/**
 * @file
 *
 * Define atomic read-modify-write memory options
 */

/******************************************************************************
 *
 *
 * Copyright (c) 2009-2011, AllSeen Alliance. All rights reserved.
 *
 *    Permission to use, copy, modify, and/or distribute this software for any
 *    purpose with or without fee is hereby granted, provided that the above
 *    copyright notice and this permission notice appear in all copies.
 *
 *    THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *    WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *    MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *    ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *    ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 ******************************************************************************/
#ifndef _POSIX_QCC_ATOMIC_H
#define _POSIX_QCC_ATOMIC_H

#include <qcc/platform.h>

#ifdef QCC_OS_ANDROID
#include <sys/atomics.h>
#endif

#if defined(QCC_OS_DARWIN)
#include <libkern/OSAtomic.h>
#endif

namespace qcc {

#if defined(QCC_OS_ANDROID)

/**
 * Increment an int32_t and return it's new value atomically.
 *
 * @param mem   Pointer to int32_t to be incremented.
 * @return  New value (after increment) of *mem
 */
inline int32_t IncrementAndFetch(volatile int32_t* mem)
{
    /*
     * Androids built in __atomic_inc operation returns the previous value
     * stored in mem. This value has been changed in memory.  Since we expect
     * the value after the increment to be returned we add one to the value
     * returned by __atomic_inc.
     */
    return __atomic_inc(mem) + 1;
}

/**
 * Decrement an int32_t and return it's new value atomically.
 *
 * @param mem   Pointer to int32_t to be decremented.
 * @return  New value (after decrement) of *mem
 */
inline int32_t DecrementAndFetch(volatile int32_t* mem)
{
    /*
     * Androids built in __atomic_dec operation returns the previous value
     * stored in mem. This value has been changed in memory.  Since we expect
     * the value after the decrement to be returned we subtract one from the
     * value returned by __atomic_dec.
     */
    return __atomic_dec(mem) - 1;
}

#elif defined(QCC_OS_LINUX)

/**
 * Increment an int32_t and return it's new value atomically.
 *
 * @param mem   Pointer to int32_t to be incremented.
 * @return  New value (after increment) of *mem
 */
inline int32_t IncrementAndFetch(volatile int32_t* mem) {
    return __sync_add_and_fetch(mem, 1);
}

/**
 * Decrement an int32_t and return it's new value atomically.
 *
 * @param mem   Pointer to int32_t to be decremented.
 * @return  New value (afer decrement) of *mem
 */
inline int32_t DecrementAndFetch(volatile int32_t* mem) {
    return __sync_sub_and_fetch(mem, 1);
}

#elif defined(QCC_OS_DARWIN)

/**
 * Increment an int32_t and return it's new value atomically.
 *
 * @param mem   Pointer to int32_t to be incremented.
 * @return  New value (after increment) of *mem
 */
inline int32_t IncrementAndFetch(volatile int32_t* mem) {
    return OSAtomicIncrement32(mem);
}

/**
 * Decrement an int32_t and return it's new value atomically.
 *
 * @param mem   Pointer to int32_t to be decremented.
 * @return  New value (afer decrement) of *mem
 */
inline int32_t DecrementAndFetch(volatile int32_t* mem) {
    return OSAtomicDecrement32(mem);
}

#else

/**
 * Increment an int32_t and return it's new value atomically.
 *
 * @param mem   Pointer to int32_t to be incremented.
 * @return  New value (afer increment) of *mem
 */
int32_t IncrementAndFetch(volatile int32_t* mem);

/**
 * Decrement an int32_t and return it's new value atomically.
 *
 * @param mem   Pointer to int32_t to be decremented.
 * @return  New value (afer decrement) of *mem
 */
int32_t DecrementAndFetch(volatile int32_t* mem);

#endif

}

#endif