diff options
Diffstat (limited to 'chromium/media/base/bit_reader.cc')
-rw-r--r-- | chromium/media/base/bit_reader.cc | 83 |
1 files changed, 17 insertions, 66 deletions
diff --git a/chromium/media/base/bit_reader.cc b/chromium/media/base/bit_reader.cc index e4d83af7410..c0d30d66fdd 100644 --- a/chromium/media/base/bit_reader.cc +++ b/chromium/media/base/bit_reader.cc @@ -4,80 +4,31 @@ #include "media/base/bit_reader.h" -#include <algorithm> - namespace media { -BitReader::BitReader(const uint8* data, off_t size) - : data_(data), bytes_left_(size), num_remaining_bits_in_curr_byte_(0) { - DCHECK(data_ != NULL && bytes_left_ > 0); - - UpdateCurrByte(); +BitReader::BitReader(const uint8* data, int size) + : initial_size_(size), + data_(data), + bytes_left_(size), + bit_reader_core_(this) { + DCHECK(data != NULL); + DCHECK_GE(size, 0); } BitReader::~BitReader() {} -bool BitReader::SkipBits(int num_bits) { - DCHECK_GE(num_bits, 0); - DVLOG_IF(0, num_bits > 100) - << "BitReader::SkipBits inefficient for large skips"; - - // Skip any bits in the current byte waiting to be processed, then - // process full bytes until less than 8 bits remaining. - while (num_bits > 0 && num_bits > num_remaining_bits_in_curr_byte_) { - num_bits -= num_remaining_bits_in_curr_byte_; - num_remaining_bits_in_curr_byte_ = 0; - UpdateCurrByte(); - - // If there is no more data remaining, only return true if we - // skipped all that were requested. - if (num_remaining_bits_in_curr_byte_ == 0) - return (num_bits == 0); - } - - // Less than 8 bits remaining to skip. Use ReadBitsInternal to verify - // that the remaining bits we need exist, and adjust them as necessary - // for subsequent operations. - uint64 not_needed; - return ReadBitsInternal(num_bits, ¬_needed); -} - -int BitReader::bits_available() const { - return 8 * bytes_left_ + num_remaining_bits_in_curr_byte_; -} - -bool BitReader::ReadBitsInternal(int num_bits, uint64* out) { - DCHECK_LE(num_bits, 64); - - *out = 0; - - while (num_remaining_bits_in_curr_byte_ != 0 && num_bits != 0) { - int bits_to_take = std::min(num_remaining_bits_in_curr_byte_, num_bits); - - *out <<= bits_to_take; - *out += curr_byte_ >> (num_remaining_bits_in_curr_byte_ - bits_to_take); - num_bits -= bits_to_take; - num_remaining_bits_in_curr_byte_ -= bits_to_take; - curr_byte_ &= (1 << num_remaining_bits_in_curr_byte_) - 1; - - if (num_remaining_bits_in_curr_byte_ == 0) - UpdateCurrByte(); - } - - return num_bits == 0; -} - -void BitReader::UpdateCurrByte() { - DCHECK_EQ(num_remaining_bits_in_curr_byte_, 0); +int BitReader::GetBytes(int max_nbytes, const uint8** out) { + DCHECK_GE(max_nbytes, 0); + DCHECK(out); - if (bytes_left_ == 0) - return; + int nbytes = max_nbytes; + if (nbytes > bytes_left_) + nbytes = bytes_left_; - // Load a new byte and advance pointers. - curr_byte_ = *data_; - ++data_; - --bytes_left_; - num_remaining_bits_in_curr_byte_ = 8; + *out = data_; + data_ += nbytes; + bytes_left_ -= nbytes; + return nbytes; } } // namespace media |