Split the bit reader functionalities from the byte stream provider.

media/base/bit_reader_h264.h

+// Copyright (c) 2013 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_BASE_BIT_READER_H264_H_
+#define MEDIA_BASE_BIT_READER_H264_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "media/base/bit_reader_core.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+class MEDIA_EXPORT BitReaderH264
+    : private BitReaderCore::ByteStreamProvider  {

[damienv1, 2013/12/28 06:27:40]

Should be NON_EXPORTED_BASE(private BitReaderCore::ByteStreamProvider)

+ public:
+  // Initialize the reader to start reading at |data|, |size| being size
+  // of |data| in bytes.
+  BitReaderH264(const uint8* data, int size);
+  virtual ~BitReaderH264();
+
+  template<typename T> bool ReadBits(int num_bits, T* out) {
+    return bit_reader_core_.ReadBits(num_bits, out);
+  }
+
+  bool ReadFlag(bool* flag) {
+    return bit_reader_core_.ReadFlag(flag);
+  }
+
+  bool SkipBits(int num_bits) {
+    return bit_reader_core_.SkipBits(num_bits);
+  }
+
+  int GetBitCount() {
+    return bit_reader_core_.GetBitCount();
+  }
+
+  // Read an unsigned exp-golomb value.
+  // Return a negative number if the value cannot be read.
+  // Return the number of bits used by the exp-golomb code.
+  // Note: it is up to the caller to check for a possible overflow
+  // based on the returned exp-golomb code size.
+  int ReadUE(uint32* out);
+
+  // See the definition of more_rbsp_data() in spec.
+  bool HasMoreRBSPData();
+
+ private:
+  // BitReaderCore::ByteStreamProvider implementation.
+  virtual int GetBytes(int max_n, const uint8** out) OVERRIDE;
+  virtual int GetBytesLeft() const OVERRIDE;
+
+  // Pointer to the next unread byte in the stream.
+  const uint8* data_;
+
+  // Bytes left in the stream.
+  int bytes_left_;
+
+  // Array used to return some bytes when some start code emulation prevention
+  // bytes are detected.
+  uint8 data_window_[8];
+
+  // Last two bytes read from the stream.
+  uint32 prev_two_bytes_;
+
+  BitReaderCore bit_reader_core_;
+
+  DISALLOW_COPY_AND_ASSIGN(BitReaderH264);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_BIT_READER_H264_H_