media/base/bit_reader.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_BIT_READER_H_
   6 #define MEDIA_BASE_BIT_READER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/compiler_specific.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "media/base/bit_reader_core.h"
  12 #include "media/base/media_export.h"
  13
  14 namespace media {
  15
  16 class MEDIA_EXPORT BitReader
  17     : NON_EXPORTED_BASE(private BitReaderCore::ByteStreamProvider)  {
  18  public:
  19   // Initialize the reader to start reading at |data|, |size| being size
  20   // of |data| in bytes.
  21   BitReader(const uint8* data, int size);
  22   virtual ~BitReader();
  23
  24   template<typename T> bool ReadBits(int num_bits, T* out) {
  25     return bit_reader_core_.ReadBits(num_bits, out);
  26   }
  27
  28   bool ReadFlag(bool* flag) {
  29     return bit_reader_core_.ReadFlag(flag);
  30   }
  31
  32   bool SkipBits(int num_bits) {
  33     return bit_reader_core_.SkipBits(num_bits);
  34   }
  35
  36   int bits_available() const {
  37     return initial_size_ * 8 - bits_read();
  38   }
  39
  40   int bits_read() const {
  41     return bit_reader_core_.bits_read();
  42   }
  43
  44  private:
  45   // BitReaderCore::ByteStreamProvider implementation.
  46   virtual int GetBytes(int max_n, const uint8** out) OVERRIDE;
  47
  48   // Total number of bytes that was initially passed to BitReader.
  49   const int initial_size_;
  50
  51   // Pointer to the next unread byte in the stream.
  52   const uint8* data_;
  53
  54   // Bytes left in the stream.
  55   int bytes_left_;
  56
  57   BitReaderCore bit_reader_core_;
  58
  59   DISALLOW_COPY_AND_ASSIGN(BitReader);
  60 };
  61
  62 }  // namespace media
  63
  64 #endif  // MEDIA_BASE_BIT_READER_H_