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| 1 // Copyright (c) 2013 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2013 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 #ifndef CONTENT_COMMON_PARTIAL_CIRCULAR_BUFFER_H_ | 5 #ifndef CHROME_COMMON_PARTIAL_CIRCULAR_BUFFER_H_ |
| 6 #define CONTENT_COMMON_PARTIAL_CIRCULAR_BUFFER_H_ | 6 #define CHROME_COMMON_PARTIAL_CIRCULAR_BUFFER_H_ |
| 7 | 7 |
| 8 #include "base/basictypes.h" | 8 #include "base/basictypes.h" |
| 9 #include "base/gtest_prod_util.h" | 9 #include "base/gtest_prod_util.h" |
| 10 #include "content/common/content_export.h" | |
| 11 | 10 |
| 12 namespace content { | 11 namespace chrome { |
| 13 | 12 |
| 14 // A wrapper around a memory buffer that allows circular read and write with a | 13 // A wrapper around a memory buffer that allows circular read and write with a |
| 15 // selectable wrapping position. Buffer layout (after wrap; H is header): | 14 // selectable wrapping position. Buffer layout (after wrap; H is header): |
| 16 // ----------------------------------------------------------- | 15 // ----------------------------------------------------------- |
| 17 // | H | Beginning | End | Middle | | 16 // | H | Beginning | End | Middle | |
| 18 // ----------------------------------------------------------- | 17 // ----------------------------------------------------------- |
| 19 // ^---- Non-wrapping -----^ ^--------- Wrapping ----------^ | 18 // ^---- Non-wrapping -----^ ^--------- Wrapping ----------^ |
| 20 // The non-wrapping part is never overwritten. The wrapping part will be | 19 // The non-wrapping part is never overwritten. The wrapping part will be |
| 21 // circular. The very first part is the header (see the BufferData struct | 20 // circular. The very first part is the header (see the BufferData struct |
| 22 // below). It consists of the following information: | 21 // below). It consists of the following information: |
| 23 // - Length written to the buffer (not including header). | 22 // - Length written to the buffer (not including header). |
| 24 // - Wrapping position. | 23 // - Wrapping position. |
| 25 // - End position of buffer. (If the last byte is at x, this will be x + 1.) | 24 // - End position of buffer. (If the last byte is at x, this will be x + 1.) |
| 26 // Users of wrappers around the same underlying buffer must ensure that writing | 25 // Users of wrappers around the same underlying buffer must ensure that writing |
| 27 // is finished before reading is started. | 26 // is finished before reading is started. |
| 28 class CONTENT_EXPORT PartialCircularBuffer { | 27 class PartialCircularBuffer { |
| 29 public: | 28 public: |
| 30 // Use for reading. |buffer_size| is in bytes and must be larger than the | 29 // Use for reading. |buffer_size| is in bytes and must be larger than the |
| 31 // header size (see above). | 30 // header size (see above). |
| 32 PartialCircularBuffer(void* buffer, uint32 buffer_size); | 31 PartialCircularBuffer(void* buffer, uint32 buffer_size); |
| 33 | 32 |
| 34 // Use for writing. |buffer_size| is in bytes and must be larger than the | 33 // Use for writing. |buffer_size| is in bytes and must be larger than the |
| 35 // header size (see above). | 34 // header size (see above). |
| 36 PartialCircularBuffer(void* buffer, | 35 PartialCircularBuffer(void* buffer, |
| 37 uint32 buffer_size, | 36 uint32 buffer_size, |
| 38 uint32 wrap_position); | 37 uint32 wrap_position); |
| (...skipping 19 matching lines...) Expand all Loading... |
| 58 // Used for reading and writing. | 57 // Used for reading and writing. |
| 59 BufferData* buffer_data_; | 58 BufferData* buffer_data_; |
| 60 uint32 memory_buffer_size_; | 59 uint32 memory_buffer_size_; |
| 61 uint32 data_size_; | 60 uint32 data_size_; |
| 62 uint32 position_; | 61 uint32 position_; |
| 63 | 62 |
| 64 // Used for reading. | 63 // Used for reading. |
| 65 uint32 total_read_; | 64 uint32 total_read_; |
| 66 }; | 65 }; |
| 67 | 66 |
| 68 } // namespace content | 67 } // namespace chrome |
| 69 | 68 |
| 70 #endif // CONTENT_COMMON_PARTIAL_CIRCULAR_BUFFER_H_ | 69 #endif // CHROME_COMMON_PARTIAL_CIRCULAR_BUFFER_H_ |
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