-
Notifications
You must be signed in to change notification settings - Fork 32
/
crc16_python.py
96 lines (83 loc) · 4.25 KB
/
crc16_python.py
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
"""
Computes CRC16
Ref: https://gist.github.com/oysstu/68072c44c02879a2abf94ef350d1c7c6?permalink_comment_id=3943460#gistcomment-3943460
"""
from unittest import TestCase
import logging
def crc16(data: bytes):
'''
CRC-16 (CCITT) implemented with a precomputed lookup table
'''
table = [
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7, 0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6, 0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485, 0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4, 0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823, 0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12, 0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41, 0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70, 0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F, 0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E, 0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D, 0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C, 0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB, 0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A, 0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9, 0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8, 0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
]
crc = 0x0
for byte in data:
crc = ((crc<<8)&0xff00) ^ table[((crc>>8)&0xff)^byte]
return crc & 0xffff
def crc16_str_swap(val: str):
"""
Custom function to compute the CRC16 of a string of hexadecimal data
Params
--
val [str] String of hexadecimal values
Returns
--
crc_str [str] string of 4 charcaters representing 2 bytes of crc16, in swaped order.
"""
LOG_FORMAT='%(asctime)s [CRC16PYTHON::%(funcName)s] [%(levelname)s]:\t%(message)s'
logging.basicConfig(format=LOG_FORMAT, level=logging.INFO)
log = logging.getLogger(__name__)
crc_str = ""
if not isinstance(val, str):
log.error("Message is not string")
return crc_str
b = bytes.fromhex(val)
crc_int = crc16(b)
crc_str = format(crc_int, 'x')
# Just a sanity check:
if len(crc_str)>4:
crc_str='ffff'
return crc_str
# Make sure crc is 4 chatracters (2 for each byte) with swaped bytes
if len(crc_str)==3:
crc_str = "0"+crc_str
if len(crc_str)==2:
crc_str='00'+crc_str
if len(crc_str)==1:
crc_str='000'+crc_str
# Reverse bytes, according to SIYI SDK
low_byte = crc_str[2:]
high_byte = crc_str[0:2]
# swap bytes
crc_str = low_byte+high_byte
return(crc_str)
def crc16_test():
LOG_FORMAT='%(asctime)s [CRC16PYTHON::%(funcName)s] [%(levelname)s]:\t%(message)s'
logging.basicConfig(format=LOG_FORMAT, level=logging.INFO)
log = logging.getLogger(__name__)
data="5566010100000005FF"
expected_crc = "5c6a"
data_crc = crc16_str_swap(data)
log.info("data_crc %s", data_crc)
if data_crc != expected_crc:
log.error("CRC16 of data %s did not match expected CRC %s", data_crc, expected_crc)
else:
log.info("CRC16 Pass!")
if __name__=="__main__":
crc16_test()