native_client_sdk/src/libraries/third_party/pthreads-win32/pthread_spin_trylock.c

   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
  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 }