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/*
* Copyright (C) 2007, 2008, 2010 Apple Inc. All rights reserved.
* Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com)
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*
* Note: The implementations of InterlockedIncrement and InterlockedDecrement are based
* on atomic_increment and atomic_exchange_and_add from the Boost C++ Library. The license
* is virtually identical to the Apple license above but is included here for completeness.
*
* Boost Software License - Version 1.0 - August 17th, 2003
*
* Permission is hereby granted, free of charge, to any person or organization
* obtaining a copy of the software and accompanying documentation covered by
* this license (the "Software") to use, reproduce, display, distribute,
* execute, and transmit the Software, and to prepare derivative works of the
* Software, and to permit third-parties to whom the Software is furnished to
* do so, all subject to the following:
*
* The copyright notices in the Software and this entire statement, including
* the above license grant, this restriction and the following disclaimer,
* must be included in all copies of the Software, in whole or in part, and
* all derivative works of the Software, unless such copies or derivative
* works are solely in the form of machine-executable object code generated by
* a source language processor.
*
* 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, TITLE AND NON-INFRINGEMENT. IN NO EVENT
* SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
* FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#ifndef Atomics_h
#define Atomics_h
#include <wtf/Platform.h>
#include <wtf/StdLibExtras.h>
#include <wtf/UnusedParam.h>
#if OS(WINDOWS)
#include <windows.h>
#elif OS(DARWIN)
#include <libkern/OSAtomic.h>
#elif OS(QNX)
#include <atomic.h>
#elif OS(ANDROID)
#include <sys/atomics.h>
#elif COMPILER(GCC)
#if (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 2))
#include <ext/atomicity.h>
#else
#include <bits/atomicity.h>
#endif
#endif
namespace WTF {
#if OS(WINDOWS)
#define WTF_USE_LOCKFREE_THREADSAFEREFCOUNTED 1
#if COMPILER(MINGW) || COMPILER(MSVC7_OR_LOWER) || OS(WINCE)
inline int atomicIncrement(int* addend) { return InterlockedIncrement(reinterpret_cast<long*>(addend)); }
inline int atomicDecrement(int* addend) { return InterlockedDecrement(reinterpret_cast<long*>(addend)); }
#else
inline int atomicIncrement(int volatile* addend) { return InterlockedIncrement(reinterpret_cast<long volatile*>(addend)); }
inline int atomicDecrement(int volatile* addend) { return InterlockedDecrement(reinterpret_cast<long volatile*>(addend)); }
#endif
#elif OS(DARWIN)
#define WTF_USE_LOCKFREE_THREADSAFEREFCOUNTED 1
inline int atomicIncrement(int volatile* addend) { return OSAtomicIncrement32Barrier(const_cast<int*>(addend)); }
inline int atomicDecrement(int volatile* addend) { return OSAtomicDecrement32Barrier(const_cast<int*>(addend)); }
#elif OS(QNX)
#define WTF_USE_LOCKFREE_THREADSAFEREFCOUNTED 1
// Note, atomic_{add, sub}_value() return the previous value of addend's content.
inline int atomicIncrement(int volatile* addend) { return static_cast<int>(atomic_add_value(reinterpret_cast<unsigned volatile*>(addend), 1)) + 1; }
inline int atomicDecrement(int volatile* addend) { return static_cast<int>(atomic_sub_value(reinterpret_cast<unsigned volatile*>(addend), 1)) - 1; }
#elif OS(ANDROID)
inline int atomicIncrement(int volatile* addend) { return __atomic_inc(addend); }
inline int atomicDecrement(int volatile* addend) { return __atomic_dec(addend); }
#elif COMPILER(GCC) && !CPU(SPARC64) // sizeof(_Atomic_word) != sizeof(int) on sparc64 gcc
#define WTF_USE_LOCKFREE_THREADSAFEREFCOUNTED 1
inline int atomicIncrement(int volatile* addend) { return __gnu_cxx::__exchange_and_add(addend, 1) + 1; }
inline int atomicDecrement(int volatile* addend) { return __gnu_cxx::__exchange_and_add(addend, -1) - 1; }
#endif
#if OS(WINDOWS)
inline bool weakCompareAndSwap(volatile unsigned* location, unsigned expected, unsigned newValue)
{
return InterlockedCompareExchange(reinterpret_cast<LONG volatile*>(location), static_cast<LONG>(newValue), static_cast<LONG>(expected)) == static_cast<LONG>(expected);
}
inline bool weakCompareAndSwap(void*volatile* location, void* expected, void* newValue)
{
return InterlockedCompareExchangePointer(location, newValue, expected) == expected;
}
#else // OS(WINDOWS) --> not windows
#if COMPILER(GCC) && !COMPILER(CLANG) // Work around a gcc bug
inline bool weakCompareAndSwap(volatile unsigned* location, unsigned expected, unsigned newValue)
#else
inline bool weakCompareAndSwap(unsigned* location, unsigned expected, unsigned newValue)
#endif
{
#if ENABLE(COMPARE_AND_SWAP)
bool result;
#if CPU(X86) || CPU(X86_64)
asm volatile(
"lock; cmpxchgl %3, %2\n\t"
"sete %1"
: "+a"(expected), "=q"(result), "+m"(*location)
: "r"(newValue)
: "memory"
);
#elif CPU(ARM_THUMB2)
unsigned tmp;
asm volatile(
"movw %1, #1\n\t"
"ldrex %2, %0\n\t"
"cmp %3, %2\n\t"
"bne.n 0f\n\t"
"strex %1, %4, %0\n\t"
"0:"
: "+m"(*location), "=&r"(result), "=&r"(tmp)
: "r"(expected), "r"(newValue)
: "memory");
result = !result;
#else
#error "Bad architecture for compare and swap."
#endif
return result;
#else
UNUSED_PARAM(location);
UNUSED_PARAM(expected);
UNUSED_PARAM(newValue);
CRASH();
return 0;
#endif
}
inline bool weakCompareAndSwap(void*volatile* location, void* expected, void* newValue)
{
#if ENABLE(COMPARE_AND_SWAP)
#if CPU(X86_64)
bool result;
asm volatile(
"lock; cmpxchgq %3, %2\n\t"
"sete %1"
: "+a"(expected), "=q"(result), "+m"(*location)
: "r"(newValue)
: "memory"
);
return result;
#else
return weakCompareAndSwap(bitwise_cast<unsigned*>(location), bitwise_cast<unsigned>(expected), bitwise_cast<unsigned>(newValue));
#endif
#else // ENABLE(COMPARE_AND_SWAP)
UNUSED_PARAM(location);
UNUSED_PARAM(expected);
UNUSED_PARAM(newValue);
CRASH();
return 0;
#endif // ENABLE(COMPARE_AND_SWAP)
}
#endif // OS(WINDOWS) (end of the not-windows case)
inline bool weakCompareAndSwapUIntPtr(volatile uintptr_t* location, uintptr_t expected, uintptr_t newValue)
{
return weakCompareAndSwap(reinterpret_cast<void*volatile*>(location), reinterpret_cast<void*>(expected), reinterpret_cast<void*>(newValue));
}
} // namespace WTF
#if USE(LOCKFREE_THREADSAFEREFCOUNTED)
using WTF::atomicDecrement;
using WTF::atomicIncrement;
#endif
#endif // Atomics_h
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