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# ========================================================================== #
# #
# KVMD - The main PiKVM daemon. #
# #
# Copyright (C) 2018-2022 Maxim Devaev <[email protected]> #
# #
# This program is free software: you can redistribute it and/or modify #
# it under the terms of the GNU 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 General Public License for more details. #
# #
# You should have received a copy of the GNU General Public License #
# along with this program. If not, see <https://www.gnu.org/licenses/>. #
# #
# ========================================================================== #
import serial
# =====
class ChipResponseError(Exception):
pass
# =====
class Chip:
def __init__(self, device_path: str, speed: int, read_timeout: float) -> None:
self.__tty = serial.Serial(device_path, speed, timeout=read_timeout)
self.__device_path = device_path
def xfer(self, cmd: bytes) -> int:
self.__send(cmd)
return self.__recv()
def __send(self, cmd: bytes) -> None:
# RESET = [0x00,0x0F,0x00]
# GET_INFO = [0x00,0x01,0x00]
if len(cmd) == 0:
cmd = b"\x00\x01\x00"
cmd = b"\x57\xAB" + cmd
cmd += self.__make_checksum(cmd).to_bytes()
self.__tty.write(serial.to_bytes(cmd))
def __recv(self) -> int:
data = self.__tty.read(5)
if len(data) < 5:
raise ChipResponseError("Too short response, HID might be disconnected")
if data and data[4]:
data += self.__tty.read(data[4] + 1)
if self.__make_checksum(data[:-1]) != data[-1]:
raise ChipResponseError("Invalid response checksum")
if data[4] == 1 and data[5] != 0:
raise ChipResponseError(f"Response error code = {data[5]!r}")
# led_byte (info) response
return (data[7] if data[3] == 0x81 else -1)
def __make_checksum(self, cmd: bytes) -> int:
return (sum(cmd) % 256)
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