1 /*
2 * pthread_spin_trylock.c
3 *
4 * Description:
5 * This translation unit implements spin 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 "pthread.h"
38 #include "implement.h"
39
40
41 int
pthread_spin_trylock(pthread_spinlock_t * lock)42 pthread_spin_trylock (pthread_spinlock_t * lock)
43 {
44 register pthread_spinlock_t s;
45
46 if (NULL == lock || NULL == *lock)
47 {
48 return (EINVAL);
49 }
50
51 if (*lock == PTHREAD_SPINLOCK_INITIALIZER)
52 {
53 int result;
54
55 if ((result = ptw32_spinlock_check_need_init (lock)) != 0)
56 {
57 return (result);
58 }
59 }
60
61 s = *lock;
62
63 switch ((long)
64 PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG ((PTW32_INTERLOCKED_LONGPTR) &s->interlock,
65 (PTW32_INTERLOCKED_LONG) PTW32_SPIN_LOCKED,
66 (PTW32_INTERLOCKED_LONG) PTW32_SPIN_UNLOCKED))
67 {
68 case PTW32_SPIN_UNLOCKED:
69 return 0;
70 case PTW32_SPIN_LOCKED:
71 return EBUSY;
72 case PTW32_SPIN_USE_MUTEX:
73 return pthread_mutex_trylock (&(s->u.mutex));
74 }
75
76 return EINVAL;
77 }
78