CODEWITHSUNDEEP
pythonpython-3.xcrccrc32
sstevan
sstevan

Reputation: 487

Calculate CRC-CCITT (0xFFFF) for HEX string

I'm trying to calulate CRC-CCITT (0xFFFF) for HEX string and get result back as HEX string. I tried binascii and crc16 but I get int values and when I convert them to HEX it's not the value I expected. I need this:

hex_string = "AA01"
crc_string = crccitt(hex_string)
print("CRC: ", crc_string)

>>> CRC: FF9B

Upvotes: 1

Views: 6679

Answers (1)

falsetru
falsetru

Reputation: 368894

You can use str.format / format to convert the int value to hexadecimal format: (used crc16 to get crc)

>>> import binascii
>>> import crc16
>>> hex_string = 'AA01'
>>> crc = crc16.crc16xmodem(binascii.unhexlify(hex_string), 0xffff)
>>> '{:04X}'.format(crc & 0xffff)
'FF9B'
>>> format(crc & 0xffff, '04X')
'FF9B'

or using % operator:

>>> '%04X' % (crc & 0xffff)
'FF9B'

import binascii
import crc16

def crccitt(hex_string):
    byte_seq = binascii.unhexlify(hex_string)
    crc = crc16.crc16xmodem(byte_seq, 0xffff)
    return '{:04X}'.format(crc & 0xffff)

Upvotes: 2

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