1// Copyright 2015 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// Note: ported from Chromium commit head: 2de6929
5
6#include "vp9_raw_bits_reader.h"
7
8#include <limits.h>
9
10#include "base/logging.h"
11#include "bit_reader.h"
12
13namespace media {
14
15Vp9RawBitsReader::Vp9RawBitsReader() : valid_(true) {}
16
17Vp9RawBitsReader::~Vp9RawBitsReader() = default;
18
19void Vp9RawBitsReader::Initialize(const uint8_t* data, size_t size) {
20  DCHECK(data);
21  reader_.reset(new BitReader(data, size));
22  valid_ = true;
23}
24
25bool Vp9RawBitsReader::ReadBool() {
26  DCHECK(reader_);
27  if (!valid_)
28    return false;
29
30  int value = 0;
31  valid_ = reader_->ReadBits(1, &value);
32  return valid_ ? value == 1 : false;
33}
34
35int Vp9RawBitsReader::ReadLiteral(int bits) {
36  DCHECK(reader_);
37  if (!valid_)
38    return 0;
39
40  int value = 0;
41  DCHECK_LT(static_cast<size_t>(bits), sizeof(value) * 8);
42  valid_ = reader_->ReadBits(bits, &value);
43  return valid_ ? value : 0;
44}
45
46int Vp9RawBitsReader::ReadSignedLiteral(int bits) {
47  int value = ReadLiteral(bits);
48  return ReadBool() ? -value : value;
49}
50
51size_t Vp9RawBitsReader::GetBytesRead() const {
52  DCHECK(reader_);
53  return (reader_->bits_read() + 7) / 8;
54}
55
56bool Vp9RawBitsReader::ConsumeTrailingBits() {
57  DCHECK(reader_);
58  int bits_left = GetBytesRead() * 8 - reader_->bits_read();
59  return ReadLiteral(bits_left) == 0;
60}
61
62}  // namespace media
63