darling-bmalloc/bmalloc/IsoDirectoryPage.h
2020-08-28 09:14:52 -04:00

61 lines
2.3 KiB
C++

/*
* Copyright (C) 2017 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
#include "BMalloced.h"
#include "IsoDirectory.h"
namespace bmalloc {
template<typename Config>
class IsoDirectoryPage {
MAKE_BMALLOCED;
public:
// By my math, this results in an IsoDirectoryPage using 4036 bytes on 64-bit platforms. We allocate it
// with malloc, so it doesn't really matter how much memory it uses. But it's nice that this about a
// page, since that's quite intuitive.
//
// On 32-bit platforms, I think that this will be 2112 bytes. That's still quite intuitive.
//
// Note that this is a multiple of 32 so that it uses bitvectors efficiently.
static constexpr unsigned numPages = 480;
IsoDirectoryPage(IsoHeapImpl<Config>&, unsigned index);
static IsoDirectoryPage* pageFor(IsoDirectory<Config, numPages>* payload);
unsigned index() const { return m_index; }
IsoDirectory<Config, numPages> payload;
IsoDirectoryPage* next { nullptr };
private:
unsigned m_index;
};
} // namespace bmalloc