/* -*- C -*-

// -------------------------------------------------------------------

// Atomic primitives

// Copyright (c) 2008  Leon Bottou. All rights reserved

//

// Permission is hereby granted, free of charge, to any person obtaining

// a copy of this software and associated documentation files (the

// "Software"), to deal in the Software without restriction, including

// without limitation the rights to use, copy, modify, merge, publish,

// distribute, sublicense, and/or sell copies of the Software, and to

// permit persons to whom the Software is furnished to do so, subject to

// the following conditions:

//

// The above copyright notice and this permission notice shall be

// included in all copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY

// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,

// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

//

// ------------------------------------------------------------------- */

#include "atomic.h"

#ifndef ATOMIC_MACROS

#if HAVE_PTHREAD

# include <pthread.h>

#elif HAVE_QTHREAD  // never defined at the moment.

# include <QMutex>

# include <QWaitCondition>

#else

# include "GThreads.h"

#endif

/* Select synchronization primitives */

# if defined(_WIN32) || defined(_WIN64)

namespace {

  struct CS { 

    CRITICAL_SECTION cs; 

    CS() { InitializeCriticalSection(&cs); }

    ~CS() { DeleteCriticalSecton(&cs); } }; }

static CS globalCS;

# define MUTEX_LEAVE LeaveCriticalSection(&globalCS.cs)

# define MUTEX_ENTER EnterCriticalSection(&globalCS.cs);

# elif defined (PTHREAD_MUTEX_INITIALIZER)

static pthread_mutex_t ptm = PTHREAD_MUTEX_INITIALIZER;

# define MUTEX_ENTER  pthread_mutex_lock(&ptm)

# define MUTEX_LEAVE  pthread_mutex_unlock(&ptm)

# elif defined(__cplusplus) && defined(_GTHREADS_H_)

static GMonitor m;

# define MUTEX_ENTER  m.enter()

# define MUTEX_LEAVE  m.leave()

# elif defined(__cplusplus) && defined(QMUTEX_H)

static QMutex qtm;

# define MUTEX_ENTER  qtm.lock()

# define MUTEX_LEAVE  qtm.unlock()

# endif

/* atomic primitive emulation */

int

atomicIncrement(int volatile *var)

{

  int res;

  MUTEX_ENTER;

  res = ++(*var);

  MUTEX_LEAVE;

  return res;

}

int 

atomicDecrement(int volatile *var)

{

  int res;

  MUTEX_ENTER;

  res = --(*var);

  MUTEX_LEAVE;

  return res;

}

int 

atomicCompareAndSwap(int volatile *var, int oldval, int newval)

{

  int ret;

  MUTEX_ENTER;

  ret = *var;

  if (ret == oldval)

    *var = newval;

  MUTEX_LEAVE;

  return ret;

}

int 

atomicExchange(int volatile *var, int newval)

{

  int ret;

  MUTEX_ENTER;

  ret = *var;

  *var = newval;

  MUTEX_LEAVE;

  return ret;

}

void* 

atomicExchangePointer(void* volatile *var, void* newval)

{

  void *ret;

  MUTEX_ENTER;

  ret = *var;

  *var = newval;

  MUTEX_LEAVE;

  return ret;

}

#endif