1 /*
2  * pthread_spin_lock.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  *      51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
35  */
36 
37 #include "pthread.h"
38 #include "implement.h"
39 
40 
41 int
pthread_spin_lock(pthread_spinlock_t * lock)42 pthread_spin_lock (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   while ((PTW32_INTERLOCKED_LONG) PTW32_SPIN_LOCKED ==
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     }
69 
70   if (s->interlock == PTW32_SPIN_LOCKED)
71     {
72       return 0;
73     }
74   else if (s->interlock == PTW32_SPIN_USE_MUTEX)
75     {
76       return pthread_mutex_lock (&(s->u.mutex));
77     }
78 
79   return EINVAL;
80 }
81