/*
  * Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
  *

  * This file is part of FFmpeg.

  *

  * FFmpeg 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 2.1 of the License, or (at your option) any later version.
  *

  * FFmpeg 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 FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 

 #include "config.h"

 #include "atomic.h"
 

 #if !HAVE_ATOMICS_NATIVE

 
 #if HAVE_PTHREADS
 
 #include <pthread.h>
 
 static pthread_mutex_t atomic_lock = PTHREAD_MUTEX_INITIALIZER;
 
 int avpriv_atomic_int_get(volatile int *ptr)
 {
     int res;
 
     pthread_mutex_lock(&atomic_lock);
     res = *ptr;
     pthread_mutex_unlock(&atomic_lock);
 
     return res;
 }
 
 void avpriv_atomic_int_set(volatile int *ptr, int val)
 {
     pthread_mutex_lock(&atomic_lock);
     *ptr = val;
     pthread_mutex_unlock(&atomic_lock);
 }
 
 int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc)
 {
     int res;
 
     pthread_mutex_lock(&atomic_lock);
     *ptr += inc;
     res = *ptr;
     pthread_mutex_unlock(&atomic_lock);
 
     return res;
 }
 
 void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval)
 {
     void *ret;
     pthread_mutex_lock(&atomic_lock);
     ret = *ptr;
     if (*ptr == oldval)
         *ptr = newval;
     pthread_mutex_unlock(&atomic_lock);
     return ret;
 }
 
 #elif !HAVE_THREADS
 
 int avpriv_atomic_int_get(volatile int *ptr)
 {
     return *ptr;
 }
 
 void avpriv_atomic_int_set(volatile int *ptr, int val)
 {
     *ptr = val;
 }
 
 int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc)
 {
     *ptr += inc;
     return *ptr;
 }
 
 void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval)
 {
     if (*ptr == oldval) {
         *ptr = newval;
         return oldval;
     }
     return *ptr;
 }
 

 #else /* HAVE_THREADS */

 /* This should never trigger, unless a new threading implementation
  * without correct atomics dependencies in configure or a corresponding
  * atomics implementation is added. */

 #error "Threading is enabled, but there is no implementation of atomic operations available"
 
 #endif /* HAVE_PTHREADS */
 

 #endif /* !HAVE_ATOMICS_NATIVE */

 
 #ifdef TEST

 #include "avassert.h"

 
 int main(void)
 {
     volatile int val = 1;
     int res;
 
     res = avpriv_atomic_int_add_and_fetch(&val, 1);

     av_assert0(res == 2);

     avpriv_atomic_int_set(&val, 3);
     res = avpriv_atomic_int_get(&val);

     av_assert0(res == 3);

 
     return 0;
 }
 #endif