third_party/WebKit/Source/wtf/Alignment.h

   1 /*
   2  *  Copyright (C) 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
   3  *
   4  *  This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  *  This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU Library General Public License
  15  *  along with this library; see the file COPYING.LIB.  If not, write to
  16  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  *  Boston, MA 02110-1301, USA.
  18  *
  19  */
  20
  21 #ifndef WTF_Alignment_h
  22 #define WTF_Alignment_h
  23
  24 #include <algorithm>
  25 #include <stdint.h>
  26 #include <utility>
  27
  28
  29 namespace WTF {
  30
  31 #if COMPILER(GCC)
  32     #define WTF_ALIGN_OF(type) __alignof__(type)
  33     #define WTF_ALIGNED(variable_type, variable, n) variable_type variable __attribute__((__aligned__(n)))
  34 #elif COMPILER(MSVC)
  35     #define WTF_ALIGN_OF(type) __alignof(type)
  36     #define WTF_ALIGNED(variable_type, variable, n) __declspec(align(n)) variable_type variable
  37 #else
  38     #error WTF_ALIGN macros need alignment control.
  39 #endif
  40
  41 #if COMPILER(GCC)
  42     typedef char __attribute__((__may_alias__)) AlignedBufferChar;
  43 #else
  44     typedef char AlignedBufferChar;
  45 #endif
  46
  47     template<size_t size, size_t alignment> struct AlignedBuffer;
  48     template<size_t size> struct AlignedBuffer<size, 1> { AlignedBufferChar buffer[size]; };
  49     template<size_t size> struct AlignedBuffer<size, 2> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 2);  };
  50     template<size_t size> struct AlignedBuffer<size, 4> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 4);  };
  51     template<size_t size> struct AlignedBuffer<size, 8> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 8);  };
  52     template<size_t size> struct AlignedBuffer<size, 16> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 16); };
  53     template<size_t size> struct AlignedBuffer<size, 32> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 32); };
  54     template<size_t size> struct AlignedBuffer<size, 64> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 64); };
  55
  56     template <size_t size, size_t alignment>
  57     void swap(AlignedBuffer<size, alignment>& a, AlignedBuffer<size, alignment>& b)
  58     {
  59         for (size_t i = 0; i < size; ++i)
  60             std::swap(a.buffer[i], b.buffer[i]);
  61     }
  62
  63     template <uintptr_t mask>
  64     inline bool isAlignedTo(const void* pointer)
  65     {
  66         return !(reinterpret_cast<uintptr_t>(pointer) & mask);
  67     }
  68 }
  69
  70 #endif // WTF_Alignment_h