/* * pthread_spin_trylock.c * * Description: * This translation unit implements spin lock primitives. * * -------------------------------------------------------------------------- * *      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 current list of contributors is contained *      in the file CONTRIBUTORS 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"intpthread_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 = ptw32_spinlock_check_need_init (lock)) != 0)	{	  return (result);	}    }  s = *lock;  switch ((long)	  PTW32_INTERLOCKED_COMPARE_EXCHANGE ((PTW32_INTERLOCKED_LPLONG) &					      (s->interlock),					      (PTW32_INTERLOCKED_LONG)					      PTW32_SPIN_LOCKED,					      (PTW32_INTERLOCKED_LONG)					      PTW32_SPIN_UNLOCKED))    {    case PTW32_SPIN_UNLOCKED:      return 0;    case PTW32_SPIN_LOCKED:      return EBUSY;    case PTW32_SPIN_USE_MUTEX:      return pthread_mutex_trylock (&(s->u.mutex));    }  return EINVAL;}