vp9_raw_bits_reader.cc 1.4 KB

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  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. #include "media/filters/vp9_raw_bits_reader.h"
  5. #include <limits.h>
  6. #include <memory>
  7. #include "base/check_op.h"
  8. #include "media/base/bit_reader.h"
  9. namespace media {
  10. Vp9RawBitsReader::Vp9RawBitsReader() : valid_(true) {}
  11. Vp9RawBitsReader::~Vp9RawBitsReader() = default;
  12. void Vp9RawBitsReader::Initialize(const uint8_t* data, size_t size) {
  13. DCHECK(data);
  14. reader_ = std::make_unique<BitReader>(data, size);
  15. valid_ = true;
  16. }
  17. bool Vp9RawBitsReader::ReadBool() {
  18. DCHECK(reader_);
  19. if (!valid_)
  20. return false;
  21. int value = 0;
  22. valid_ = reader_->ReadBits(1, &value);
  23. return valid_ ? value == 1 : false;
  24. }
  25. int Vp9RawBitsReader::ReadLiteral(int bits) {
  26. DCHECK(reader_);
  27. if (!valid_)
  28. return 0;
  29. int value = 0;
  30. DCHECK_LT(static_cast<size_t>(bits), sizeof(value) * 8);
  31. valid_ = reader_->ReadBits(bits, &value);
  32. return valid_ ? value : 0;
  33. }
  34. int Vp9RawBitsReader::ReadSignedLiteral(int bits) {
  35. int value = ReadLiteral(bits);
  36. return ReadBool() ? -value : value;
  37. }
  38. size_t Vp9RawBitsReader::GetBytesRead() const {
  39. DCHECK(reader_);
  40. return (reader_->bits_read() + 7) / 8;
  41. }
  42. bool Vp9RawBitsReader::ConsumeTrailingBits() {
  43. DCHECK(reader_);
  44. int bits_left = GetBytesRead() * 8 - reader_->bits_read();
  45. return ReadLiteral(bits_left) == 0;
  46. }
  47. } // namespace media