def generate_fitfile(data=None, endian='<'):
fit_data = (
generate_messages(
# local mesg 0, global mesg 0 (file_id)
mesg_num=0,
local_mesg_num=0,
endian=endian,
field_defs=[
# serial number, time_created, manufacturer
(3, 'uint32z'),
(4, 'uint32'),
(1, 'uint16'),
# product/garmin_product, number, type
(2, 'uint16'),
(5, 'uint16'),
(0, 'enum'),
],
# random serial number, random time, garmin, edge500, null, activity
data=[[558069241, 723842606, 1, 1036, (2**16) - 1, 4]],
))
if data:
fit_data += data
# Prototcol version 1.0, profile version 1.52
header = pack('<2BHI4s', 14, 16, 152, len(fit_data), b'.FIT')
file_data = header + pack('<' + Crc.FMT, Crc.calculate(header)) + fit_data
return file_data + pack('<' + Crc.FMT, Crc.calculate(file_data))
def _read_and_assert_crc(self, allow_zero=False):
# CRC Calculation is little endian from SDK
crc_computed, crc_read = self._crc.value, self._read_struct(Crc.FMT)
if not self.check_crc:
return
if crc_computed == crc_read or (allow_zero and crc_read == 0):
return
raise FitCRCError('CRC Mismatch [computed: %s, read: %s]' % (
Crc.format(crc_computed), Crc.format(crc_read)))
def _read_and_assert_crc(self, allow_zero=False):
# CRC Calculation is little endian from SDK
crc_computed, crc_read = self._crc.value, self._read_struct(Crc.FMT)
if not self.check_crc:
return
if crc_computed == crc_read or (allow_zero and crc_read == 0):
return
raise FitCRCError('CRC Mismatch [computed: %s, read: %s]' %
(Crc.format(crc_computed), Crc.format(crc_read)))
def _read_and_assert_crc(self, allow_zero=False):
# CRC Calculation is little endian from SDK
# TODO - How to handle the case of unterminated file? Error out and have user retry with check_crc=false?
crc_computed, crc_read = self._crc.value, self._read_struct(Crc.FMT)
if not self.check_crc:
return
if crc_computed == crc_read or (allow_zero and crc_read == 0):
return
raise FitCRCError('CRC Mismatch [computed: %s, read: %s]' % (
Crc.format(crc_computed), Crc.format(crc_read)))
def generate_fitfile(data=None, endian='<'):
fit_data = (
generate_messages(
# local mesg 0, global mesg 0 (file_id)
mesg_num=0, local_mesg_num=0, endian=endian, field_defs=[
# serial number, time_created, manufacturer
(3, 'uint32z'), (4, 'uint32'), (1, 'uint16'),
# product/garmin_product, number, type
(2, 'uint16'), (5, 'uint16'), (0, 'enum'),
],
# random serial number, random time, garmin, edge500, null, activity
data=[[558069241, 723842606, 1, 1036, (2 ** 16) - 1, 4]],
)
)
if data:
fit_data += data
# Prototcol version 1.0, profile version 1.52
header = pack('<2BHI4s', 14, 16, 152, len(fit_data), b'.FIT')
file_data = header + pack('<' + Crc.FMT, Crc.calculate(header)) + fit_data
return file_data + pack('<' + Crc.FMT, Crc.calculate(file_data))
def test_crc(self):
crc = Crc()
self.assertEqual(0, crc.value)
crc.update(b'\x0e\x10\x98\x00(\x00\x00\x00.FIT')
self.assertEqual(0xace7, crc.value)
# 0 must not change the crc
crc.update(0)
self.assertEqual(0xace7, crc.value)
def _parse_file_header(self):
# Initialize data
self._accumulators = {}
self._bytes_left = -1
self._complete = False
self._compressed_ts_accumulator = 0
self._crc = Crc()
self._local_mesgs = {}
# Every FIT must have 'FIT' string in the 8th byte. So, it seems your FIT is wrong.
header_data = self._read(12)
if header_data[8:12] != b'.FIT':
raise FitHeaderError("Invalid .FIT File Header")
# Larger fields are explicitly little endian from SDK
header_size, protocol_ver_enc, profile_ver_enc, data_size = self._read_struct(
'2BHI4x', data=header_data)
# Decode the same way the SDK does
self.protocol_version = float(
"%d.%d" % (protocol_ver_enc >> 4, protocol_ver_enc &
((1 << 4) - 1)))
self.profile_version = float(
"%d.%d" % (profile_ver_enc / 100, profile_ver_enc % 100))
# Consume extra header information
extra_header_size = header_size - 12
if extra_header_size > 0:
# Make sure extra field in header is at least 2 bytes to calculate CRC
if extra_header_size < 2:
raise FitHeaderError('Irregular File Header Size')
# Consume extra two bytes of header and check CRC
self._read_and_assert_crc(allow_zero=True)
# Consume any extra bytes, since header size "may be increased in
# "future to add additional optional information" (from SDK)
self._read(extra_header_size - 2)
# After we've consumed the header, set the bytes left to be read
self._bytes_left = data_size
def test_crc_format(self):
self.assertEqual('0x0000', Crc.format(0))
self.assertEqual('0x12AB', Crc.format(0x12AB))
