73 lines
2.4 KiB
C++
73 lines
2.4 KiB
C++
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef PACKAGER_MEDIA_BASE_OFFSET_BYTE_QUEUE_H_
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#define PACKAGER_MEDIA_BASE_OFFSET_BYTE_QUEUE_H_
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#include <cstdint>
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#include <packager/media/base/byte_queue.h>
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namespace shaka {
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namespace media {
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/// Wrapper around ByteQueue, which encapsulates the notion of a
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/// monotonically-increasing byte offset. All buffer access is done by passing
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/// these offsets into this class, reducing the proliferation of many different
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/// meanings of "offset", "head", etc.
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class OffsetByteQueue {
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public:
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OffsetByteQueue();
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~OffsetByteQueue();
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/// @name These work like their underlying ByteQueue counterparts.
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/// @{
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void Reset();
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void Push(const uint8_t* buf, int size);
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void Peek(const uint8_t** buf, int* size);
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void Pop(int count);
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/// @}
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/// Set @a buf to point at the first buffered byte corresponding to @a offset,
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/// and @a size to the number of bytes available starting from that offset.
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///
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/// It is an error if the offset is before the current head. It's not an error
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/// if the current offset is beyond tail(), but you will of course get back
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/// a null @a buf and a @a size of zero.
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void PeekAt(int64_t offset, const uint8_t** buf, int* size);
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/// Mark the bytes up to (but not including) @a max_offset as ready for
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/// deletion. This is relatively inexpensive, but will not necessarily reduce
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/// the resident buffer size right away (or ever).
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///
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/// @return true if the full range of bytes were successfully trimmed,
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/// including the case where @a max_offset is less than the current
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/// head.
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/// @return false if @a max_offset > tail() (although all bytes currently
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/// buffered are still cleared).
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bool Trim(int64_t max_offset);
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/// @return The head position, in terms of the file's absolute offset.
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int64_t head() { return head_; }
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/// @return The tail position (exclusive), in terms of the file's absolute
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/// offset.
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int64_t tail() { return head_ + size_; }
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private:
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// Synchronize |buf_| and |size_| with |queue_|.
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void Sync();
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ByteQueue queue_;
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const uint8_t* buf_;
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int size_;
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int64_t head_;
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DISALLOW_COPY_AND_ASSIGN(OffsetByteQueue);
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};
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} // namespace media
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} // namespace shaka
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#endif // PACKAGER_MEDIA_BASE_OFFSET_BYTE_QUEUE_H_
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