openpilot is an open source driver assistance system. openpilot performs the functions of Automated Lane Centering and Adaptive Cruise Control for over 200 supported car makes and models.
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import re
import os
import struct
import sys
import numbers
from collections import namedtuple, defaultdict
def int_or_float(s):
# return number, trying to maintain int format
if s.isdigit():
return int(s, 10)
else:
return float(s)
DBCSignal = namedtuple(
"DBCSignal", ["name", "start_bit", "size", "is_little_endian", "is_signed",
"factor", "offset", "tmin", "tmax", "units"])
class dbc(object):
def __init__(self, fn):
self.name, _ = os.path.splitext(os.path.basename(fn))
with open(fn) as f:
self.txt = f.readlines()
self._warned_addresses = set()
# regexps from https://github.com/ebroecker/canmatrix/blob/master/canmatrix/importdbc.py
bo_regexp = re.compile(r"^BO\_ (\w+) (\w+) *: (\w+) (\w+)")
sg_regexp = re.compile(r"^SG\_ (\w+) : (\d+)\|(\d+)@(\d+)([\+|\-]) \(([0-9.+\-eE]+),([0-9.+\-eE]+)\) \[([0-9.+\-eE]+)\|([0-9.+\-eE]+)\] \"(.*)\" (.*)")
sgm_regexp = re.compile(r"^SG\_ (\w+) (\w+) *: (\d+)\|(\d+)@(\d+)([\+|\-]) \(([0-9.+\-eE]+),([0-9.+\-eE]+)\) \[([0-9.+\-eE]+)\|([0-9.+\-eE]+)\] \"(.*)\" (.*)")
val_regexp = re.compile(r"VAL\_ (\w+) (\w+) (\s*[-+]?[0-9]+\s+\".+?\"[^;]*)")
# A dictionary which maps message ids to tuples ((name, size), signals).
# name is the ASCII name of the message.
# size is the size of the message in bytes.
# signals is a list signals contained in the message.
# signals is a list of DBCSignal in order of increasing start_bit.
self.msgs = {}
# A dictionary which maps message ids to a list of tuples (signal name, definition value pairs)
self.def_vals = defaultdict(list)
# lookup to bit reverse each byte
self.bits_index = [(i & ~0b111) + ((-i-1) & 0b111) for i in xrange(64)]
for l in self.txt:
l = l.strip()
if l.startswith("BO_ "):
# new group
dat = bo_regexp.match(l)
if dat is None:
print("bad BO {0}".format(l))
name = dat.group(2)
size = int(dat.group(3))
ids = int(dat.group(1), 0) # could be hex
if ids in self.msgs:
sys.exit("Duplicate address detected %d %s" % (ids, self.name))
self.msgs[ids] = ((name, size), [])
if l.startswith("SG_ "):
# new signal
dat = sg_regexp.match(l)
go = 0
if dat is None:
dat = sgm_regexp.match(l)
go = 1
if dat is None:
print("bad SG {0}".format(l))
sgname = dat.group(1)
start_bit = int(dat.group(go+2))
signal_size = int(dat.group(go+3))
is_little_endian = int(dat.group(go+4))==1
is_signed = dat.group(go+5)=='-'
factor = int_or_float(dat.group(go+6))
offset = int_or_float(dat.group(go+7))
tmin = int_or_float(dat.group(go+8))
tmax = int_or_float(dat.group(go+9))
units = dat.group(go+10)
self.msgs[ids][1].append(
DBCSignal(sgname, start_bit, signal_size, is_little_endian,
is_signed, factor, offset, tmin, tmax, units))
if l.startswith("VAL_ "):
# new signal value/definition
dat = val_regexp.match(l)
if dat is None:
print("bad VAL {0}".format(l))
ids = int(dat.group(1), 0) # could be hex
sgname = dat.group(2)
defvals = dat.group(3)
defvals = defvals.replace("?",r"\?") #escape sequence in C++
defvals = defvals.split('"')[:-1]
defs = defvals[1::2]
#cleanup, convert to UPPER_CASE_WITH_UNDERSCORES
for i,d in enumerate(defs):
d = defs[i].strip().upper()
defs[i] = d.replace(" ","_")
defvals[1::2] = defs
defvals = '"'+"".join(str(i) for i in defvals)+'"'
self.def_vals[ids].append((sgname, defvals))
for msg in self.msgs.values():
msg[1].sort(key=lambda x: x.start_bit)
self.msg_name_to_address = {}
for address, m in self.msgs.items():
name = m[0][0]
self.msg_name_to_address[name] = address
def lookup_msg_id(self, msg_id):
if not isinstance(msg_id, numbers.Number):
msg_id = self.msg_name_to_address[msg_id]
return msg_id
def reverse_bytes(self, x):
return ((x & 0xff00000000000000) >> 56) | \
((x & 0x00ff000000000000) >> 40) | \
((x & 0x0000ff0000000000) >> 24) | \
((x & 0x000000ff00000000) >> 8) | \
((x & 0x00000000ff000000) << 8) | \
((x & 0x0000000000ff0000) << 24) | \
((x & 0x000000000000ff00) << 40) | \
((x & 0x00000000000000ff) << 56)
def encode(self, msg_id, dd):
"""Encode a CAN message using the dbc.
Inputs:
msg_id: The message ID.
dd: A dictionary mapping signal name to signal data.
"""
msg_id = self.lookup_msg_id(msg_id)
msg_def = self.msgs[msg_id]
size = msg_def[0][1]
result = 0
for s in msg_def[1]:
ival = dd.get(s.name)
if ival is not None:
b2 = s.size
if s.is_little_endian:
b1 = s.start_bit
else:
b1 = (s.start_bit // 8) * 8 + (-s.start_bit - 1) % 8
bo = 64 - (b1 + s.size)
ival = (ival / s.factor) - s.offset
ival = int(round(ival))
if s.is_signed and ival < 0:
ival = (1 << b2) + ival
shift = b1 if s.is_little_endian else bo
mask = ((1 << b2) - 1) << shift
dat = (ival & ((1 << b2) - 1)) << shift
if s.is_little_endian:
mask = self.reverse_bytes(mask)
dat = self.reverse_bytes(dat)
result &= ~mask
result |= dat
result = struct.pack('>Q', result)
return result[:size]
def decode(self, x, arr=None, debug=False):
"""Decode a CAN message using the dbc.
Inputs:
x: A collection with elements (address, time, data), where address is
the CAN address, time is the bus time, and data is the CAN data as a
hex string.
arr: Optional list of signals which should be decoded and returned.
debug: True to print debugging statements.
Returns:
A tuple (name, data), where name is the name of the CAN message and data
is the decoded result. If arr is None, data is a dict of properties.
Otherwise data is a list of the same length as arr.
Returns (None, None) if the message could not be decoded.
"""
if arr is None:
out = {}
else:
out = [None]*len(arr)
msg = self.msgs.get(x[0])
if msg is None:
if x[0] not in self._warned_addresses:
#print("WARNING: Unknown message address {}".format(x[0]))
self._warned_addresses.add(x[0])
return None, None
name = msg[0][0]
if debug:
print(name)
st = x[2].ljust(8, '\x00')
le, be = None, None
for s in msg[1]:
if arr is not None and s[0] not in arr:
continue
start_bit = s[1]
signal_size = s[2]
little_endian = s[3]
signed = s[4]
factor = s[5]
offset = s[6]
b2 = signal_size
if little_endian:
b1 = start_bit
else:
b1 = (start_bit // 8) * 8 + (-start_bit - 1) % 8
bo = 64 - (b1 + signal_size)
if little_endian:
if le is None:
le = struct.unpack("<Q", st)[0]
shift_amount = b1
tmp = le
else:
if be is None:
be = struct.unpack(">Q", st)[0]
shift_amount = bo
tmp = be
if shift_amount < 0:
continue
tmp = (tmp >> shift_amount) & ((1 << b2) - 1)
if signed and (tmp >> (b2 - 1)):
tmp -= (1 << b2)
tmp = tmp * factor + offset
# if debug:
# print("%40s %2d %2d %7.2f %s" % (s[0], s[1], s[2], tmp, s[-1]))
if arr is None:
out[s[0]] = tmp
else:
out[arr.index(s[0])] = tmp
return name, out
def get_signals(self, msg):
msg = self.lookup_msg_id(msg)
return [sgs.name for sgs in self.msgs[msg][1]]
if __name__ == "__main__":
from opendbc import DBC_PATH
import numpy as np
dbc_test = dbc(os.path.join(DBC_PATH, 'toyota_prius_2017_pt_generated.dbc'))
msg = ('STEER_ANGLE_SENSOR', {'STEER_ANGLE': -6.0, 'STEER_RATE': 4, 'STEER_FRACTION': -0.2})
encoded = dbc_test.encode(*msg)
decoded = dbc_test.decode((0x25, 0, encoded))
assert decoded == msg
dbc_test = dbc(os.path.join(DBC_PATH, 'hyundai_santa_fe_2019_ccan.dbc'))
decoded = dbc_test.decode((0x2b0, 0, "\xfa\xfe\x00\x07\x12"))
assert np.isclose(decoded[1]['SAS_Angle'], -26.2)
msg = ('SAS11', {'SAS_Stat': 7.0, 'MsgCount': 0.0, 'SAS_Angle': -26.200000000000003, 'SAS_Speed': 0.0, 'CheckSum': 0.0})
encoded = dbc_test.encode(*msg)
decoded = dbc_test.decode((0x2b0, 0, encoded))
assert decoded == msg