def pretty(self):
str= "IME: "+self._pretty_header()+" "
for block in xrange(len(self.descrambled)):
b=self.descrambled[block]
if len(b)==31:
(errs,foo)=nrepair(self.poly,b)
res=ndivide(self.poly,b)
parity=(foo).count('1') % 2
str+="{%s %s/%04d E%s P%d}"%(b[:21],b[21:31],res,("0","1","2","-")[errs],parity)
elif len(b)==32:
(errs,foo)=nrepair(self.poly,b[:31])
res=ndivide(self.poly,b[:31])
parity=(foo+b[31]).count('1') % 2
str+="{%s %s %s/%04d E%s P%d}"%(b[:21],b[21:31],b[31],res,("0","1","2","-")[errs],parity)
else:
str+="length=%d?"%len(b)
str+=self._pretty_trailer()
return str
def pretty(self):
str = "IME: " + self._pretty_header() + " "
for block in xrange(len(self.descrambled)):
b = self.descrambled[block]
if len(b) == 31:
(errs, foo) = nrepair(self.poly, b)
res = ndivide(self.poly, b)
parity = (foo).count('1') % 2
str += "{%s %s/%04d E%s P%d}" % (b[:21], b[21:31], res,
("0", "1", "2",
"-")[errs], parity)
elif len(b) == 32:
(errs, foo) = nrepair(self.poly, b[:31])
res = ndivide(self.poly, b[:31])
parity = (foo + b[31]).count('1') % 2
str += "{%s %s %s/%04d E%s P%d}" % (
b[:21], b[21:31], b[31], res,
("0", "1", "2", "-")[errs], parity)
else:
str += "length=%d?" % len(b)
str += self._pretty_trailer()
return str
def __init__(self, imsg):
self.__dict__ = copy.deepcopy(imsg.__dict__)
if self.msgtype == "MS":
poly = messaging_bch_poly
elif self.msgtype == "RA":
poly = ringalert_bch_poly
elif self.msgtype == "BC":
poly = ringalert_bch_poly
elif self.msgtype == "DA":
poly = acch_bch_poly
else:
raise ParserError("unknown Iridium message type")
self.bitstream_messaging = ""
self.bitstream_bch = ""
self.oddbits = ""
self.fixederrs = 0
self.bch = []
for block in self.descrambled:
if len(block) != 32 and len(block) != 31:
raise ParserError("unknown BCH block len:%d" % len(block))
if len(block) == 32:
parity = block[31]
bits = block[:31]
result = ndivide(poly, bits)
errs = 0
if result != 0:
(errs, bits) = nrepair(poly, bits)
if errs > 0:
self.fixederrs += 1
if (errs < 0):
self._new_error("BCH decode failed")
if len(block) == 32:
parity = (bits + parity).count('1') % 2
elif len(block) == 31:
parity = (bits).count('1') % 2
# if parity==1: raise ParserError("Parity error")
self.bch.append((result, errs, parity))
self.bitstream_bch += block[:21]
self.bitstream_messaging += block[1:21]
self.oddbits += block[0]
if len(self.bitstream_bch) == 0:
self._new_error("No data to descramble")
def __init__(self,imsg):
self.__dict__=copy.deepcopy(imsg.__dict__)
if self.msgtype == "MS":
poly=messaging_bch_poly
elif self.msgtype == "RA":
poly=ringalert_bch_poly
elif self.msgtype == "BC":
poly=ringalert_bch_poly
elif self.msgtype == "DA":
poly=acch_bch_poly
else:
raise ParserError("unknown Iridium message type")
self.bitstream_messaging=""
self.bitstream_bch=""
self.oddbits=""
self.fixederrs=0
self.bch=[]
for block in self.descrambled:
if len(block)!=32 and len(block)!=31:
raise ParserError("unknown BCH block len:%d"%len(block))
if len(block)==32:
parity=block[31]
bits=block[:31]
result=ndivide(poly,bits)
errs=0
if result!=0:
(errs,bits)=nrepair(poly, bits)
if errs>0:
self.fixederrs+=1
if(errs<0):
self._new_error("BCH decode failed")
if len(block)==32:
parity=(bits+parity).count('1') % 2
elif len(block)==31:
parity=(bits).count('1') % 2
# if parity==1: raise ParserError("Parity error")
self.bch.append((result,errs,parity))
self.bitstream_bch+=block[:21]
self.bitstream_messaging+=block[1:21]
self.oddbits+=block[0]
if len(self.bitstream_bch)==0:
self._new_error("No data to descramble")
