mirror of
https://github.com/darlinghq/darling-JavaScriptCore.git
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107 lines
3.3 KiB
C++
107 lines
3.3 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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#if ENABLE(WEBASSEMBLY)
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#include <limits.h>
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namespace WTF {
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class PrintStream;
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}
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namespace JSC { namespace Wasm {
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class PageCount {
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public:
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PageCount()
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: m_pageCount(UINT_MAX)
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{
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static_assert(maxPageCount < UINT_MAX, "We rely on this here.");
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}
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PageCount(uint32_t pageCount)
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: m_pageCount(pageCount)
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{ }
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void dump(WTF::PrintStream&) const;
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uint64_t bytes() const { return static_cast<uint64_t>(m_pageCount) * static_cast<uint64_t>(pageSize); }
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uint32_t pageCount() const { return m_pageCount; }
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static bool isValid(uint32_t pageCount)
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{
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return pageCount <= maxPageCount;
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}
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bool isValid() const
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{
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return isValid(m_pageCount);
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}
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static PageCount fromBytes(uint64_t bytes)
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{
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RELEASE_ASSERT(bytes % pageSize == 0);
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uint32_t numPages = bytes / pageSize;
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RELEASE_ASSERT(PageCount::isValid(numPages));
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return PageCount(numPages);
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}
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static PageCount max()
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{
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return PageCount(maxPageCount);
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}
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explicit operator bool() const
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{
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return m_pageCount != UINT_MAX;
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}
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bool operator<(const PageCount& other) const { return m_pageCount < other.m_pageCount; }
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bool operator>(const PageCount& other) const { return m_pageCount > other.m_pageCount; }
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bool operator>=(const PageCount& other) const { return m_pageCount >= other.m_pageCount; }
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PageCount operator+(const PageCount& other) const
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{
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if (sumOverflows<uint32_t>(m_pageCount, other.m_pageCount))
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return PageCount();
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uint32_t newCount = m_pageCount + other.m_pageCount;
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if (!PageCount::isValid(newCount))
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return PageCount();
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return PageCount(newCount);
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}
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static constexpr uint32_t pageSize = 64 * KB;
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private:
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static constexpr uint32_t maxPageCount = static_cast<uint32_t>((1ull << 32) / pageSize);
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uint32_t m_pageCount;
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};
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} } // namespace JSC::Wasm
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#endif // ENABLE(WEBASSEMBLY)
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