def decode(self, input_file):
# Encode aivdm data back into binary
fragments = []
payload = self._aivdm[1][0]
data = Data(input_file)
while data:
try:
calculated_crc = self._get_crc(data)
packet = decode(self._aivdm[0], data)
if packet.checksum != calculated_crc:
sys.stderr.write('Crc mismatch; expected %02X, but '
'calculated %02X. Skipping packet.\n' %
(packet.checksum, calculated_crc))
continue
bits = encode(payload, list(ord(c.character) for c in packet.payload))
bits = bits.pop(len(bits) - packet.num_fill_bits)
if len(fragments) == packet.fragment_number - 1:
fragments.append(bits)
if len(fragments) == packet.fragment_count:
self._decode_ais(reduce(operator.add, fragments))
fragments = []
else:
sys.stderr.write('Expected fragment number %i, got %i (of %i)\n' % (
len(fragments) + 1, packet.fragment_number, packet.fragment_count))
fragments = []
except DecodeError, ex:
filename, line_number, column_number = self._aivdm[2][ex.entry]
sys.stderr.write('%s[%i] - %s\n' % (filename, line_number, ex))
fragments = []
# Read to the next newline
while data and data.pop(8).text('ascii') != '\n':
pass
