def extract_data(self, timestamp, data, offset):
"""Extract the data from the feature's raw data.
Args:
timestamp (int): Data's timestamp.
data (str): The data read from the feature.
offset (int): Offset where to start reading data.
Returns:
:class:`blue_st_sdk.feature.ExtractedData`: Container of the number
of bytes read and the extracted data.
Raises:
:exc:`blue_st_sdk.utils.blue_st_exceptions.InvalidDataException`
if the data array has not enough data to read.
"""
if len(data) - offset < self.DATA_LENGTH_BYTES:
raise InvalidDataException(
'There are no %d bytes available to read.' \
% (self.DATA_LENGTH_BYTES))
sample = Sample(
[LittleEndian.bytes_to_int32(data, offset) / self.SCALE_FACTOR],
self.get_fields_description(),
timestamp)
return ExtractedData(sample, self.DATA_LENGTH_BYTES)
def extract_data(self, timestamp, data, offset):
"""Extract the audio sync data from the feature's raw data.
In this case it reads a short integer (adpcm_index) and an integer
(adpcm_predsample).
Args:
data (bytearray): The data read from the feature (a 6 bytes array).
offset (int): Offset where to start reading data (0 by default).
Returns:
:class:`blue_st_sdk.feature.ExtractedData`: Container of the number
of bytes read (6) and the extracted data (audio sync info, a short
and an int).
Raises:
:exc:`blue_st_sdk.utils.blue_st_exceptions.InvalidDataException`
if the data array has not enough data to read.
"""
if len(data) != self.DATA_LENGTH_BYTES:
raise InvalidDataException(
'There are no %d bytes available to read.' \
% (self.DATA_LENGTH_BYTES))
sample = Sample([
LittleEndian.bytes_to_int16(data, 0),
LittleEndian.bytes_to_int32(data, 2)
], self.get_fields_description(), None)
return ExtractedData(sample, self.DATA_LENGTH_BYTES)
def update(self, data):
"""Update the value of the CRC.
Size of data in bytes must be multiple of 4.
Args:
data (bytearray): Data to compute the CRC value of.
Raises:
:exc:`ValueError` if the length of the data is not multiple of 4.
"""
if len(data) % 4 != 0:
raise ValueError('Size of data to compute the CRC on must be \
multiple of 4 [bytes].')
for i in range(0, len(data), 4):
tmp = LittleEndian.bytes_to_int32(data, i * 4)
self._current_crc = self._crc32_fast(self._current_crc, tmp)