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Additional work toward new parser. Added fields for extended squitter.

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This commit is contained in:
Nick Foster 2012-06-22 17:28:55 -07:00
parent ba153e52ed
commit a45531b15c
1 changed files with 110 additions and 36 deletions
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146
python/modes_parse.py
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@ -27,11 +27,102 @@ import math
from modes_exceptions import *
#this implements a packet class which can retrieve its own fields.
class modes_data:
class data_field:
def __init__(self, data):
self.data = data
#this depends on packet type so we initialize it here
#there's probably a cleaner way to do it.
fields = { }
types = { }
subfields = { } #fields to return objects instead of just returning bits
startbit = 0 #field offset applied to all fields. used for offsetting subtypes to reconcile with spec.
#get a particular field from the data
def __getitem__(self, fieldname):
if fieldname in self.types[self.get_type()]: #verify it exists in this packet type
if fieldname in self.subfields:
#create a new subfield object and return it
return self.subfields[fieldname](self.get_bits(self.fields[fieldname]))
return self.get_bits(self.fields[fieldname])
else:
raise FieldNotInPacket(fieldname)
#grab all the fields in the packet as a dict
def get_fields(self):
return {field: self[field] for field in self.types[self.get_type()]}
def get_type(self):
raise NotImplementedError
def get_numbits(self):
raise NotImplementedError
#retrieve bits from data given the offset and number of bits.
#the offset is both left-justified (LSB) and starts at 1, to
#correspond to the Mode S spec. Blame them.
def get_bits(self, arg):
(offset, num) = arg
return (self.data \
>> (self.get_numbits() - offset - num + self.startbit + 1)) \
& ((1 << num) - 1)
#type MB (extended squitter types 20,21) subfields
class mb_reply(data_field):
fields = { "acs": (45,20), "ais": (41,48), "ara": (41,14), "bcs": (65,16),
"bds": (33,8), "bds1": (33,4), "bds2": (37,4), "cfs": (41,4),
"ecs": (81,8), "mte": (60,1), "rac": (55,4), "rat": (59,1),
"tid": (33,26), "tida": (63,13), "tidb": (83,6), "tidr": (76,7),
"tti": (61,2)
}
startbit = 32 #fields offset by 32 to match documentation
#types are based on bds1 subfield
types = { 0: ["bds", "bds1", "bds2"], #TODO
1: ["bds", "bds1", "bds2", "cfs", "acs", "bcs"],
2: ["bds", "bds1", "bds2", "ais"],
3: ["bds", "bds1", "bds2", "ara", "rac", "rat",
"mte", "tti", "tida", "tidr", "tidb"]
}
def get_type(self):
bds1 = self.get_bits(self.fields["bds1"])
bds2 = self.get_bits(self.fields["bds2"])
if bds1 not in (0,1,2,3) or bds2 not in (0,):
raise NoHandlerError
return bds1
def get_numbits(self):
return 56
#type 17 extended squitter data
class me_reply(data_field):
#TODO: add comments explaining these fields
fields = { "ftc": (1,5), "ss": (6,2), "saf": (8,1), "alt": (9, 12),
"time": (21,1), "cpr": (22,1), "lat": (23, 17), "lon": (40, 17),
"mvt": (6,7), "gts": (13,1), "gtk": (14,7), "trs": (1,2),
"ats": (3,1), "cat": (6,3), "ident": (9,48), "sub": (6,3),
"dew": (10,1), "vew": (11,11), "dns": (22,1), "vns": (23,11),
"str": (34,1), "tr": (35,6), "svr": (41,1), "vr": (42,9),
"icf": (9,1), "ifr": (10,1), "nuc": (11,3), "gdew": (14,1),
"gvew": (15,10), "gdns": (25,1), "gvns": (26,10), "vrs": (36,1),
"gsvr": (37,1), "gvr": (38,9), "ghds": (49,1), "ghd": (50,6),
"mhs": (14,1), "hdg": (15,10), "ast": (25,1), "spd": (26,10),
"eps": (9,3)
#TODO: TCP, TCP+1/BDS 6,2
}
startbit = 0
types = { }
def get_type(self):
pass
def get_numbits(self):
return 56
class modes_reply(data_field):
def __init__(self, data):
data_field.__init__(self, data)
#TODO FIX PARITY FIELDS
self.parity_fields = {
"ap": (33+(self.get_numbits()-56),24),
"pi": (33+(self.get_numbits()-56),24)
@ -50,48 +141,31 @@ class modes_data:
types = { 0: ["df", "vs", "cc", "sl", "ri", "ac", "ap"],
4: ["df", "fs", "dr", "um", "ac", "ap"],
5: ["df", "fs", "dr", "um", "id", "ap"],
11: ["df", "ca", "aa", "pi"],
16: ["df", "vs", "sl", "ri", "ac", "mv", "ap"],
17: ["df", "ca", "aa", "me", "pi"],
20: ["df", "fs", "dr", "um", "ac", "mb", "ap"],
21: ["df", "fs", "dr", "um", "id", "mb", "ap"],
24: ["df", "ke", "nd", "md", "ap"]
11: ["df", "ca", "aa", "pi"],
16: ["df", "vs", "sl", "ri", "ac", "mv", "ap"],
17: ["df", "ca", "aa", "me", "pi"],
20: ["df", "fs", "dr", "um", "ac", "mb", "ap"],
21: ["df", "fs", "dr", "um", "id", "mb", "ap"],
24: ["df", "ke", "nd", "md", "ap"]
}
#packets which are 112 bits long
long_types = [16, 17, 20, 21, 24]
subfields = { "mb": mb_reply, "me": me_reply } #TODO MV, ME
#get a particular field from the data
def __getitem__(self, fieldname):
if fieldname in modes_data.types[self.get_bits(modes_data.fields["df"])]: #verify it exists in this packet type
if fieldname in self.parity_fields:
return self.get_bits(self.parity_fields[fieldname])
else:
return self.get_bits(modes_data.fields[fieldname])
else:
raise FieldNotInPacket(fieldname)
#grab all the fields in the packet as a dict
def get_fields(self):
return {field: self[field] for field in modes_data.types[self["df"]]}
#tell me if i'm an extended squitter or a normal Mode S reply
def is_long(self):
#can't use packet type because we use is_long() to get items, and
#this causes endless recursion
#return self["df"] in modes_data.long_types
return self.data > (1 << 56)
#how many bits are in the packet?
def get_numbits(self):
return 112 if self.is_long() else 56
#retrieve bits from data given the offset and number of bits.
#the offset is both left-justified (LSB) and starts at 1, to
#correspond to the Mode S spec. Blame them.
def get_bits(self, arg):
(offset, num) = arg
return (self.data >> (self.get_numbits() - offset - num + 1)) & ((1 << num) - 1)
def get_type(self):
return self.get_bits(self.fields["df"])
#TODO overload getitem to handle special parity fields
# #type MV (extended squitter type 16) subfields
# mv_fields = { "ara": (41,14), "mte": (60,1), "rac": (55,4), "rat": (59,1),
# "vds": (33,8), "vds1": (33,4), "vds2": (37,4)
# }
class modes_parse:
def __init__(self, mypos):