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/*
* Copyright (C) 2016 Apple Inc. All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 INC. OR
* 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.
*/
#pragma once
#if ENABLE(WEBASSEMBLY)
#include <limits.h>
namespace WTF {
class PrintStream;
}
namespace JSC { namespace Wasm {
class PageCount {
public:
PageCount()
: m_pageCount(UINT_MAX)
{
static_assert(maxPageCount < UINT_MAX, "We rely on this here.");
}
PageCount(uint32_t pageCount)
: m_pageCount(pageCount)
{ }
void dump(WTF::PrintStream&) const;
uint64_t bytes() const { return static_cast<uint64_t>(m_pageCount) * static_cast<uint64_t>(pageSize); }
uint32_t pageCount() const { return m_pageCount; }
static bool isValid(uint32_t pageCount)
{
return pageCount <= maxPageCount;
}
static PageCount fromBytes(uint64_t bytes)
{
RELEASE_ASSERT(bytes % pageSize == 0);
uint32_t numPages = bytes / pageSize;
RELEASE_ASSERT(PageCount::isValid(numPages));
return PageCount(numPages);
}
static PageCount max()
{
return PageCount(maxPageCount);
}
explicit operator bool() const
{
return m_pageCount != UINT_MAX;
}
bool operator<(const PageCount& other) const { return m_pageCount < other.m_pageCount; }
bool operator>(const PageCount& other) const { return m_pageCount > other.m_pageCount; }
bool operator>=(const PageCount& other) const { return m_pageCount >= other.m_pageCount; }
PageCount operator+(const PageCount& other) const
{
if (sumOverflows<uint32_t>(m_pageCount, other.m_pageCount))
return PageCount();
uint32_t newCount = m_pageCount + other.m_pageCount;
if (!PageCount::isValid(newCount))
return PageCount();
return PageCount(newCount);
}
static constexpr uint32_t pageSize = 64 * KB;
private:
static constexpr uint32_t maxPageCount = static_cast<uint32_t>((1ull << 32) / pageSize);
uint32_t m_pageCount;
};
} } // namespace JSC::Wasm
#endif // ENABLE(WASM)
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