wtf/PageBlock.h

   1 /*
   2  * Copyright (C) 2010 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. AND ITS CONTRIBUTORS ``AS IS''
  14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  23  * THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef PageBlock_h
  27 #define PageBlock_h
  28
  29 namespace WTF {
  30
  31 size_t pageSize();
  32 inline bool isPageAligned(void* address) { return !(reinterpret_cast<intptr_t>(address) & (pageSize() - 1)); }
  33 inline bool isPageAligned(size_t size) { return !(size & (pageSize() - 1)); }
  34 inline bool isPowerOfTwo(size_t size) { return !(size & (size - 1)); }
  35
  36 class PageBlock {
  37 public:
  38     PageBlock();
  39     PageBlock(const PageBlock&);
  40     PageBlock(void*, size_t, bool hasGuardPages);
  41
  42     void* base() const { return m_base; }
  43     size_t size() const { return m_size; }
  44
  45     operator bool() const { return !!m_realBase; }
  46
  47     bool contains(void* containedBase, size_t containedSize)
  48     {
  49         return containedBase >= m_base
  50             && (static_cast<char*>(containedBase) + containedSize) <= (static_cast<char*>(m_base) + m_size);
  51     }
  52
  53 private:
  54     void* m_realBase;
  55     void* m_base;
  56     size_t m_size;
  57 };
  58
  59 inline PageBlock::PageBlock()
  60     : m_realBase(0)
  61     , m_base(0)
  62     , m_size(0)
  63 {
  64 }
  65
  66 inline PageBlock::PageBlock(const PageBlock& other)
  67     : m_realBase(other.m_realBase)
  68     , m_base(other.m_base)
  69     , m_size(other.m_size)
  70 {
  71 }
  72
  73 inline PageBlock::PageBlock(void* base, size_t size, bool hasGuardPages)
  74     : m_realBase(base)
  75     , m_base(static_cast<char*>(base) + ((base && hasGuardPages) ? pageSize() : 0))
  76     , m_size(size)
  77 {
  78 }
  79
  80 } // namespace WTF
  81
  82 using WTF::pageSize;
  83 using WTF::isPageAligned;
  84 using WTF::isPageAligned;
  85 using WTF::isPowerOfTwo;
  86
  87 #endif // PageBlock_h