The Android Open Source Project | dd7bc33 | 2009-03-03 19:32:55 -0800 | [diff] [blame] | 1 | /* |
Mathias Agopian | 9857d99 | 2013-04-01 15:17:55 -0700 | [diff] [blame] | 2 | * Copyright 2005 The Android Open Source Project |
The Android Open Source Project | dd7bc33 | 2009-03-03 19:32:55 -0800 | [diff] [blame] | 3 | * |
Mathias Agopian | 9857d99 | 2013-04-01 15:17:55 -0700 | [diff] [blame] | 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
The Android Open Source Project | dd7bc33 | 2009-03-03 19:32:55 -0800 | [diff] [blame] | 7 | * |
Mathias Agopian | 9857d99 | 2013-04-01 15:17:55 -0700 | [diff] [blame] | 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
The Android Open Source Project | dd7bc33 | 2009-03-03 19:32:55 -0800 | [diff] [blame] | 15 | */ |
| 16 | |
Mathias Agopian | 9857d99 | 2013-04-01 15:17:55 -0700 | [diff] [blame] | 17 | #ifndef ANDROID_PIXELFLINGER_SHARED_BUFFER_H |
| 18 | #define ANDROID_PIXELFLINGER_SHARED_BUFFER_H |
The Android Open Source Project | dd7bc33 | 2009-03-03 19:32:55 -0800 | [diff] [blame] | 19 | |
| 20 | #include <stdint.h> |
| 21 | #include <sys/types.h> |
| 22 | |
| 23 | // --------------------------------------------------------------------------- |
| 24 | |
| 25 | namespace android { |
Mathias Agopian | 9857d99 | 2013-04-01 15:17:55 -0700 | [diff] [blame] | 26 | namespace tinyutils { |
The Android Open Source Project | dd7bc33 | 2009-03-03 19:32:55 -0800 | [diff] [blame] | 27 | |
| 28 | class SharedBuffer |
| 29 | { |
| 30 | public: |
| 31 | |
| 32 | /* flags to use with release() */ |
| 33 | enum { |
| 34 | eKeepStorage = 0x00000001 |
| 35 | }; |
| 36 | |
| 37 | /*! allocate a buffer of size 'size' and acquire() it. |
| 38 | * call release() to free it. |
| 39 | */ |
| 40 | static SharedBuffer* alloc(size_t size); |
| 41 | |
| 42 | /*! free the memory associated with the SharedBuffer. |
| 43 | * Fails if there are any users associated with this SharedBuffer. |
| 44 | * In other words, the buffer must have been release by all its |
| 45 | * users. |
| 46 | */ |
| 47 | static ssize_t dealloc(const SharedBuffer* released); |
| 48 | |
| 49 | //! get the SharedBuffer from the data pointer |
| 50 | static inline const SharedBuffer* sharedBuffer(const void* data); |
| 51 | |
| 52 | //! access the data for read |
| 53 | inline const void* data() const; |
| 54 | |
| 55 | //! access the data for read/write |
| 56 | inline void* data(); |
| 57 | |
| 58 | //! get size of the buffer |
| 59 | inline size_t size() const; |
| 60 | |
| 61 | //! get back a SharedBuffer object from its data |
| 62 | static inline SharedBuffer* bufferFromData(void* data); |
| 63 | |
| 64 | //! get back a SharedBuffer object from its data |
| 65 | static inline const SharedBuffer* bufferFromData(const void* data); |
| 66 | |
| 67 | //! get the size of a SharedBuffer object from its data |
| 68 | static inline size_t sizeFromData(const void* data); |
| 69 | |
| 70 | //! edit the buffer (get a writtable, or non-const, version of it) |
| 71 | SharedBuffer* edit() const; |
| 72 | |
| 73 | //! edit the buffer, resizing if needed |
| 74 | SharedBuffer* editResize(size_t size) const; |
| 75 | |
| 76 | //! like edit() but fails if a copy is required |
| 77 | SharedBuffer* attemptEdit() const; |
| 78 | |
| 79 | //! resize and edit the buffer, loose it's content. |
| 80 | SharedBuffer* reset(size_t size) const; |
| 81 | |
| 82 | //! acquire/release a reference on this buffer |
| 83 | void acquire() const; |
| 84 | |
| 85 | /*! release a reference on this buffer, with the option of not |
| 86 | * freeing the memory associated with it if it was the last reference |
| 87 | * returns the previous reference count |
| 88 | */ |
| 89 | int32_t release(uint32_t flags = 0) const; |
| 90 | |
| 91 | //! returns wether or not we're the only owner |
| 92 | inline bool onlyOwner() const; |
| 93 | |
| 94 | |
| 95 | private: |
| 96 | inline SharedBuffer() { } |
| 97 | inline ~SharedBuffer() { } |
| 98 | inline SharedBuffer(const SharedBuffer&); |
| 99 | |
| 100 | // 16 bytes. must be sized to preserve correct alingment. |
| 101 | mutable int32_t mRefs; |
| 102 | size_t mSize; |
| 103 | uint32_t mReserved[2]; |
| 104 | }; |
| 105 | |
| 106 | // --------------------------------------------------------------------------- |
| 107 | |
| 108 | const SharedBuffer* SharedBuffer::sharedBuffer(const void* data) { |
| 109 | return data ? reinterpret_cast<const SharedBuffer *>(data)-1 : 0; |
| 110 | } |
| 111 | |
| 112 | const void* SharedBuffer::data() const { |
| 113 | return this + 1; |
| 114 | } |
| 115 | |
| 116 | void* SharedBuffer::data() { |
| 117 | return this + 1; |
| 118 | } |
| 119 | |
| 120 | size_t SharedBuffer::size() const { |
| 121 | return mSize; |
| 122 | } |
| 123 | |
| 124 | SharedBuffer* SharedBuffer::bufferFromData(void* data) |
| 125 | { |
| 126 | return ((SharedBuffer*)data)-1; |
| 127 | } |
| 128 | |
| 129 | const SharedBuffer* SharedBuffer::bufferFromData(const void* data) |
| 130 | { |
| 131 | return ((const SharedBuffer*)data)-1; |
| 132 | } |
| 133 | |
| 134 | size_t SharedBuffer::sizeFromData(const void* data) |
| 135 | { |
| 136 | return (((const SharedBuffer*)data)-1)->mSize; |
| 137 | } |
| 138 | |
| 139 | bool SharedBuffer::onlyOwner() const { |
| 140 | return (mRefs == 1); |
| 141 | } |
| 142 | |
Mathias Agopian | 9857d99 | 2013-04-01 15:17:55 -0700 | [diff] [blame] | 143 | } // namespace tinyutils |
| 144 | } // namespace android |
The Android Open Source Project | dd7bc33 | 2009-03-03 19:32:55 -0800 | [diff] [blame] | 145 | |
| 146 | // --------------------------------------------------------------------------- |
| 147 | |
Mathias Agopian | 9857d99 | 2013-04-01 15:17:55 -0700 | [diff] [blame] | 148 | #endif // ANDROID_PIXELFLINGER_SHARED_BUFFER_H |