"""
ModbusLink LRC校验工具模块
ModbusLink LRC Checksum Utils Module
"""
from typing import Union
[docs]
class LRCModbus:
"""
Modbus LRC校验工具类
Modbus LRC Check Utils Module
"""
[docs]
@staticmethod
def calculate(data: Union[bytes, bytearray]) -> bytes:
"""
计算LRC校验码
Calculate LRC Checksum
Args:
data: 需要计算的数据（不包含起始符':'和结束符CRLF） | Data to calculate (excluding start ':' and end CRLF)
Returns:
bytes: 1字节的LRC校验码 (0x00 - 0xFF)
1-byte LRC checksum (0x00 - 0xFF)
"""
if not data:
return b'\x00'
# 1. 累加所有字节 | Sum all bytes
total = sum(data)
# 2. 取模 0xFF (保留低8位) | Modulo 0xFF (Keep lower 8 bits)
total &= 0xFF
# 3. 取补码 (Two's complement)
# 方式: (0x100 - total) & 0xFF
# 或者: ((total ^ 0xFF) + 1) & 0xFF
lrc = (0x100 - total) & 0xFF
return bytes([lrc])
[docs]
@staticmethod
def validate(data_with_lrc: Union[bytes, bytearray]) -> bool:
"""
验证包含LRC的数据
Validate data with LRC
Args:
data_with_lrc: 包含LRC的完整二进制数据 | Complete binary data containing LRC
Returns:
bool: 校验是否通过
Whether verification passed
"""
if len(data_with_lrc) < 2:
return False
# 方法1：重新计算对比
# Method 1: Recalculate and compare
# data = data_with_lrc[:-1]
# received_lrc = data_with_lrc[-1]
# return LRCModbus.calculate(data) == received_lrc
# 方法2：利用数学特性（所有字节+LRC 的和，模256应为0）
# Method 2: Use mathematical property (Sum of all bytes + LRC, modulo 256 should be 0)
return (sum(data_with_lrc) & 0xFF) == 0