103 lines
3.0 KiB
C++
103 lines
3.0 KiB
C++
// vim: set sts=8 ts=2 sw=2 tw=99 et:
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//
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// Copyright (C) 2013, David Anderson and AlliedModders LLC
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice, this
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// list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of AlliedModders LLC nor the names of its contributors
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// may be used to endorse or promote products derived from this software
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// without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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#ifndef _include_amtl_atomics_h_
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#define _include_amtl_atomics_h_
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#include <am-utility.h>
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namespace ke {
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#if defined(_MSC_VER)
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extern "C" {
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long __cdecl _InterlockedIncrement(long volatile *dest);
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long __cdecl _InterlockedDecrement(long volatile *dest);
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}
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# pragma intrinsic(_InterlockedIncrement)
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# pragma intrinsic(_InterlockedDecrement)
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#endif
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template <size_t Width>
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struct AtomicOps;
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template <>
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struct AtomicOps<4>
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{
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#if defined(_MSC_VER)
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typedef long Type;
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static Type Increment(Type *ptr) {
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return _InterlockedIncrement(ptr);
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}
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static Type Decrement(Type *ptr) {
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return _InterlockedDecrement(ptr);
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};
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#elif defined(__GNUC__)
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typedef int Type;
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// x86/x64 notes: When using GCC < 4.8, this will compile to a spinlock.
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// On 4.8+, or when using Clang, we'll get the more optimal "lock addl"
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// variant.
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static Type Increment(Type *ptr) {
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return __sync_add_and_fetch(ptr, 1);
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}
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static Type Decrement(Type *ptr) {
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return __sync_sub_and_fetch(ptr, 1);
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}
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#endif
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};
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class AtomicRefCount
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{
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typedef AtomicOps<sizeof(uintptr_t)> Ops;
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public:
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AtomicRefCount(uintptr_t value)
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: value_(value)
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{
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}
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void increment() {
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Ops::Increment(&value_);
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}
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// Return false if all references are gone.
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bool decrement() {
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return Ops::Decrement(&value_) != 0;
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}
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private:
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Ops::Type value_;
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};
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}
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#endif // _include_amtl_atomics_h_
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