4-Bit CRC Algorithm Conversion

[LV2019_Newb]

Hello,

I am very new to programming in LabVIEW and have been tasked with writing an algorithm in LabView2019 that uses the polynomial 0x13 (x^4+x^1+1). I have tried to duplicate the algorithm from https://forums.ni.com/t5/LabVIEW/Computing-CRC/m-p/825331/highlight/true#M375052 but substituting my data without success.

Could someone please help me convert the following code from Python, I have been stuck on this for the past several days and I need to move forward. Thank you for your help in advance:

"""Global Variables --> FOR TESTING ONLY <--"""
bitstring = '10000010'
polynomial_key = '10011'
initial_filler = '1'
value_check = '0111'


def crc_calculation(bit_string, bitstring_key, filler):
    """Calculates the CRC with the use of fillers"""
    bitstring_key = bitstring_key.lstrip('0')  # Strips all leading zeros
    bit_length = len(bit_string)  # Length of bitstring
    # Length of polynomial bistring and subtracts one, multiplied by filler
    # 0 - adds 0's to the end of the bitstring length - 1
    # 1 - adds 1's to the end of bitstring length - 1
    add_padding = (len(bitstring_key) - 1) * filler
    padded_array = list(bit_string + add_padding)  # Adds initial padding values to the end of bitstring
    while '1' in padded_array[:bit_length]:
        cur_shift = padded_array.index('1')
        for i in range(len(bitstring_key)):
            # XOR Operation => compares polynomial_bitstring to the current array
            padded_array[cur_shift + i] = str(int(bitstring_key[i] != padded_array[cur_shift + i]))
    return ''.join(padded_array)[bit_length:]

print(crc_calculation(bitstring, polynomial_key, initial_filler))

[pincpanter]

Well, if you tried, you must have come up with a vi, although not working. Why not posting what you've done, so we can point out what you did wrong?

[Andrey_Dmitriev · Accepted solution]

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@LV2019_Newb wrote:

Hello,

I am very new to programming in LabVIEW and have been tasked with writing an algorithm in LabView2019 that uses the polynomial 0x13 (x^4+x^1+1). I have tried to duplicate the algorithm from https://forums.ni.com/t5/LabVIEW/Computing-CRC/m-p/825331/highlight/true#M375052 but substituting my data without success.

Could someone please help me convert the following code from Python, I have been stuck on this for the past several days and I need to move forward. Thank you for your help in advance:

"""Global Variables --> FOR TESTING ONLY <--"""
bitstring = '10000010'
polynomial_key = '10011'
initial_filler = '1'
value_check = '0111'


def crc_calculation(bit_string, bitstring_key, filler):
    """Calculates the CRC with the use of fillers"""
    bitstring_key = bitstring_key.lstrip('0')  # Strips all leading zeros
    bit_length = len(bit_string)  # Length of bitstring
    # Length of polynomial bistring and subtracts one, multiplied by filler
    # 0 - adds 0's to the end of the bitstring length - 1
    # 1 - adds 1's to the end of bitstring length - 1
    add_padding = (len(bitstring_key) - 1) * filler
    padded_array = list(bit_string + add_padding)  # Adds initial padding values to the end of bitstring
    while '1' in padded_array[:bit_length]:
        cur_shift = padded_array.index('1')
        for i in range(len(bitstring_key)):
            # XOR Operation => compares polynomial_bitstring to the current array
            padded_array[cur_shift + i] = str(int(bitstring_key[i] != padded_array[cur_shift + i]))
    return ''.join(padded_array)[bit_length:]

print(crc_calculation(bitstring, polynomial_key, initial_filler))

---

May be you have to use the given VI "AIT - Utility - CRC - CRC.vi" from linked message something like this:

Isn't?

[LV2019_Newb]

Thank you very much for your help. I now see where I was making the mistake.