def seterror(self, p):
"""Convenience method to set error annotation (or parameters) in `p`.
:return: Modified packet with updated parameters/annotations.
By default, if packet `p` has a `CRC32` layer, this method will set the
'crcerror' field, otherwise this method will set the 'crcerror'
annotation to 1.
**Overload this method as needed.**
"""
hascrc = CRC32.supported(p)
hasanno = ANNO.supported(p)
if hascrc:
p[CRC32].crcerror = 1
elif hasanno:
p.setanno('crcerror', 1)
else:
raise RuntimeError, "[PHY]: seterror() failed to find packet!"
def decode_data(self, p):
"""Waveform-level decoding of packet payload.
:param p: Packet to decode.
:return: Decoded data string.
"""
# check annotations
assert isinstance(p, Dot11N)
for a in ['cif-rxts', 'dot11n-header', 'dot11n-detect', 'dot11n-rxadded']:
errmsg = "[DOT11N]: Cannot find '%s' annotation!"%(a)
assert ANNO.supports(p, a), errmsg
errmsg = "[DOT11N]: Packet was not added to input!"
assert p.hasanno('dot11n-rxadded'), errmsg
errmsg = "[DOT11N]: Packet was not detected!"
assert p.getanno('dot11n-detect'), errmsg
header = p.getanno('dot11n-header')
errmsg = "[DOT11N]: Header decoding failed before decode_data()!"
assert (header=="success"), errmsg
# get parameters to check startidx
Ngi = int(DOT11N_TGI*DOT11N_BANDWIDTH)
prepad = int(self.MINPAD + DOT11N_TSHORT*DOT11N_BANDWIDTH)
startidx = self.receiver.start_index() - prepad
## startidx = -8 # overwrite startidx
## self.receiver.set_start_index(prepad+startidx)
# decode payload -> check if startidx is valid
y = self.getrxinput(p)
data = self.receiver.decode_data(y)
# check if decoding error occurred
# -> do contents of data match and does CRC pass?
crcchk, error = "FAIL", True
if (data == str(p.payload)):
if not CRC32.haserror(data):
crcchk = "OK"
error = False
# hamming distance between decoded data and packet p
hdist = hamming_distance(data, str(p.payload) )
self.log("CRC", p.payload, crcchk=crcchk, error=error, hdist=hdist)
# clean up waveform annotations
self.delrxwaveform(p)
# return decoding parameters
param = {'data':data, 'error':error, 'nerror':hdist}
# return decoded data
return param
def haserror(self, p, *args, **kwargs):
"""Convenience method to determine if packet `p` has an error.
:param args: Additional arguments passed to `CRC32.haserror()`.
:param kwargs: Keyword arguments passed to `CRC32.haserror()`.
:return: Boolean; true if error is found; false otherwise.
By default, this method calls `CRC32.haserror()`. If no `CRC32` layer is
found, or no 'crcerror' annotation is found the packet is assumed to be
error-free.
**Overload this method as needed to change this operation.**
:note: This method ignores the CRC when `checkcrc` is set to false.
"""
hascrc = isinstance(p, Packet) and p.haslayer(CRC32)
hasanno = ANNO.supported(p) and p.hasanno('crcerror')
crcerror = (hascrc or hasanno) and CRC32.haserror(p,*args,**kwargs)
if not self.checkcrc:
crcerror = False # assume no error when checkcrc is false
return crcerror
