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 27 28 namespace WTF { 29 30 #if COMPILER(GCC) 31 #define WTF_ALIGN_OF(type) __alignof__(type) 32 #define WTF_ALIGNED(variable_type, variable, n) variable_type variable __attribute__((__aligned__(n))) 33 #elif COMPILER(MSVC) 34 #define WTF_ALIGN_OF(type) __alignof(type) 35 #define WTF_ALIGNED(variable_type, variable, n) __declspec(align(n)) variable_type variable 36 #else 37 #error WTF_ALIGN macros need alignment control. 38 #endif 39 40 #if COMPILER(GCC) 41 typedef char __attribute__((__may_alias__)) AlignedBufferChar; 42 #else 43 typedef char AlignedBufferChar; 44 #endif 45 46 template<size_t size, size_t alignment> struct AlignedBuffer; 47 template<size_t size> struct AlignedBuffer<size, 1> { AlignedBufferChar buffer[size]; }; 48 template<size_t size> struct AlignedBuffer<size, 2> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 2); }; 49 template<size_t size> struct AlignedBuffer<size, 4> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 4); }; 50 template<size_t size> struct AlignedBuffer<size, 8> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 8); }; 51 template<size_t size> struct AlignedBuffer<size, 16> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 16); }; 52 template<size_t size> struct AlignedBuffer<size, 32> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 32); }; 53 template<size_t size> struct AlignedBuffer<size, 64> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 64); }; 54 55 template <size_t size, size_t alignment> 56 void swap(AlignedBuffer<size, alignment>& a, AlignedBuffer<size, alignment>& b) 57 { 58 for (size_t i = 0; i < size; ++i) 59 std::swap(a.buffer[i], b.buffer[i]); 60 } 61 62 template <uintptr_t mask> 63 inline bool isAlignedTo(const void* pointer) 64 { 65 return !(reinterpret_cast<uintptr_t>(pointer) & mask); 66 } 67 } 68 69 #endif // WTF_Alignment_h 70