1 /*
2 * pthread_barrier_init.c
3 *
4 * Description:
5 * This translation unit implements barrier primitives.
6 *
7 * --------------------------------------------------------------------------
8 *
9 * Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems
10 * Copyright(C) 2008 Jason Schmidlapp
11 *
12 * Contact Email: jschmidlapp@users.sourceforge.net
13 *
14 *
15 * Based upon Pthreads-win32 - POSIX Threads Library for Win32
16 * Copyright(C) 1998 John E. Bossom
17 * Copyright(C) 1999,2005 Pthreads-win32 contributors
18 *
19 * Contact Email: rpj@callisto.canberra.edu.au
20 *
21 * The original list of contributors to the Pthreads-win32 project
22 * is contained in the file CONTRIBUTORS.ptw32 included with the
23 * source code distribution. The list can also be seen at the
24 * following World Wide Web location:
25 * http://sources.redhat.com/pthreads-win32/contributors.html
26 *
27 * This library is free software; you can redistribute it and/or
28 * modify it under the terms of the GNU Lesser General Public
29 * License as published by the Free Software Foundation; either
30 * version 2 of the License, or (at your option) any later version.
31 *
32 * This library is distributed in the hope that it will be useful,
33 * but WITHOUT ANY WARRANTY; without even the implied warranty of
34 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
35 * Lesser General Public License for more details.
36 *
37 * You should have received a copy of the GNU Lesser General Public
38 * License along with this library in the file COPYING.LIB;
39 * if not, write to the Free Software Foundation, Inc.,
40 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
41 */
42
43 #include <stdlib.h>
44
45 #include "pthread.h"
46 #include "implement.h"
47
48
49 int
pthread_barrier_init(pthread_barrier_t * barrier,const pthread_barrierattr_t * attr,unsigned int count)50 pthread_barrier_init (pthread_barrier_t * barrier,
51 const pthread_barrierattr_t * attr, unsigned int count)
52 {
53 pthread_barrier_t b;
54
55 if (barrier == NULL || count == 0)
56 {
57 return EINVAL;
58 }
59
60 if (NULL != (b = (pthread_barrier_t) calloc (1, sizeof (*b))))
61 {
62 b->pshared = (attr != NULL && *attr != NULL
63 ? (*attr)->pshared : PTHREAD_PROCESS_PRIVATE);
64
65 b->nCurrentBarrierHeight = b->nInitialBarrierHeight = count;
66 b->iStep = 0;
67
68 /*
69 * Two semaphores are used in the same way as two stepping
70 * stones might be used in crossing a stream. Once all
71 * threads are safely on one stone, the other stone can
72 * be moved ahead, and the threads can start moving to it.
73 * If some threads decide to eat their lunch before moving
74 * then the other threads have to wait.
75 */
76 if (0 == sem_init (&(b->semBarrierBreeched[0]), b->pshared, 0))
77 {
78 if (0 == sem_init (&(b->semBarrierBreeched[1]), b->pshared, 0))
79 {
80 *barrier = b;
81 return 0;
82 }
83 (void) sem_destroy (&(b->semBarrierBreeched[0]));
84 }
85 (void) free (b);
86 }
87
88 return ENOMEM;
89 }
90