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  1. /*
  2.  * Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
  3.  *
  4.  * This file is part of FFmpeg.
  5.  *
  6.  * FFmpeg is free software; you can redistribute it and/or
  7.  * modify it under the terms of the GNU Lesser General Public
  8.  * License as published by the Free Software Foundation; either
  9.  * version 2.1 of the License, or (at your option) any later version.
  10.  *
  11.  * FFmpeg is distributed in the hope that it will be useful,
  12.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14.  * Lesser General Public License for more details.
  15.  *
  16.  * You should have received a copy of the GNU Lesser General Public
  17.  * License along with FFmpeg; if not, write to the Free Software
  18.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19.  */
  20.  
  21. #include "atomic.h"
  22.  
  23. #if !HAVE_ATOMICS_NATIVE
  24.  
  25. #if HAVE_PTHREADS
  26.  
  27. #include <pthread.h>
  28.  
  29. static pthread_mutex_t atomic_lock = PTHREAD_MUTEX_INITIALIZER;
  30.  
  31. int avpriv_atomic_int_get(volatile int *ptr)
  32. {
  33.     int res;
  34.  
  35.     pthread_mutex_lock(&atomic_lock);
  36.     res = *ptr;
  37.     pthread_mutex_unlock(&atomic_lock);
  38.  
  39.     return res;
  40. }
  41.  
  42. void avpriv_atomic_int_set(volatile int *ptr, int val)
  43. {
  44.     pthread_mutex_lock(&atomic_lock);
  45.     *ptr = val;
  46.     pthread_mutex_unlock(&atomic_lock);
  47. }
  48.  
  49. int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc)
  50. {
  51.     int res;
  52.  
  53.     pthread_mutex_lock(&atomic_lock);
  54.     *ptr += inc;
  55.     res = *ptr;
  56.     pthread_mutex_unlock(&atomic_lock);
  57.  
  58.     return res;
  59. }
  60.  
  61. void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval)
  62. {
  63.     void *ret;
  64.     pthread_mutex_lock(&atomic_lock);
  65.     ret = *ptr;
  66.     if (*ptr == oldval)
  67.         *ptr = newval;
  68.     pthread_mutex_unlock(&atomic_lock);
  69.     return ret;
  70. }
  71.  
  72. #elif !HAVE_THREADS
  73.  
  74. int avpriv_atomic_int_get(volatile int *ptr)
  75. {
  76.     return *ptr;
  77. }
  78.  
  79. void avpriv_atomic_int_set(volatile int *ptr, int val)
  80. {
  81.     *ptr = val;
  82. }
  83.  
  84. int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc)
  85. {
  86.     *ptr += inc;
  87.     return *ptr;
  88. }
  89.  
  90. void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval)
  91. {
  92.     if (*ptr == oldval) {
  93.         *ptr = newval;
  94.         return oldval;
  95.     }
  96.     return *ptr;
  97. }
  98.  
  99. #else
  100.  
  101. #error "Threading is enabled, but there is no implementation of atomic operations available"
  102.  
  103. #endif /* HAVE_PTHREADS */
  104.  
  105. #endif /* !HAVE_MEMORYBARRIER && !HAVE_SYNC_VAL_COMPARE_AND_SWAP && !HAVE_MACHINE_RW_BARRIER */
  106.  
  107. #ifdef TEST
  108. #include "avassert.h"
  109.  
  110. int main(void)
  111. {
  112.     volatile int val = 1;
  113.     int res;
  114.  
  115.     res = avpriv_atomic_int_add_and_fetch(&val, 1);
  116.     av_assert0(res == 2);
  117.     avpriv_atomic_int_set(&val, 3);
  118.     res = avpriv_atomic_int_get(&val);
  119.     av_assert0(res == 3);
  120.  
  121.     return 0;
  122. }
  123. #endif
  124.