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      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);
     41 
     42     void* base() const { return m_base; }
     43     size_t size() const { return m_size; }
     44 
     45     operator bool() const { return !!m_base; }
     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_base;
     55     size_t m_size;
     56 };
     57 
     58 inline PageBlock::PageBlock()
     59     : m_base(0)
     60     , m_size(0)
     61 {
     62 }
     63 
     64 inline PageBlock::PageBlock(const PageBlock& other)
     65     : m_base(other.m_base)
     66     , m_size(other.m_size)
     67 {
     68 }
     69 
     70 inline PageBlock::PageBlock(void* base, size_t size)
     71     : m_base(base)
     72     , m_size(size)
     73 {
     74 }
     75 
     76 } // namespace WTF
     77 
     78 using WTF::pageSize;
     79 using WTF::isPageAligned;
     80 using WTF::isPageAligned;
     81 using WTF::isPowerOfTwo;
     82 
     83 #endif // PageBlock_h
     84