| // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef MEDIA_MP4_OFFSET_BYTE_QUEUE_H_ |
| #define MEDIA_MP4_OFFSET_BYTE_QUEUE_H_ |
| |
| #include "base/basictypes.h" |
| #include "media/base/byte_queue.h" |
| #include "media/base/media_export.h" |
| |
| namespace media { |
| |
| // A wrapper around a ByteQueue which maintains a notion of a |
| // monotonically-increasing offset. All buffer access is done by passing these |
| // offsets into this class, going some way towards preventing the proliferation |
| // of many different meanings of "offset", "head", etc. |
| class MEDIA_EXPORT OffsetByteQueue { |
| public: |
| OffsetByteQueue(); |
| ~OffsetByteQueue(); |
| |
| // These work like their underlying ByteQueue counterparts. |
| void Reset(); |
| void Push(const uint8* buf, int size); |
| void Peek(const uint8** buf, int* size); |
| void Pop(int count); |
| |
| // Sets |buf| to point at the first buffered byte corresponding to |offset|, |
| // and |size| to the number of bytes available starting from that offset. |
| // |
| // It is an error if the offset is before the current head. It's not an error |
| // if the current offset is beyond tail(), but you will of course get back |
| // a null |buf| and a |size| of zero. |
| void PeekAt(int64 offset, const uint8** buf, int* size); |
| |
| // Marks the bytes up to (but not including) |max_offset| as ready for |
| // deletion. This is relatively inexpensive, but will not necessarily reduce |
| // the resident buffer size right away (or ever). |
| // |
| // Returns true if the full range of bytes were successfully trimmed, |
| // including the case where |max_offset| is less than the current head. |
| // Returns false if |max_offset| > tail() (although all bytes currently |
| // buffered are still cleared). |
| bool Trim(int64 max_offset); |
| |
| // The head and tail positions, in terms of the file's absolute offsets. |
| // tail() is an exclusive bound. |
| int64 head() { return head_; } |
| int64 tail() { return head_ + size_; } |
| |
| private: |
| // Synchronize |buf_| and |size_| with |queue_|. |
| void Sync(); |
| |
| ByteQueue queue_; |
| const uint8* buf_; |
| int size_; |
| int64 head_; |
| |
| DISALLOW_COPY_AND_ASSIGN(OffsetByteQueue); |
| }; |
| |
| } // namespace media |
| |
| #endif // MEDIA_MP4_MP4_STREAM_PARSER_H_ |