jyoung/selfdrive/can/packer.py

import struct
from selfdrive.can.libdbc_py import libdbc, ffi


class CANPacker(object):
  def __init__(self, dbc_name):
    self.packer = libdbc.canpack_init(dbc_name)
    self.dbc = libdbc.dbc_lookup(dbc_name)
    self.sig_names = {}
    self.name_to_address_and_size = {}

    num_msgs = self.dbc[0].num_msgs
    for i in range(num_msgs):
      msg = self.dbc[0].msgs[i]

      name = ffi.string(msg.name)
      address = msg.address
      self.name_to_address_and_size[name] = (address, msg.size)
      self.name_to_address_and_size[address] = (address, msg.size)

  def pack(self, addr, values, counter):
    values_thing = []
    for name, value in values.items():
      if name not in self.sig_names:
        self.sig_names[name] = ffi.new("char[]", name)

      values_thing.append({
        'name': self.sig_names[name],
        'value': value
      })

    values_c = ffi.new("SignalPackValue[]", values_thing)

    return libdbc.canpack_pack(self.packer, addr, len(values_thing), values_c, counter)

  def pack_bytes(self, addr, values, counter=-1):
    addr, size = self.name_to_address_and_size[addr]

    val = self.pack(addr, values, counter)
    r = struct.pack(">Q", val)
    return addr, r[:size]

  def make_can_msg(self, addr, bus, values, counter=-1):
    addr, msg = self.pack_bytes(addr, values, counter)
    return [addr, 0, msg, bus]


if __name__ == "__main__":
  ## little endian test
  cp = CANPacker("hyundai_santa_fe_2019_ccan")
  s = cp.pack_bytes(0x340, {
    "CR_Lkas_StrToqReq": -0.06,
    #"CF_Lkas_FcwBasReq": 1,
    "CF_Lkas_MsgCount": 7,
    "CF_Lkas_HbaSysState": 0,
    #"CF_Lkas_Chksum": 3,
  })
  s = cp.pack_bytes(0x340, {
    "CF_Lkas_MsgCount": 1,
  })
  # big endian test
  #cp = CANPacker("honda_civic_touring_2016_can_generated")
  #s = cp.pack_bytes(0xe4, {
  #  "STEER_TORQUE": -2,
  #})
  print([hex(ord(v)) for v in s[1]])
  print(s[1].encode("hex"))