# Copyright (C) 2018 Kristian Sloth Lauszus. # # This program is free software; you can redistribute it and/or # modify it under the terms of the GNU Lesser General Public # License as published by the Free Software Foundation; either # version 3 of the License, or (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public License # along with this program; if not, write to the Free Software Foundation, # Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. # # Contact information # ------------------- # Kristian Sloth Lauszus # Web : http://www.lauszus.com # e-mail : lauszus@gmail.com import argparse import errno import logging import os import struct import sys import time from typing import Dict, List, Tuple from can import __version__ from can.logger import ( _append_filter_argument, _create_base_argument_parser, _create_bus, _parse_additional_config, ) from can.typechecking import TAdditionalCliArgs, TDataStructs logger = logging.getLogger("can.viewer") try: import curses from curses.ascii import ESC as KEY_ESC # type: ignore[attr-defined,unused-ignore] from curses.ascii import SP as KEY_SPACE # type: ignore[attr-defined,unused-ignore] except ImportError: # Probably on Windows while windows-curses is not installed (e.g. in PyPy) logger.warning( "You won't be able to use the viewer program without curses installed!" ) curses = None # type: ignore[assignment] class CanViewer: # pylint: disable=too-many-instance-attributes def __init__(self, stdscr, bus, data_structs, testing=False): self.stdscr = stdscr self.bus = bus self.data_structs = data_structs # Initialise the ID dictionary, Previous values dict, start timestamp, # scroll and variables for pausing the viewer and enabling byte highlighting self.ids = {} self.start_time = None self.scroll = 0 self.paused = False self.highlight_changed_bytes = False self.previous_values = {} # Get the window dimensions - used for resizing the window self.y, self.x = self.stdscr.getmaxyx() # Do not wait for key inputs, disable the cursor and choose the background color # automatically self.stdscr.nodelay(True) curses.curs_set(0) curses.use_default_colors() # Used to color error frames red curses.init_pair(1, curses.COLOR_RED, -1) # Used to color changed bytes curses.init_pair(2, curses.COLOR_CYAN, curses.COLOR_BLUE) if not testing: # pragma: no cover self.run() def run(self): # Clear the terminal and draw the header self.draw_header() while True: # Do not read the CAN-Bus when in paused mode if not self.paused: # Read the CAN-Bus and draw it in the terminal window msg = self.bus.recv(timeout=1.0 / 1000.0) if msg is not None: self.draw_can_bus_message(msg) else: # Sleep 1 ms, so the application does not use 100 % of the CPU resources time.sleep(1.0 / 1000.0) # Read the terminal input key = self.stdscr.getch() # Stop program if the user presses ESC or 'q' if key == KEY_ESC or key == ord("q"): break # Clear by pressing 'c' if key == ord("c"): self.ids = {} self.start_time = None self.scroll = 0 self.draw_header() # Toggle byte change highlighting pressing 'h' elif key == ord("h"): self.highlight_changed_bytes = not self.highlight_changed_bytes if not self.highlight_changed_bytes: # empty the previous values dict when leaving higlighting mode self.previous_values.clear() self.draw_header() # Sort by pressing 's' elif key == ord("s"): # Sort frames based on the CAN-Bus ID self.draw_header() for i, key in enumerate(sorted(self.ids.keys())): # Set the new row index, but skip the header self.ids[key]["row"] = i + 1 # Do a recursive call, so the frames are repositioned self.draw_can_bus_message(self.ids[key]["msg"], sorting=True) # Pause by pressing space elif key == KEY_SPACE: self.paused = not self.paused # Scroll by pressing up/down elif key == curses.KEY_UP: # Limit scrolling, so the user do not scroll passed the header if self.scroll > 0: self.scroll -= 1 self.redraw_screen() elif key == curses.KEY_DOWN: # Limit scrolling, so the maximum scrolling position is one below the last line if self.scroll <= len(self.ids) - self.y + 1: self.scroll += 1 self.redraw_screen() # Check if screen was resized resized = curses.is_term_resized(self.y, self.x) if resized is True: self.y, self.x = self.stdscr.getmaxyx() if hasattr(curses, "resizeterm"): # pragma: no cover curses.resizeterm(self.y, self.x) self.redraw_screen() # Shutdown the CAN-Bus interface self.bus.shutdown() # Unpack the data and then convert it into SI-units @staticmethod def unpack_data(cmd: int, cmd_to_struct: Dict, data: bytes) -> List[float]: if not cmd_to_struct or not data: # These messages do not contain a data package return [] for key in cmd_to_struct: if cmd == key if isinstance(key, int) else cmd in key: value = cmd_to_struct[key] if isinstance(value, tuple): # The struct is given as the fist argument struct_t: struct.Struct = value[0] # The conversion from raw values to SI-units are given in the rest of the tuple values = [ d // val if isinstance(val, int) else float(d) / val for d, val in zip(struct_t.unpack(data), value[1:]) ] else: # No conversion from SI-units is needed as_struct_t: struct.Struct = value values = list(as_struct_t.unpack(data)) return values raise ValueError(f"Unknown command: 0x{cmd:02X}") def draw_can_bus_message(self, msg, sorting=False): # Use the CAN-Bus ID as the key in the dict key = msg.arbitration_id # Sort the extended IDs at the bottom by setting the 32-bit high if msg.is_extended_id: key |= 1 << 32 new_id_added, length_changed = False, False if not sorting: # Check if it is a new message or if the length is not the same if key not in self.ids: new_id_added = True # Set the start time when the first message has been received if not self.start_time: self.start_time = msg.timestamp elif msg.dlc != self.ids[key]["msg"].dlc: length_changed = True # Clear the old data bytes when the length of the new message is shorter if msg.dlc < self.ids[key]["msg"].dlc: self.draw_line( self.ids[key]["row"], # Start drawing at the last byte that is not in the new message 52 + msg.dlc * 3, # Draw spaces where the old bytes were drawn " " * ((self.ids[key]["msg"].dlc - msg.dlc) * 3 - 1), ) if new_id_added or length_changed: # Increment the index if it was just added, but keep it if the length just changed row = len(self.ids) + 1 if new_id_added else self.ids[key]["row"] # It's a new message ID or the length has changed, so add it to the dict # The first index is the row index, the second is the frame counter, # the third is a copy of the CAN-Bus frame # and the forth index is the time since the previous message self.ids[key] = {"row": row, "count": 0, "msg": msg, "dt": 0} else: # Calculate the time since the last message and save the timestamp self.ids[key]["dt"] = msg.timestamp - self.ids[key]["msg"].timestamp # Copy the CAN-Bus frame - this is used for sorting self.ids[key]["msg"] = msg # Increment frame counter self.ids[key]["count"] += 1 # Format the CAN-Bus ID as a hex value arbitration_id_string = ( "0x{0:0{1}X}".format( # pylint: disable=consider-using-f-string msg.arbitration_id, 8 if msg.is_extended_id else 3, ) ) # Use red for error frames if msg.is_error_frame: color = curses.color_pair(1) else: color = curses.color_pair(0) # Now draw the CAN-Bus message on the terminal window self.draw_line(self.ids[key]["row"], 0, str(self.ids[key]["count"]), color) self.draw_line( self.ids[key]["row"], 8, f"{self.ids[key]['msg'].timestamp - self.start_time:.6f}", color, ) self.draw_line(self.ids[key]["row"], 23, f"{self.ids[key]['dt']:.6f}", color) self.draw_line(self.ids[key]["row"], 35, arbitration_id_string, color) self.draw_line(self.ids[key]["row"], 47, str(msg.dlc), color) try: previous_byte_values = self.previous_values[key] except KeyError: # no row of previous values exists for the current message ID # initialise a row to store the values for comparison next time self.previous_values[key] = {} previous_byte_values = self.previous_values[key] for i, b in enumerate(msg.data): col = 52 + i * 3 if col > self.x - 2: # Data does not fit self.draw_line(self.ids[key]["row"], col - 4, "...", color) break if self.highlight_changed_bytes: try: if b != previous_byte_values[i]: # set colour to highlight a changed value data_color = curses.color_pair(2) else: data_color = color except KeyError: # previous entry for byte didn't exist - default to rest of line colour data_color = color finally: # write the new value to the previous values dict for next time previous_byte_values[i] = b else: data_color = color text = f"{b:02X}" self.draw_line(self.ids[key]["row"], col, text, data_color) if self.data_structs: try: values_list = [] for x in self.unpack_data( msg.arbitration_id, self.data_structs, msg.data ): if isinstance(x, float): values_list.append(f"{x:.6f}") else: values_list.append(str(x)) values_string = " ".join(values_list) self.ids[key]["values_string_length"] = len(values_string) values_string += " " * (self.x - len(values_string)) self.draw_line(self.ids[key]["row"], 77, values_string, color) except (ValueError, struct.error): pass return self.ids[key] def draw_line(self, row, col, txt, *args): if row - self.scroll < 0: # Skip if we have scrolled past the line return try: self.stdscr.addstr(row - self.scroll, col, txt, *args) except curses.error: # Ignore if we are trying to write outside the window # This happens if the terminal window is too small pass def draw_header(self): self.stdscr.erase() self.draw_line(0, 0, "Count", curses.A_BOLD) self.draw_line(0, 8, "Time", curses.A_BOLD) self.draw_line(0, 23, "dt", curses.A_BOLD) self.draw_line(0, 35, "ID", curses.A_BOLD) self.draw_line(0, 47, "DLC", curses.A_BOLD) self.draw_line(0, 52, "Data", curses.A_BOLD) # Indicate that byte change highlighting is enabled if self.highlight_changed_bytes: self.draw_line(0, 57, "(changed)", curses.color_pair(2)) # Only draw if the dictionary is not empty if self.data_structs: self.draw_line(0, 77, "Parsed values", curses.A_BOLD) def redraw_screen(self): # Trigger a complete redraw self.draw_header() for ids in self.ids.values(): self.draw_can_bus_message(ids["msg"]) class SmartFormatter(argparse.HelpFormatter): def _get_default_metavar_for_optional(self, action): return action.dest.upper() def _format_usage(self, usage, actions, groups, prefix): # Use uppercase for "Usage:" text return super()._format_usage(usage, actions, groups, "Usage: ") def _format_args(self, action, default_metavar): if action.nargs not in (argparse.REMAINDER, argparse.ONE_OR_MORE): return super()._format_args(action, default_metavar) # Use the metavar if "REMAINDER" or "ONE_OR_MORE" is set get_metavar = self._metavar_formatter(action, default_metavar) return str(get_metavar(1)) def _format_action_invocation(self, action): if not action.option_strings or action.nargs == 0: return super()._format_action_invocation(action) # Modified so "-s ARGS, --long ARGS" is replaced with "-s, --long ARGS" else: parts = [] default = self._get_default_metavar_for_optional(action) args_string = self._format_args(action, default) for i, option_string in enumerate(action.option_strings): if i == len(action.option_strings) - 1: parts.append(f"{option_string} {args_string}") else: parts.append(str(option_string)) return ", ".join(parts) def _split_lines(self, text, width): # Allow to manually split the lines if text.startswith("R|"): return text[2:].splitlines() return super()._split_lines(text, width) def _fill_text(self, text, width, indent): if text.startswith("R|"): return "".join(indent + line + "\n" for line in text[2:].splitlines()) else: return super()._fill_text(text, width, indent) def _parse_viewer_args( args: List[str], ) -> Tuple[argparse.Namespace, TDataStructs, TAdditionalCliArgs]: # Parse command line arguments parser = argparse.ArgumentParser( "python3 -m can.viewer", description="A simple CAN viewer terminal application written in Python", epilog="R|Shortcuts: " "\n +---------+-------------------------------+" "\n | Key | Description |" "\n +---------+-------------------------------+" "\n | ESQ/q | Exit the viewer |" "\n | c | Clear the stored frames |" "\n | s | Sort the stored frames |" "\n | h | Toggle highlight byte changes |" "\n | SPACE | Pause the viewer |" "\n | UP/DOWN | Scroll the viewer |" "\n +---------+-------------------------------+", formatter_class=SmartFormatter, add_help=False, allow_abbrev=False, ) # Generate the standard arguments: # Channel, bitrate, data_bitrate, interface, app_name, CAN-FD support _create_base_argument_parser(parser) optional = parser.add_argument_group("Optional arguments") optional.add_argument( "-h", "--help", action="help", help="Show this help message and exit" ) optional.add_argument( "--version", action="version", help="Show program's version number and exit", version=f"%(prog)s (version {__version__})", ) optional.add_argument( "-d", "--decode", dest="decode", help="R|Specify how to convert the raw bytes into real values." "\nThe ID of the frame is given as the first argument and the format as the second." "\nThe Python struct package is used to unpack the received data" "\nwhere the format characters have the following meaning:" "\n < = little-endian, > = big-endian" "\n x = pad byte" "\n c = char" "\n ? = bool" "\n b = int8_t, B = uint8_t" "\n h = int16, H = uint16" "\n l = int32_t, L = uint32_t" "\n q = int64_t, Q = uint64_t" "\n f = float (32-bits), d = double (64-bits)" "\nFx to convert six bytes with ID 0x100 into uint8_t, uint16 and uint32_t:" '\n $ python3 -m can.viewer -d "100: = big-endian # x = pad byte # c = char # ? = bool # b = int8_t, B = uint8_t # h = int16, H = uint16 # l = int32_t, L = uint32_t # q = int64_t, Q = uint64_t # f = float (32-bits), d = double (64-bits) # # An optional conversion from real units to integers can be given as additional arguments. # In order to convert from raw integer value the real units are multiplied with the values and # similarly the values # are divided by the value in order to convert from real units to raw integer values. data_structs: TDataStructs = {} if parsed_args.decode: if os.path.isfile(parsed_args.decode[0]): with open(parsed_args.decode[0], encoding="utf-8") as f: structs = f.readlines() else: structs = parsed_args.decode for s in structs: tmp = s.rstrip("\n").split(":") # The ID is given as a hex value, the format needs no conversion key, fmt = int(tmp[0], base=16), tmp[1] # The scaling scaling: List[float] = [] for t in tmp[2:]: # First try to convert to int, if that fails, then convert to a float try: scaling.append(int(t)) except ValueError: scaling.append(float(t)) if scaling: data_structs[key] = (struct.Struct(fmt), *scaling) else: data_structs[key] = struct.Struct(fmt) additional_config = _parse_additional_config( [*parsed_args.extra_args, *unknown_args] ) return parsed_args, data_structs, additional_config def main() -> None: parsed_args, data_structs, additional_config = _parse_viewer_args(sys.argv[1:]) bus = _create_bus(parsed_args, **additional_config) curses.wrapper(CanViewer, bus, data_structs) # type: ignore[attr-defined,unused-ignore] if __name__ == "__main__": # Catch ctrl+c try: main() except KeyboardInterrupt: pass