1/*
2 * Copyright (C) 2016-2017 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#pragma once
27
28#if ENABLE(WEBASSEMBLY)
29
30#include <limits.h>
31
32namespace WTF {
33class PrintStream;
34}
35
36namespace JSC { namespace Wasm {
37
38class PageCount {
39
40public:
41 PageCount()
42 : m_pageCount(UINT_MAX)
43 {
44 static_assert(maxPageCount < UINT_MAX, "We rely on this here.");
45 }
46
47 PageCount(uint32_t pageCount)
48 : m_pageCount(pageCount)
49 { }
50
51 void dump(WTF::PrintStream&) const;
52
53 uint64_t bytes() const { return static_cast<uint64_t>(m_pageCount) * static_cast<uint64_t>(pageSize); }
54 uint32_t pageCount() const { return m_pageCount; }
55
56 static bool isValid(uint32_t pageCount)
57 {
58 return pageCount <= maxPageCount;
59 }
60
61 bool isValid() const
62 {
63 return isValid(m_pageCount);
64 }
65
66 static PageCount fromBytes(uint64_t bytes)
67 {
68 RELEASE_ASSERT(bytes % pageSize == 0);
69 uint32_t numPages = bytes / pageSize;
70 RELEASE_ASSERT(PageCount::isValid(numPages));
71 return PageCount(numPages);
72 }
73
74 static PageCount max()
75 {
76 return PageCount(maxPageCount);
77 }
78
79 explicit operator bool() const
80 {
81 return m_pageCount != UINT_MAX;
82 }
83
84 bool operator<(const PageCount& other) const { return m_pageCount < other.m_pageCount; }
85 bool operator>(const PageCount& other) const { return m_pageCount > other.m_pageCount; }
86 bool operator>=(const PageCount& other) const { return m_pageCount >= other.m_pageCount; }
87 PageCount operator+(const PageCount& other) const
88 {
89 if (sumOverflows<uint32_t>(m_pageCount, other.m_pageCount))
90 return PageCount();
91 uint32_t newCount = m_pageCount + other.m_pageCount;
92 if (!PageCount::isValid(newCount))
93 return PageCount();
94 return PageCount(newCount);
95 }
96
97 static constexpr uint32_t pageSize = 64 * KB;
98private:
99 static constexpr uint32_t maxPageCount = static_cast<uint32_t>((1ull << 32) / pageSize);
100
101 uint32_t m_pageCount;
102};
103
104} } // namespace JSC::Wasm
105
106#endif // ENABLE(WEBASSEMBLY)
107