Skip to content
Navigation Menu
{{ message }}
forked from hardbyte/python-can
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathmessage.py
More file actions
331 lines (280 loc) · 11.7 KB
/
Copy pathmessage.py
File metadata and controls
331 lines (280 loc) · 11.7 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
"""
This module contains the implementation of :class:`can.Message`.
.. note::
Could use `@dataclass <https://docs.python.org/3.7/library/dataclasses.html>`__
starting with Python 3.7.
"""
from typing import Optional
from . import typechecking
from copy import deepcopy
from math import isinf, isnan
class Message: # pylint: disable=too-many-instance-attributes; OK for a dataclass
"""
The :class:`~can.Message` object is used to represent CAN messages for
sending, receiving and other purposes like converting between different
logging formats.
Messages can use extended identifiers, be remote or error frames, contain
data and may be associated to a channel.
Messages are always compared by identity and never by value, because that
may introduce unexpected behaviour. See also :meth:`~can.Message.equals`.
:func:`~copy.copy`/:func:`~copy.deepcopy` is supported as well.
Messages do not support "dynamic" attributes, meaning any others than the
documented ones, since it uses :obj:`~object.__slots__`.
"""
__slots__ = (
"timestamp",
"arbitration_id",
"is_extended_id",
"is_remote_frame",
"is_error_frame",
"channel",
"dlc",
"data",
"is_fd",
"is_rx",
"bitrate_switch",
"error_state_indicator",
"__weakref__", # support weak references to messages
)
def __init__( # pylint: disable=too-many-locals, too-many-arguments
self,
timestamp: float = 0.0,
arbitration_id: int = 0,
is_extended_id: bool = True,
is_remote_frame: bool = False,
is_error_frame: bool = False,
channel: Optional[typechecking.Channel] = None,
dlc: Optional[int] = None,
data: Optional[typechecking.CanData] = None,
is_fd: bool = False,
is_rx: bool = True,
bitrate_switch: bool = False,
error_state_indicator: bool = False,
check: bool = False,
):
"""
To create a message object, simply provide any of the below attributes
together with additional parameters as keyword arguments to the constructor.
:param check: By default, the constructor of this class does not strictly check the input.
Thus, the caller must prevent the creation of invalid messages or
set this parameter to `True`, to raise an Error on invalid inputs.
Possible problems include the `dlc` field not matching the length of `data`
or creating a message with both `is_remote_frame` and `is_error_frame` set
to `True`.
:raises ValueError:
If and only if `check` is set to `True` and one or more arguments were invalid
"""
self.timestamp = timestamp
self.arbitration_id = arbitration_id
self.is_extended_id = is_extended_id
self.is_remote_frame = is_remote_frame
self.is_error_frame = is_error_frame
self.channel = channel
self.is_fd = is_fd
self.is_rx = is_rx
self.bitrate_switch = bitrate_switch
self.error_state_indicator = error_state_indicator
if data is None or is_remote_frame:
self.data = bytearray()
elif isinstance(data, bytearray):
self.data = data
else:
try:
self.data = bytearray(data)
except TypeError as error:
err = f"Couldn't create message from {data} ({type(data)})"
raise TypeError(err) from error
if dlc is None:
self.dlc = len(self.data)
else:
self.dlc = dlc
if check:
self._check()
def __str__(self) -> str:
field_strings = [f"Timestamp: {self.timestamp:>15.6f}"]
if self.is_extended_id:
arbitration_id_string = f"ID: {self.arbitration_id:08x}"
else:
arbitration_id_string = f"ID: {self.arbitration_id:04x}"
field_strings.append(arbitration_id_string.rjust(12, " "))
flag_string = " ".join(
[
"X" if self.is_extended_id else "S",
"Rx" if self.is_rx else "Tx",
"E" if self.is_error_frame else " ",
"R" if self.is_remote_frame else " ",
"F" if self.is_fd else " ",
"BS" if self.bitrate_switch else " ",
"EI" if self.error_state_indicator else " ",
]
)
field_strings.append(flag_string)
field_strings.append(f"DL: {self.dlc:2d}")
data_strings = []
if self.data is not None:
for index in range(0, min(self.dlc, len(self.data))):
data_strings.append(f"{self.data[index]:02x}")
if data_strings: # if not empty
field_strings.append(" ".join(data_strings).ljust(24, " "))
else:
field_strings.append(" " * 24)
if (self.data is not None) and (self.data.isalnum()):
field_strings.append(f"'{self.data.decode('utf-8', 'replace')}'")
if self.channel is not None:
try:
field_strings.append(f"Channel: {self.channel}")
except UnicodeEncodeError:
pass
return " ".join(field_strings).strip()
def __len__(self) -> int:
# return the dlc such that it also works on remote frames
return self.dlc
def __bool__(self) -> bool:
return True
def __repr__(self) -> str:
args = [
f"timestamp={self.timestamp}",
f"arbitration_id={self.arbitration_id:#x}",
f"is_extended_id={self.is_extended_id}",
]
if not self.is_rx:
args.append("is_rx=False")
if self.is_remote_frame:
args.append(f"is_remote_frame={self.is_remote_frame}")
if self.is_error_frame:
args.append(f"is_error_frame={self.is_error_frame}")
if self.channel is not None:
args.append(f"channel={self.channel!r}")
data = [f"{byte:#02x}" for byte in self.data]
args += [f"dlc={self.dlc}", f"data=[{', '.join(data)}]"]
if self.is_fd:
args.append("is_fd=True")
args.append(f"bitrate_switch={self.bitrate_switch}")
args.append(f"error_state_indicator={self.error_state_indicator}")
return f"can.Message({', '.join(args)})"
def __format__(self, format_spec: Optional[str]) -> str:
if not format_spec:
return self.__str__()
else:
raise ValueError("non-empty format_specs are not supported")
def __bytes__(self) -> bytes:
return bytes(self.data)
def __copy__(self) -> "Message":
return Message(
timestamp=self.timestamp,
arbitration_id=self.arbitration_id,
is_extended_id=self.is_extended_id,
is_remote_frame=self.is_remote_frame,
is_error_frame=self.is_error_frame,
channel=self.channel,
dlc=self.dlc,
data=self.data,
is_fd=self.is_fd,
is_rx=self.is_rx,
bitrate_switch=self.bitrate_switch,
error_state_indicator=self.error_state_indicator,
)
def __deepcopy__(self, memo: dict) -> "Message":
return Message(
timestamp=self.timestamp,
arbitration_id=self.arbitration_id,
is_extended_id=self.is_extended_id,
is_remote_frame=self.is_remote_frame,
is_error_frame=self.is_error_frame,
channel=deepcopy(self.channel, memo),
dlc=self.dlc,
data=deepcopy(self.data, memo),
is_fd=self.is_fd,
is_rx=self.is_rx,
bitrate_switch=self.bitrate_switch,
error_state_indicator=self.error_state_indicator,
)
def _check(self) -> None:
"""Checks if the message parameters are valid.
Assumes that the attribute types are already correct.
:raises ValueError: If and only if one or more attributes are invalid
"""
if self.timestamp < 0.0:
raise ValueError("the timestamp may not be negative")
if isinf(self.timestamp):
raise ValueError("the timestamp may not be infinite")
if isnan(self.timestamp):
raise ValueError("the timestamp may not be NaN")
if self.is_remote_frame:
if self.is_error_frame:
raise ValueError(
"a message cannot be a remote and an error frame at the sane time"
)
if self.is_fd:
raise ValueError("CAN FD does not support remote frames")
if self.arbitration_id < 0:
raise ValueError("arbitration IDs may not be negative")
if self.is_extended_id:
if self.arbitration_id >= 0x20000000:
raise ValueError("Extended arbitration IDs must be less than 2^29")
elif self.arbitration_id >= 0x800:
raise ValueError("Normal arbitration IDs must be less than 2^11")
if self.dlc < 0:
raise ValueError("DLC may not be negative")
if self.is_fd:
if self.dlc > 64:
raise ValueError(
f"DLC was {self.dlc} but it should be <= 64 for CAN FD frames"
)
elif self.dlc > 8:
raise ValueError(
f"DLC was {self.dlc} but it should be <= 8 for normal CAN frames"
)
if self.is_remote_frame:
if self.data:
raise ValueError("remote frames may not carry any data")
elif self.dlc != len(self.data):
raise ValueError(
"the DLC and the length of the data must match up for non remote frames"
)
if not self.is_fd:
if self.bitrate_switch:
raise ValueError("bitrate switch is only allowed for CAN FD frames")
if self.error_state_indicator:
raise ValueError(
"error state indicator is only allowed for CAN FD frames"
)
def equals(
self,
other: "Message",
timestamp_delta: Optional[float] = 1.0e-6,
check_direction: bool = True,
) -> bool:
"""
Compares a given message with this one.
:param other: the message to compare with
:param timestamp_delta: the maximum difference in seconds at which two timestamps are
still considered equal or `None` to not compare timestamps
:param check_direction: whether to compare the messages' directions (Tx/Rx)
:return: True if and only if the given message equals this one
"""
# see https://github.com/hardbyte/python-can/pull/413 for a discussion
# on why a delta of 1.0e-6 was chosen
return (
# check for identity first and finish fast
self is other
or
# then check for equality by value
(
(
timestamp_delta is None
or abs(self.timestamp - other.timestamp) <= timestamp_delta
)
and (self.is_rx == other.is_rx or not check_direction)
and self.arbitration_id == other.arbitration_id
and self.is_extended_id == other.is_extended_id
and self.dlc == other.dlc
and self.data == other.data
and self.is_remote_frame == other.is_remote_frame
and self.is_error_frame == other.is_error_frame
and self.channel == other.channel
and self.is_fd == other.is_fd
and self.bitrate_switch == other.bitrate_switch
and self.error_state_indicator == other.error_state_indicator
)
)
You can’t perform that action at this time.