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      1 /*
      2  * pthread_spin_unlock.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 (at) 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
     42 pthread_spin_unlock (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   s = *lock;
     52 
     53   if (s == PTHREAD_SPINLOCK_INITIALIZER)
     54     {
     55       return EPERM;
     56     }
     57 
     58   switch ((long)
     59 	  PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG ((PTW32_INTERLOCKED_LONGPTR) &s->interlock,
     60 					      (PTW32_INTERLOCKED_LONG) PTW32_SPIN_UNLOCKED,
     61 					      (PTW32_INTERLOCKED_LONG) PTW32_SPIN_LOCKED))
     62     {
     63     case PTW32_SPIN_LOCKED:
     64     case PTW32_SPIN_UNLOCKED:
     65       return 0;
     66     case PTW32_SPIN_USE_MUTEX:
     67       return pthread_mutex_unlock (&(s->u.mutex));
     68     }
     69 
     70   return EINVAL;
     71 }
     72