relibc_pthreads-emb/pthread_spin_init.c

/*
 * pthread_spin_init.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 <stdlib.h>

#include "pthread.h"
#include "implement.h"


int
pthread_spin_init (pthread_spinlock_t * lock, int pshared)
{
  pthread_spinlock_t s;
  int cpus = 0;
  int result = 0;

  if (lock == NULL)
    {
      return EINVAL;
    }

  if (0 != pte_getprocessors (&cpus))
    {
      cpus = 1;
    }

  if (cpus > 1)
    {
      if (pshared == PTHREAD_PROCESS_SHARED)
        {
          /*
           * Creating spinlock that can be shared between
           * processes.
           */
#if _POSIX_THREAD_PROCESS_SHARED >= 0

          /*
           * Not implemented yet.
           */

#error ERROR [__FILE__, line __LINE__]: Process shared spin locks are not supported yet.

#else

          return ENOSYS;

#endif /* _POSIX_THREAD_PROCESS_SHARED */

        }
    }

  s = (pthread_spinlock_t) calloc (1, sizeof (*s));

  if (s == NULL)
    {
      return ENOMEM;
    }

  if (cpus > 1)
    {
      s->u.cpus = cpus;
      s->interlock = PTE_SPIN_UNLOCKED;
    }
  else
    {
      pthread_mutexattr_t ma;
      result = pthread_mutexattr_init (&ma);

      if (0 == result)
        {
          ma->pshared = pshared;
          result = pthread_mutex_init (&(s->u.mutex), &ma);
          if (0 == result)
            {
              s->interlock = PTE_SPIN_USE_MUTEX;
            }
        }
      (void) pthread_mutexattr_destroy (&ma);
    }

  if (0 == result)
    {
      *lock = s;
    }
  else
    {
      (void) free (s);
      *lock = NULL;
    }

  return (result);
}