heap/CopiedBlock.h

   1 /*
   2  * Copyright (C) 2011 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 CopiedBlock_h
  27 #define CopiedBlock_h
  28
  29 #include "HeapBlock.h"
  30 #include "JSValue.h"
  31 #include "JSValueInlineMethods.h"
  32
  33 namespace JSC {
  34
  35 class CopiedSpace;
  36
  37 class CopiedBlock : public HeapBlock {
  38     friend class CopiedSpace;
  39     friend class CopiedAllocator;
  40 public:
  41     CopiedBlock(PageAllocationAligned& allocation)
  42         : HeapBlock(allocation)
  43         , m_offset(payload())
  44         , m_isPinned(false)
  45     {
  46         ASSERT(is8ByteAligned(static_cast<void*>(m_offset)));
  47 #if USE(JSVALUE64)
  48         char* offset = static_cast<char*>(m_offset);
  49         memset(static_cast<void*>(offset), 0, static_cast<size_t>((reinterpret_cast<char*>(this) + allocation.size()) - offset));
  50 #else
  51         JSValue emptyValue;
  52         JSValue* limit = reinterpret_cast_ptr<JSValue*>(reinterpret_cast<char*>(this) + allocation.size());
  53         for (JSValue* currentValue = reinterpret_cast<JSValue*>(m_offset); currentValue < limit; currentValue++)
  54             *currentValue = emptyValue;
  55 #endif
  56     }
  57
  58     char* payload();
  59     size_t size();
  60     size_t capacity();
  61
  62 private:
  63     void* m_offset;
  64     uintptr_t m_isPinned;
  65 };
  66
  67 inline char* CopiedBlock::payload()
  68 {
  69     return reinterpret_cast<char*>(this) + ((sizeof(CopiedBlock) + 7) & ~7);
  70 }
  71
  72 inline size_t CopiedBlock::size()
  73 {
  74     return static_cast<size_t>(static_cast<char*>(m_offset) - payload());
  75 }
  76
  77 inline size_t CopiedBlock::capacity()
  78 {
  79     return m_allocation.size();
  80 }
  81
  82 } // namespace JSC
  83
  84 #endif