media/base/byte_queue.h

   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
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_BASE_BYTE_QUEUE_H_
   6 #define MEDIA_BASE_BYTE_QUEUE_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "media/base/media_export.h"
  11
  12 namespace media {
  13
  14 // Represents a queue of bytes.
  15 // Data is added to the end of the queue via an Push() call and removed via
  16 // Pop(). The contents of the queue can be observed via the Peek() method.
  17 // This class manages the underlying storage of the queue and tries to minimize
  18 // the number of buffer copies when data is appended and removed.
  19 class MEDIA_EXPORT ByteQueue {
  20  public:
  21   ByteQueue();
  22   ~ByteQueue();
  23
  24   // Reset the queue to the empty state.
  25   void Reset();
  26
  27   // Appends new bytes onto the end of the queue.
  28   void Push(const uint8* data, int size);
  29
  30   // Get a pointer to the front of the queue and the queue size.
  31   // These values are only valid until the next Push() or
  32   // Pop() call.
  33   void Peek(const uint8** data, int* size) const;
  34
  35   // Remove |count| bytes from the front of the queue.
  36   void Pop(int count);
  37
  38  private:
  39   // Returns a pointer to the front of the queue.
  40   uint8* front() const;
  41
  42   scoped_ptr<uint8[]> buffer_;
  43
  44   // Size of |buffer_|.
  45   size_t size_;
  46
  47   // Offset from the start of |buffer_| that marks the front of the queue.
  48   size_t offset_;
  49
  50   // Number of bytes stored in the queue.
  51   int used_;
  52
  53   DISALLOW_COPY_AND_ASSIGN(ByteQueue);
  54 };
  55
  56 }  // namespace media
  57
  58 #endif  // MEDIA_BASE_BYTE_QUEUE_H_