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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // AlignedMemory is a POD type that gives you a portable way to specify static | 5 // AlignedMemory is a POD type that gives you a portable way to specify static |
6 // or local stack data of a given alignment and size. For example, if you need | 6 // or local stack data of a given alignment and size. For example, if you need |
7 // static storage for a class, but you want manual control over when the object | 7 // static storage for a class, but you want manual control over when the object |
8 // is constructed and destructed (you don't want static initialization and | 8 // is constructed and destructed (you don't want static initialization and |
9 // destruction), use AlignedMemory: | 9 // destruction), use AlignedMemory: |
10 // | 10 // |
11 // static AlignedMemory<sizeof(MyClass), ALIGNOF(MyClass)> my_class; | 11 // static AlignedMemory<sizeof(MyClass), ALIGNOF(MyClass)> my_class; |
12 // | 12 // |
13 // // ... at runtime: | 13 // // ... at runtime: |
14 // new(my_class.void_data()) MyClass(); | 14 // new(my_class.void_data()) MyClass(); |
15 // | 15 // |
16 // // ... use it: | 16 // // ... use it: |
17 // MyClass* mc = my_class.data_as<MyClass>(); | 17 // MyClass* mc = my_class.data_as<MyClass>(); |
18 // | 18 // |
19 // // ... later, to destruct my_class: | 19 // // ... later, to destruct my_class: |
20 // my_class.data_as<MyClass>()->MyClass::~MyClass(); | 20 // my_class.data_as<MyClass>()->MyClass::~MyClass(); |
21 // | |
22 // Alternatively, a runtime sized aligned allocation can be created: | |
23 // | |
24 // float* my_array = static_cast<float*>(AlignedAlloc(size, alignment)); | |
25 // | |
26 // // ... later, to release the memory: | |
27 // AlignedFree(my_array); | |
28 // | |
29 // Or using scoped_ptr_malloc: | |
30 // | |
31 // scoped_ptr_malloc<float, ScopedPtrAlignedFree> my_array( | |
32 // static_cast<float*>(AlignedAlloc(size, alignment))); | |
33 | 21 |
34 #ifndef BASE_MEMORY_ALIGNED_MEMORY_H_ | 22 #ifndef BASE_MEMORY_ALIGNED_MEMORY_H_ |
35 #define BASE_MEMORY_ALIGNED_MEMORY_H_ | 23 #define BASE_MEMORY_ALIGNED_MEMORY_H_ |
36 | 24 |
37 #include "base/base_export.h" | |
38 #include "base/basictypes.h" | 25 #include "base/basictypes.h" |
39 #include "base/compiler_specific.h" | 26 #include "base/compiler_specific.h" |
40 | 27 #include "base/logging.h" |
41 #if defined(COMPILER_MSVC) | |
42 #include <malloc.h> | |
43 #else | |
44 #include <stdlib.h> | |
45 #endif | |
46 | 28 |
47 namespace base { | 29 namespace base { |
48 | 30 |
49 // AlignedMemory is specialized for all supported alignments. | 31 // AlignedMemory is specialized for all supported alignments. |
50 // Make sure we get a compiler error if someone uses an unsupported alignment. | 32 // Make sure we get a compiler error if someone uses an unsupported alignment. |
51 template <size_t Size, size_t ByteAlignment> | 33 template <size_t Size, size_t ByteAlignment> |
52 struct AlignedMemory {}; | 34 struct AlignedMemory {}; |
53 | 35 |
54 #define BASE_DECL_ALIGNED_MEMORY(byte_alignment) \ | 36 #define BASE_DECL_ALIGNED_MEMORY(byte_alignment) \ |
55 template <size_t Size> \ | 37 template <size_t Size> \ |
56 class AlignedMemory<Size, byte_alignment> { \ | 38 class AlignedMemory<Size, byte_alignment> { \ |
57 public: \ | 39 public: \ |
58 void* void_data() { return static_cast<void*>(data_); } \ | 40 ALIGNAS(byte_alignment) uint8 data_[Size]; \ |
| 41 void* void_data() { return reinterpret_cast<void*>(data_); } \ |
59 const void* void_data() const { \ | 42 const void* void_data() const { \ |
60 return static_cast<const void*>(data_); \ | 43 return reinterpret_cast<const void*>(data_); \ |
61 } \ | 44 } \ |
62 template<typename Type> \ | 45 template<typename Type> \ |
63 Type* data_as() { return static_cast<Type*>(void_data()); } \ | 46 Type* data_as() { return reinterpret_cast<Type*>(void_data()); } \ |
64 template<typename Type> \ | 47 template<typename Type> \ |
65 const Type* data_as() const { \ | 48 const Type* data_as() const { \ |
66 return static_cast<const Type*>(void_data()); \ | 49 return reinterpret_cast<const Type*>(void_data()); \ |
67 } \ | 50 } \ |
68 private: \ | 51 private: \ |
69 ALIGNAS(byte_alignment) uint8 data_[Size]; \ | |
70 void* operator new(size_t); \ | 52 void* operator new(size_t); \ |
71 void operator delete(void*); \ | 53 void operator delete(void*); \ |
72 } | 54 } |
73 | 55 |
74 // Specialization for all alignments is required because MSVC (as of VS 2008) | 56 // Specialization for all alignments is required because MSVC (as of VS 2008) |
75 // does not understand ALIGNAS(ALIGNOF(Type)) or ALIGNAS(template_param). | 57 // does not understand ALIGNAS(ALIGNOF(Type)) or ALIGNAS(template_param). |
76 // Greater than 4096 alignment is not supported by some compilers, so 4096 is | 58 // Greater than 4096 alignment is not supported by some compilers, so 4096 is |
77 // the maximum specified here. | 59 // the maximum specified here. |
78 BASE_DECL_ALIGNED_MEMORY(1); | 60 BASE_DECL_ALIGNED_MEMORY(1); |
79 BASE_DECL_ALIGNED_MEMORY(2); | 61 BASE_DECL_ALIGNED_MEMORY(2); |
80 BASE_DECL_ALIGNED_MEMORY(4); | 62 BASE_DECL_ALIGNED_MEMORY(4); |
81 BASE_DECL_ALIGNED_MEMORY(8); | 63 BASE_DECL_ALIGNED_MEMORY(8); |
82 BASE_DECL_ALIGNED_MEMORY(16); | 64 BASE_DECL_ALIGNED_MEMORY(16); |
83 BASE_DECL_ALIGNED_MEMORY(32); | 65 BASE_DECL_ALIGNED_MEMORY(32); |
84 BASE_DECL_ALIGNED_MEMORY(64); | 66 BASE_DECL_ALIGNED_MEMORY(64); |
85 BASE_DECL_ALIGNED_MEMORY(128); | 67 BASE_DECL_ALIGNED_MEMORY(128); |
86 BASE_DECL_ALIGNED_MEMORY(256); | 68 BASE_DECL_ALIGNED_MEMORY(256); |
87 BASE_DECL_ALIGNED_MEMORY(512); | 69 BASE_DECL_ALIGNED_MEMORY(512); |
88 BASE_DECL_ALIGNED_MEMORY(1024); | 70 BASE_DECL_ALIGNED_MEMORY(1024); |
89 BASE_DECL_ALIGNED_MEMORY(2048); | 71 BASE_DECL_ALIGNED_MEMORY(2048); |
90 BASE_DECL_ALIGNED_MEMORY(4096); | 72 BASE_DECL_ALIGNED_MEMORY(4096); |
91 | 73 |
92 #undef BASE_DECL_ALIGNED_MEMORY | 74 } // base |
93 | |
94 BASE_EXPORT void* AlignedAlloc(size_t size, size_t alignment); | |
95 | |
96 inline void AlignedFree(void* ptr) { | |
97 #if defined(COMPILER_MSVC) | |
98 _aligned_free(ptr); | |
99 #else | |
100 free(ptr); | |
101 #endif | |
102 } | |
103 | |
104 // Helper class for use with scoped_ptr_malloc. | |
105 class BASE_EXPORT ScopedPtrAlignedFree { | |
106 public: | |
107 inline void operator()(void* ptr) const { | |
108 AlignedFree(ptr); | |
109 } | |
110 }; | |
111 | |
112 } // namespace base | |
113 | 75 |
114 #endif // BASE_MEMORY_ALIGNED_MEMORY_H_ | 76 #endif // BASE_MEMORY_ALIGNED_MEMORY_H_ |
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