == NULL)
90 {
91 (void) pthread_mutex_unlock (&s->lock);
92 errno = EINVAL;
93 return -1;
94 }
95
96 if (s->value > 0)
97 {
98 s->value--;
99 }
100 else
101 {
102 result = EAGAIN;
103 }
104
105 (void) pthread_mutex_unlock (&s->lock);
106 }
107
108 if (result != 0)
109 {
110 errno = result;
111 return -1;
112 }
113
114 return 0;
115
116 } /* sem_trywait */

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