/[pcsx2_0.9.7]/trunk/3rdparty/w32pthreads/pthread_rwlock_rdlock.c
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Contents of /trunk/3rdparty/w32pthreads/pthread_rwlock_rdlock.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
File MIME type: text/plain
File size: 2887 byte(s)
committing r3113 initial commit again...
1 /*
2 * pthread_rwlock_rdlock.c
3 *
4 * Description:
5 * This translation unit implements read/write lock primitives.
6 *
7 * --------------------------------------------------------------------------
8 *
9 * Pthreads-win32 - POSIX Threads Library for Win32
10 * Copyright(C) 1998 John E. Bossom
11 * Copyright(C) 1999,2005 Pthreads-win32 contributors
12 *
13 * Contact Email: rpj@callisto.canberra.edu.au
14 *
15 * The current list of contributors is contained
16 * in the file CONTRIBUTORS included with the source
17 * code distribution. The list can also be seen at the
18 * following World Wide Web location:
19 * http://sources.redhat.com/pthreads-win32/contributors.html
20 *
21 * This library is free software; you can redistribute it and/or
22 * modify it under the terms of the GNU Lesser General Public
23 * License as published by the Free Software Foundation; either
24 * version 2 of the License, or (at your option) any later version.
25 *
26 * This library is distributed in the hope that it will be useful,
27 * but WITHOUT ANY WARRANTY; without even the implied warranty of
28 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
29 * Lesser General Public License for more details.
30 *
31 * You should have received a copy of the GNU Lesser General Public
32 * License along with this library in the file COPYING.LIB;
33 * if not, write to the Free Software Foundation, Inc.,
34 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
35 */
36
37 #include "ptw32pch.h"
38
39 int
40 pthread_rwlock_rdlock (pthread_rwlock_t * rwlock)
41 {
42 int result;
43 pthread_rwlock_t rwl;
44
45 if (rwlock == NULL || *rwlock == NULL)
46 {
47 return EINVAL;
48 }
49
50 /*
51 * We do a quick check to see if we need to do more work
52 * to initialise a static rwlock. We check
53 * again inside the guarded section of ptw32_rwlock_check_need_init()
54 * to avoid race conditions.
55 */
56 if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
57 {
58 result = ptw32_rwlock_check_need_init (rwlock);
59
60 if (result != 0 && result != EBUSY)
61 {
62 return result;
63 }
64 }
65
66 rwl = *rwlock;
67
68 if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
69 {
70 return EINVAL;
71 }
72
73 if ((result = pthread_mutex_lock (&(rwl->mtxExclusiveAccess))) != 0)
74 {
75 return result;
76 }
77
78 if (++rwl->nSharedAccessCount == INT_MAX)
79 {
80 if ((result =
81 pthread_mutex_lock (&(rwl->mtxSharedAccessCompleted))) != 0)
82 {
83 (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
84 return result;
85 }
86
87 rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
88 rwl->nCompletedSharedAccessCount = 0;
89
90 if ((result =
91 pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted))) != 0)
92 {
93 (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
94 return result;
95 }
96 }
97
98 return (pthread_mutex_unlock (&(rwl->mtxExclusiveAccess)));
99 }

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