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220 lines
6.5 KiB
220 lines
6.5 KiB
import re
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import os
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import struct
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import bitstring
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import sys
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import numbers
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from collections import namedtuple
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def int_or_float(s):
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# return number, trying to maintain int format
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try:
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return int(s)
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except ValueError:
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return float(s)
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DBCSignal = namedtuple(
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"DBCSignal", ["name", "start_bit", "size", "is_little_endian", "is_signed",
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"factor", "offset", "tmin", "tmax", "units"])
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class dbc(object):
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def __init__(self, fn):
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self.name, _ = os.path.splitext(os.path.basename(fn))
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with open(fn) as f:
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self.txt = f.read().split("\n")
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self._warned_addresses = set()
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# regexps from https://github.com/ebroecker/canmatrix/blob/master/canmatrix/importdbc.py
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bo_regexp = re.compile("^BO\_ (\w+) (\w+) *: (\w+) (\w+)")
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sg_regexp = re.compile("^SG\_ (\w+) : (\d+)\|(\d+)@(\d+)([\+|\-]) \(([0-9.+\-eE]+),([0-9.+\-eE]+)\) \[([0-9.+\-eE]+)\|([0-9.+\-eE]+)\] \"(.*)\" (.*)")
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sgm_regexp = re.compile("^SG\_ (\w+) (\w+) *: (\d+)\|(\d+)@(\d+)([\+|\-]) \(([0-9.+\-eE]+),([0-9.+\-eE]+)\) \[([0-9.+\-eE]+)\|([0-9.+\-eE]+)\] \"(.*)\" (.*)")
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# A dictionary which maps message ids to tuples ((name, size), signals).
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# name is the ASCII name of the message.
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# size is the size of the message in bytes.
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# signals is a list signals contained in the message.
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# signals is a list of DBCSignal in order of increasing start_bit.
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self.msgs = {}
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# lookup to bit reverse each byte
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self.bits_index = [(i & ~0b111) + ((-i-1) & 0b111) for i in xrange(64)]
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for l in self.txt:
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l = l.strip()
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if l.startswith("BO_ "):
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# new group
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dat = bo_regexp.match(l)
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if dat is None:
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print "bad BO", l
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name = dat.group(2)
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size = int(dat.group(3))
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ids = int(dat.group(1), 0) # could be hex
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if ids in self.msgs:
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sys.exit("Duplicate address detected %d %s" % (ids, self.name))
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self.msgs[ids] = ((name, size), [])
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if l.startswith("SG_ "):
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# new signal
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dat = sg_regexp.match(l)
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go = 0
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if dat is None:
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dat = sgm_regexp.match(l)
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go = 1
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if dat is None:
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print "bad SG", l
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sgname = dat.group(1)
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start_bit = int(dat.group(go+2))
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signal_size = int(dat.group(go+3))
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is_little_endian = int(dat.group(go+4))==1
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is_signed = dat.group(go+5)=='-'
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factor = int_or_float(dat.group(go+6))
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offset = int_or_float(dat.group(go+7))
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tmin = int_or_float(dat.group(go+8))
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tmax = int_or_float(dat.group(go+9))
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units = dat.group(go+10)
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self.msgs[ids][1].append(
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DBCSignal(sgname, start_bit, signal_size, is_little_endian,
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is_signed, factor, offset, tmin, tmax, units))
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for msg in self.msgs.viewvalues():
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msg[1].sort(key=lambda x: x.start_bit)
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self.msg_name_to_address = {}
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for address, m in self.msgs.items():
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name = m[0][0]
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self.msg_name_to_address[name] = address
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def lookup_msg_id(self, msg_id):
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if not isinstance(msg_id, numbers.Number):
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msg_id = self.msg_name_to_address[msg_id]
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return msg_id
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def encode(self, msg_id, dd):
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"""Encode a CAN message using the dbc.
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Inputs:
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msg_id: The message ID.
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dd: A dictionary mapping signal name to signal data.
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"""
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msg_id = self.lookup_msg_id(msg_id)
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# TODO: Stop using bitstring, which is super slow.
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msg_def = self.msgs[msg_id]
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size = msg_def[0][1]
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bsf = bitstring.Bits(hex="00"*size)
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for s in msg_def[1]:
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ival = dd.get(s.name)
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if ival is not None:
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ival = (ival / s.factor) - s.offset
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ival = int(round(ival))
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# should pack this
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if s.is_little_endian:
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ss = s.start_bit
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else:
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ss = self.bits_index[s.start_bit]
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if s.is_signed:
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tbs = bitstring.Bits(int=ival, length=s.size)
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else:
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tbs = bitstring.Bits(uint=ival, length=s.size)
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lpad = bitstring.Bits(bin="0b"+"0"*ss)
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rpad = bitstring.Bits(bin="0b"+"0"*(8*size-(ss+s.size)))
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tbs = lpad+tbs+rpad
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bsf |= tbs
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return bsf.tobytes()
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def decode(self, x, arr=None, debug=False):
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"""Decode a CAN message using the dbc.
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Inputs:
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x: A collection with elements (address, time, data), where address is
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the CAN address, time is the bus time, and data is the CAN data as a
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hex string.
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arr: Optional list of signals which should be decoded and returned.
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debug: True to print debugging statements.
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Returns:
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A tuple (name, data), where name is the name of the CAN message and data
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is the decoded result. If arr is None, data is a dict of properties.
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Otherwise data is a list of the same length as arr.
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Returns (None, None) if the message could not be decoded.
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"""
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if arr is None:
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out = {}
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else:
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out = [None]*len(arr)
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msg = self.msgs.get(x[0])
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if msg is None:
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if x[0] not in self._warned_addresses:
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#print("WARNING: Unknown message address {}".format(x[0]))
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self._warned_addresses.add(x[0])
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return None, None
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name = msg[0][0]
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if debug:
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print name
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blen = 8*len(x[2])
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st = x[2].rjust(8, '\x00')
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le, be = None, None
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for s in msg[1]:
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if arr is not None and s[0] not in arr:
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continue
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# big or little endian?
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# see http://vi-firmware.openxcplatform.com/en/master/config/bit-numbering.html
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if s[3] is False:
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ss = self.bits_index[s[1]]
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if be is None:
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be = struct.unpack(">Q", st)[0]
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x2_int = be
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data_bit_pos = (blen - (ss + s[2]))
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else:
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if le is None:
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le = struct.unpack("<Q", st)[0]
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x2_int = le
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ss = s[1]
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data_bit_pos = ss
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if data_bit_pos < 0:
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continue
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ival = (x2_int >> data_bit_pos) & ((1 << (s[2])) - 1)
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if s[4] and (ival & (1<<(s[2]-1))): # signed
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ival -= (1<<s[2])
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# control the offset
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ival = (ival * s[5]) + s[6]
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#if debug:
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# print "%40s %2d %2d %7.2f %s" % (s[0], s[1], s[2], ival, s[-1])
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if arr is None:
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out[s[0]] = ival
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else:
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out[arr.index(s[0])] = ival
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return name, out
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def get_signals(self, msg):
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msg = self.lookup_msg_id(msg)
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return [sgs.name for sgs in self.msgs[msg][1]]
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if __name__ == "__main__":
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from opendbc import DBC_PATH
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dbc_test = dbc(os.path.join(DBC_PATH, sys.argv[1]))
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print dbc_test.get_signals(0xe4)
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