1/*
2 * Copyright (C) 2014 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef XLargeChunk_h
27#define XLargeChunk_h
28
29#include "Sizes.h"
30
31namespace bmalloc {
32
33class XLargeChunk {
34public:
35    static XLargeChunk* create(size_t);
36    static void destroy(XLargeChunk*);
37
38    static XLargeChunk* get(void* object) { return reinterpret_cast<XLargeChunk*>(LargeChunk::get(object)); }
39
40    char* begin() { return m_largeChunk.begin(); }
41    size_t& size();
42
43private:
44    XLargeChunk(const Range&, size_t);
45    Range& range();
46
47    LargeChunk m_largeChunk;
48};
49
50inline XLargeChunk::XLargeChunk(const Range& range, size_t size)
51{
52    this->range() = range;
53    this->size() = size;
54}
55
56inline XLargeChunk* XLargeChunk::create(size_t size)
57{
58    size_t vmSize = bmalloc::vmSize(sizeof(XLargeChunk) + size);
59    std::pair<void*, Range> result = vmAllocate(vmSize, superChunkSize, largeChunkOffset);
60    return new (result.first) XLargeChunk(result.second, size);
61}
62
63inline void XLargeChunk::destroy(XLargeChunk* chunk)
64{
65    const Range& range = chunk->range();
66    vmDeallocate(range.begin(), range.size());
67}
68
69inline Range& XLargeChunk::range()
70{
71    // Since we hold only one object, we only use our first BoundaryTag. So, we
72    // can stuff our range into the remaining metadata.
73    Range& result = *reinterpret_cast<Range*>(roundUpToMultipleOf<alignment>(LargeChunk::beginTag(begin()) + 1));
74    BASSERT(static_cast<void*>(&result) < static_cast<void*>(begin()));
75    return result;
76}
77
78inline size_t& XLargeChunk::size()
79{
80    // Since we hold only one object, we only use our first BoundaryTag. So, we
81    // can stuff our size into the remaining metadata.
82    size_t& result = *reinterpret_cast<size_t*>(roundUpToMultipleOf<alignment>(&range() + 1));
83    BASSERT(static_cast<void*>(&result) < static_cast<void*>(begin()));
84    return result;
85}
86
87}; // namespace bmalloc
88
89#endif // XLargeChunk
90