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bugfix for SSIDs from 10-15 #3

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bugfix for SSIDs from 10-15 #3

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39 changes: 21 additions & 18 deletions afsk/ax25.py
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Original file line number Diff line number Diff line change
Expand Up @@ -47,7 +47,7 @@ def digest(self):
# print "%r" % "".join([chr((~self.fcs & 0xff) % 256), chr((~self.fcs >> 8) % 256)])
# digest is two bytes, little endian
return struct.pack("<H", ~self.fcs % 2**16)

def fcs(bits):
'''
Append running bitwise FCS CRC checksum to end of generator
Expand Down Expand Up @@ -83,16 +83,16 @@ def fcs_validate(bits):
bit = buffer.pop(0)
fcs.update(bit)
yield bit

if buffer.tobytes() != fcs.digest():
raise Exception("FCS checksum invalid.")

class AX25(object):
def __init__(
self,
destination=b"APRS",
source=b"",
digipeaters=(b"RELAY", b"WIDE2-1"),
destination=b"APRS",
source=b"",
digipeaters=(b"RELAY", b"WIDE2-1"),
info=b"\""
):
self.flag = b"\x7e"
Expand All @@ -102,7 +102,7 @@ def __init__(
self.digipeaters = digipeaters

self.info = info

@classmethod
def callsign_encode(self, callsign):
callsign = callsign.upper()
Expand All @@ -111,6 +111,9 @@ def callsign_encode(self, callsign):
else:
ssid = b"0"

if 10 <= int(ssid) <= 15:
ssid = chr(ord(ssid[1])+10)

assert(len(ssid) == 1)
assert(len(callsign) <= 6)

Expand Down Expand Up @@ -153,7 +156,7 @@ def unparse(self):
bits.frombytes("".join([self.header(), self.info, self.fcs()]))

return flag + bit_stuff(bits) + flag

def __repr__(self):
return self.__str__()
def __str__(self):
Expand All @@ -174,7 +177,7 @@ def parse(cls, bits):
digipeaters=None,
info=None
)

def fcs(self):
content = bitarray(endian="little")
content.frombytes("".join([self.header(), self.info]))
Expand All @@ -189,31 +192,31 @@ def fcs(self):
class UI(AX25):
def __init__(
self,
destination=b"APRS",
source=b"",
destination=b"APRS",
source=b"",
digipeaters=(b"WIDE1-1", b"WIDE2-1"),
info=b""
):
AX25.__init__(
self,
destination,
source,
self,
destination,
source,
digipeaters,
info
)
self.control_field = b"\x03"
self.protocol_id = b"\xf0"

def main(arguments=None):
parser = argparse.ArgumentParser(description='')
parser.add_argument(
'-c',
'--callsign',
'--callsign',
required=True,
help='Your ham callsign. REQUIRED.'
)
parser.add_argument(
'info',
'info',
metavar='INFO',
help='APRS message body'
)
Expand All @@ -230,7 +233,7 @@ def main(arguments=None):
)
parser.add_argument(
'-o',
'--output',
'--output',
default=None,
help='Write audio to wav file. Use \'-\' for stdout.'
)
Expand All @@ -249,7 +252,7 @@ def main(arguments=None):

packet = UI(
destination=args.destination,
source=args.callsign,
source=args.callsign,
info=args.info,
digipeaters=args.digipeaters.split(b','),
)
Expand Down