text: /*
   * pthread_spin_trylock.c
   *
   * Description:
   * This translation unit implements spin lock primitives.
   *
   * --------------------------------------------------------------------------
   *
   *      Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems
   *      Copyright(C) 2008 Jason Schmidlapp
   *
   *      Contact Email: jschmidlapp@users.sourceforge.net
   *
   *
   *      Based upon Pthreads-win32 - POSIX Threads Library for Win32
   *      Copyright(C) 1998 John E. Bossom
   *      Copyright(C) 1999,2005 Pthreads-win32 contributors
   *
   *      Contact Email: rpj@callisto.canberra.edu.au
   *
   *      The original list of contributors to the Pthreads-win32 project
   *      is contained in the file CONTRIBUTORS.ptw32 included with the
   *      source code distribution. The list can also be seen at the
   *      following World Wide Web location:
   *      http://sources.redhat.com/pthreads-win32/contributors.html
   *
   *      This library is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU Lesser General Public
   *      License as published by the Free Software Foundation; either
   *      version 2 of the License, or (at your option) any later version.
   *
   *      This library is distributed in the hope that it will be useful,
   *      but WITHOUT ANY WARRANTY; without even the implied warranty of
   *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   *      Lesser General Public License for more details.
   *
   *      You should have received a copy of the GNU Lesser General Public
   *      License along with this library in the file COPYING.LIB;
   *      if not, write to the Free Software Foundation, Inc.,
   *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
   */
  
  
  #include <pthread.h>
  #include "implement.h"
  
  
  int
  pthread_spin_trylock (pthread_spinlock_t * lock)
  {
    register pthread_spinlock_t s;
  
    if (NULL == lock || NULL == *lock)
      {
        return (EINVAL);
      }
  
    if (*lock == PTHREAD_SPINLOCK_INITIALIZER)
      {
        int result;
  
        if ((result = pte_spinlock_check_need_init (lock)) != 0)
          {
            return (result);
          }
      }
  
    s = *lock;
  
    switch ((long)
            PTE_ATOMIC_COMPARE_EXCHANGE (&(s->interlock),
                                         PTE_SPIN_LOCKED,
                                         PTE_SPIN_UNLOCKED))
      {
      case PTE_SPIN_UNLOCKED:
        return 0;
      case PTE_SPIN_LOCKED:
        return EBUSY;
      case PTE_SPIN_USE_MUTEX:
        return pthread_mutex_trylock (&(s->u.mutex));
      }
  
    return EINVAL;
  }
  