/*

 * Copyright (c) 2016, Alliance for Open Media. All rights reserved

 *

 * This source code is subject to the terms of the BSD 2 Clause License and

 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License

 * was not distributed with this source code in the LICENSE file, you can

 * obtain it at www.aomedia.org/license/software. If the Alliance for Open

 * Media Patent License 1.0 was not distributed with this source code in the

 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.

 */

#ifndef AOM_AOM_PORTS_AOM_ONCE_H_

#define AOM_AOM_PORTS_AOM_ONCE_H_

#include "config/aom_config.h"

/* Implement a function wrapper to guarantee initialization

 * thread-safety for library singletons.

 *

 * NOTE: This function uses static locks, and can only be

 * used with one common argument per compilation unit. So

 *

 * file1.c:

 *   aom_once(foo);

 *   ...

 *   aom_once(foo);

 *

 * file2.c:

 *   aom_once(bar);

 *

 * will ensure foo() and bar() are each called only once, but in

 *

 * file1.c:

 *   aom_once(foo);

 *   aom_once(bar):

 *

 * bar() will never be called because the lock is used up

 * by the call to foo().

 */

#if CONFIG_MULTITHREAD && defined(_WIN32)

#include <windows.h>

/* Declare a per-compilation-unit state variable to track the progress

 * of calling func() only once. This must be at global scope because

 * local initializers are not thread-safe in MSVC prior to Visual

 * Studio 2015.

 */

static INIT_ONCE aom_init_once = INIT_ONCE_STATIC_INIT;

static void aom_once(void (*func)(void)) {

  BOOL pending;

  InitOnceBeginInitialize(&aom_init_once, 0, &pending, NULL);

  if (!pending) {

    // Initialization has already completed.

    return;

  }

  func();

  InitOnceComplete(&aom_init_once, 0, NULL);

}

#elif CONFIG_MULTITHREAD && defined(__OS2__)

#define INCL_DOS

#include <os2.h>

static void aom_once(void (*func)(void)) {

  static volatile int done;

  /* If the initialization is complete, return early. */

  if (done) return;

  /* Causes all other threads in the process to block themselves

   * and give up their time slice.

   */

  DosEnterCritSec();

  if (!done) {

    func();

    done = 1;

  }

  /* Restores normal thread dispatching for the current process. */

  DosExitCritSec();

}

#elif CONFIG_MULTITHREAD && HAVE_PTHREAD_H

#include <pthread.h>

static void aom_once(void (*func)(void)) {

  static pthread_once_t lock = PTHREAD_ONCE_INIT;

  pthread_once(&lock, func);

}

decoder.c:aom_once

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static void aom_once(void (*func)(void)) {

87

1.98k

  static pthread_once_t lock = PTHREAD_ONCE_INIT;

88

1.98k

  pthread_once(&lock, func);

89

1.98k

}

encoder.c:aom_once

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86

1.26k

static void aom_once(void (*func)(void)) {

87

1.26k

  static pthread_once_t lock = PTHREAD_ONCE_INIT;

88

1.26k

  pthread_once(&lock, func);

89

1.26k

}

aom_dsp_rtcd.c:aom_once

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86

2

static void aom_once(void (*func)(void)) {

87

2

  static pthread_once_t lock = PTHREAD_ONCE_INIT;

88

2

  pthread_once(&lock, func);

89

2

}

aom_scale_rtcd.c:aom_once

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86

2

static void aom_once(void (*func)(void)) {

87

2

  static pthread_once_t lock = PTHREAD_ONCE_INIT;

88

2

  pthread_once(&lock, func);

89

2

}

av1_rtcd.c:aom_once

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86

2

static void aom_once(void (*func)(void)) {

87

2

  static pthread_once_t lock = PTHREAD_ONCE_INIT;

88

2

  pthread_once(&lock, func);

89

2

}

reconintra.c:aom_once

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86

2

static void aom_once(void (*func)(void)) {

87

2

  static pthread_once_t lock = PTHREAD_ONCE_INIT;

88

2

  pthread_once(&lock, func);

89

2

}

#else

/* Default version that performs no synchronization. */

static void aom_once(void (*func)(void)) {

  static volatile int done;

  if (!done) {

    func();

    done = 1;

  }

}

#endif

#endif  // AOM_AOM_PORTS_AOM_ONCE_H_