liballjoyn-common-dev-1604 16.04a-3 / usr / include / x86_64-linux-gnu / qcc / posix / atomic.h

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

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 * Copyright 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.
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 *    THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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#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 its 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 its 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;
}

/**
 * Performs an atomic compare-and-exchange operation on the specified values.
 * It compares two specified 32-bit values and exchanges with another 32-bit
 * value based on the outcome of the comparison.
 *
 * @param mem  Pointer to int32_t to be compared and modified.
 * @param  expectedValue Expected value of *mem.
 * @param  newValue New value of *mem after calling this function, if returning true.
 * @return  true if the initial value of *mem was expectedValue, false otherwise
 */
inline bool CompareAndExchange(volatile int32_t* mem, int32_t expectedValue, int32_t newValue)
{
    /* Use strong memory ordering model */
    return __atomic_compare_exchange_n(mem, &expectedValue, newValue, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
}

/**
 * Performs an atomic compare-and-exchange operation on the specified pointer values.
 * It compares two specified pointer values and exchanges with another pointer
 * value based on the outcome of the comparison.
 *
 * @param mem  Pointer to the pointer value to be compared and modified.
 * @param expectedValue  Expected value of *mem.
 * @param newValue  New value of *mem after calling this function, if returning true.
 * @return  true if the initial value of *mem was expectedValue, false otherwise
 */
inline bool CompareAndExchangePointer(void* volatile* mem, void* expectedValue, void* newValue)
{
    /* Use strong memory ordering model */
    return __atomic_compare_exchange_n(mem, &expectedValue, newValue, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
}

#elif defined(QCC_OS_LINUX)

/**
 * Increment an int32_t and return its 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 its 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);
}

/**
 * Performs an atomic compare-and-exchange operation on the specified values.
 * It compares two specified 32-bit values and exchanges with another 32-bit
 * value based on the outcome of the comparison.
 *
 * @param mem  Pointer to int32_t to be compared and modified.
 * @param expectedValue  Expected value of *mem.
 * @param newValue  New value of *mem after calling this function, if returning true.
 * @return  true if the initial value of *mem was expectedValue, false otherwise
 */
inline bool CompareAndExchange(volatile int32_t* mem, int32_t expectedValue, int32_t newValue) {
    return __sync_bool_compare_and_swap(mem, expectedValue, newValue);
}

/**
 * Performs an atomic compare-and-exchange operation on the specified pointer values.
 * It compares two specified pointer values and exchanges with another pointer
 * value based on the outcome of the comparison.
 *
 * @param mem  Pointer to the pointer value to be compared and modified.
 * @param expectedValue  Expected value of *mem.
 * @param newValue  New value of *mem after calling this function, if returning true.
 * @return  true if the initial value of *mem was expectedValue, false otherwise
 */
inline bool CompareAndExchangePointer(void* volatile* mem, void* expectedValue, void* newValue) {
    return __sync_bool_compare_and_swap(mem, expectedValue, newValue);
}

#elif defined(QCC_OS_DARWIN)

/**
 * Increment an int32_t and return its 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 its 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);
}

/**
 * Performs an atomic compare-and-exchange operation on the specified values.
 * It compares two specified 32-bit values and exchanges with another 32-bit
 * value based on the outcome of the comparison.
 *
 * @param mem  Pointer to int32_t to be compared and modified.
 * @param expectedValue  Expected value of *mem.
 * @param newValue  New value of *mem after calling this function, if returning true.
 * @return  true if the initial value of *mem was expectedValue, false otherwise
 */
inline bool CompareAndExchange(volatile int32_t* mem, int32_t expectedValue, int32_t newValue) {
    return OSAtomicCompareAndSwapIntBarrier(expectedValue, newValue, mem);
}

/**
 * Performs an atomic compare-and-exchange operation on the specified pointer values.
 * It compares two specified pointer values and exchanges with another pointer
 * value based on the outcome of the comparison.
 *
 * @param mem  Pointer to the pointer value to be compared and modified.
 * @param expectedValue  Expected value of *mem.
 * @param newValue  New value of *mem after calling this function, if returning true.
 * @return  true if the initial value of *mem was expectedValue, false otherwise
 */
inline bool CompareAndExchangePointer(void* volatile* mem, void* expectedValue, void* newValue) {
    return OSAtomicCompareAndSwapPtrBarrier(expectedValue, newValue, mem);
}

#else

/**
 * Increment an int32_t and return its 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 its 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);

/**
 * Performs an atomic compare-and-exchange operation on the specified values.
 * It compares two specified 32-bit values and exchanges with another 32-bit
 * value based on the outcome of the comparison.
 *
 * @param mem  Pointer to int32_t to be compared and modified.
 * @param expectedValue  Expected value of *mem.
 * @param newValue  New value of *mem after calling this function, if returning true.
 * @return  true if the initial value of *mem was expectedValue, false otherwise
 */
bool CompareAndExchange(volatile int32_t* mem, int32_t expectedValue, int32_t newValue);

/**
 * Performs an atomic compare-and-exchange operation on the specified pointer values.
 * It compares two specified pointer values and exchanges with another pointer
 * value based on the outcome of the comparison.
 *
 * @param mem  Pointer to the pointer value to be compared and modified.
 * @param expectedValue  Expected value of *mem.
 * @param newValue  New value of *mem after calling this function, if returning true.
 * @return  true if the initial value of *mem was expectedValue, false otherwise
 */
bool CompareAndExchangePointer(void* volatile* mem, void* expectedValue, void* newValue);

#endif

}

#endif