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

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Revision 280 - (show annotations) (download)
Thu Dec 23 12:02:12 2010 UTC (9 years, 2 months ago) by william
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re-commit (had local access denied errors when committing)
1 /*
2 * pthread_barrier_wait.c
3 *
4 * Description:
5 * This translation unit implements barrier 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
40 int
41 pthread_barrier_wait (pthread_barrier_t * barrier)
42 {
43 int result;
44 int step;
45 pthread_barrier_t b;
46
47 if (barrier == NULL || *barrier == (pthread_barrier_t) PTW32_OBJECT_INVALID)
48 {
49 return EINVAL;
50 }
51
52 b = *barrier;
53 step = b->iStep;
54
55 if (0 == InterlockedDecrement ((long *) &(b->nCurrentBarrierHeight)))
56 {
57 /* Must be done before posting the semaphore. */
58 b->nCurrentBarrierHeight = b->nInitialBarrierHeight;
59
60 /*
61 * There is no race condition between the semaphore wait and post
62 * because we are using two alternating semas and all threads have
63 * entered barrier_wait and checked nCurrentBarrierHeight before this
64 * barrier's sema can be posted. Any threads that have not quite
65 * entered sem_wait below when the multiple_post has completed
66 * will nevertheless continue through the semaphore (barrier)
67 * and will not be left stranded.
68 */
69 result = (b->nInitialBarrierHeight > 1
70 ? sem_post_multiple (&(b->semBarrierBreeched[step]),
71 b->nInitialBarrierHeight - 1) : 0);
72 }
73 else
74 {
75 /*
76 * Use the non-cancelable version of sem_wait().
77 */
78 result = ptw32_semwait (&(b->semBarrierBreeched[step]));
79 }
80
81 /*
82 * The first thread across will be the PTHREAD_BARRIER_SERIAL_THREAD.
83 * This also sets up the alternate semaphore as the next barrier.
84 */
85 if (0 == result)
86 {
87 result = ( step ==
88 _InterlockedCompareExchange ( &(b->iStep), (1L - step), step) ?
89 PTHREAD_BARRIER_SERIAL_THREAD : 0);
90 }
91
92 return (result);
93 }

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