# -*- coding: utf-8 -*- #! /usr/bin/env python3 import crcmod.predefined
class crc16: def __init__(self): pass
def crc16Modbus(self, bytes_data, start_pos, stop_pos, invert=False): a = 0xFFFF b = 0xA001 for i in range(start_pos, stop_pos): a ^= bytes_data[i] for j in range(8): last = a % 2 a >>= 1 if last == 1: a ^= b return (a << 8 & 0xff00) | a >> 8 if invert == False else a def crc16Modbus2(self, bytes_data, start_pos, stop_pos, invert=False): data = bytes_data[start_pos:stop_pos] modus_crc_func = crcmod.predefined.mkCrcFun('modbus') res = modus_crc_func(data) return (res << 8 & 0xff00) | res >> 8 if invert == False else res def crc16Xmodem(self, bytes_data, start_pos, stop_pos, invert=False): wcrc = 0 for i in range(start_pos, stop_pos): data = bytes_data[i] for j in range(8): treat = data & 0x80 data <<= 1 bcrc = (wcrc >> 8) & 0x80 wcrc <<= 1 wcrc = wcrc & 0xffff if (treat != bcrc): wcrc ^= 0x1021 return wcrc if invert == False else (wcrc << 8 & 0xff00) | wcrc >> 8
def crc16Xmodem2(self, bytes_data, start_pos, stop_pos, invert=False): data = bytes_data[start_pos:stop_pos] xmodem_crc_func = crcmod.predefined.mkCrcFun('xmodem') res = xmodem_crc_func(data) return res if invert == False else (res << 8 & 0xff00) | res >> 8
# debug type: singel file # file name: mycrc16.py # file version: v0.0 # debug time: 2020.8.26 if __name__ == '__main__': crc16_test = crc16() print(hex(crc16_test.crc16Modbus(bytes('123456789', encoding='utf8'), 0, 9))) print(hex(crc16_test.crc16Modbus2(bytes('123456789', encoding='utf8'), 0, 9))) print(hex(crc16_test.crc16Xmodem(bytes('123456789', encoding='utf8'), 0, 9))) print(hex(crc16_test.crc16Xmodem2(bytes('123456789', encoding='utf8'), 0, 9)))
''' 注意： 参数说明 入参：bytes_data 待校验字节串数据, start_pos 校验数据起始位置 stop_pos 校验数据结束位置 invert=False 校验结果默认低字节在前，如果invert=True则高字节在前 出参： 输出2个字节的校验结果 crc16Modbus是自己实现， crc16Modbus2是调用库实现； crc16Xmodem2是自己实现， crc16Xmodem2是调用库实现； '''
