97 lines
3.0 KiB
C++
97 lines
3.0 KiB
C++
/*
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* Copyright (C) 2016-2017 Apple Inc. 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
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include "BExport.h"
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#include <cstddef>
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#include <cstdint>
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namespace bmalloc {
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class VariadicBumpAllocator;
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struct FreeCell {
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static uintptr_t scramble(FreeCell* cell, uintptr_t secret)
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{
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return reinterpret_cast<uintptr_t>(cell) ^ secret;
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}
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static FreeCell* descramble(uintptr_t cell, uintptr_t secret)
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{
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return reinterpret_cast<FreeCell*>(cell ^ secret);
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}
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void setNext(FreeCell* next, uintptr_t secret)
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{
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scrambledNext = scramble(next, secret);
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}
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FreeCell* next(uintptr_t secret) const
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{
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return descramble(scrambledNext, secret);
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}
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uintptr_t scrambledNext;
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};
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class FreeList {
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public:
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friend class VariadicBumpAllocator;
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BEXPORT FreeList();
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BEXPORT ~FreeList();
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BEXPORT void clear();
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BEXPORT void initializeList(FreeCell* head, uintptr_t secret, unsigned bytes);
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BEXPORT void initializeBump(char* payloadEnd, unsigned remaining);
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bool allocationWillFail() const { return !head() && !m_remaining; }
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bool allocationWillSucceed() const { return !allocationWillFail(); }
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template<typename Config, typename Func>
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void* allocate(const Func& slowPath);
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bool contains(void*) const;
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template<typename Config, typename Func>
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void forEach(const Func&) const;
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unsigned originalSize() const { return m_originalSize; }
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private:
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FreeCell* head() const { return FreeCell::descramble(m_scrambledHead, m_secret); }
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uintptr_t m_scrambledHead { 0 };
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uintptr_t m_secret { 0 };
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char* m_payloadEnd { nullptr };
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unsigned m_remaining { 0 };
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unsigned m_originalSize { 0 };
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};
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} // namespace bmalloc
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