In crc16 function ,can we add other polynomials?

[Tengfei Tu]

Hi, I find crc16 algorithms has many other polynomials.
In helper.py, crc16 function is:
"
def crc16(string, value=0):
"""
CRC-16 poly: p(x) = x16 + x15 + x**2 + 1
"""
crc16_table = []
for byte in range(256):
crc = 0

    for bit in range(8):
        if (byte ^ crc) & 1:
            crc = (crc >> 1) ^ 0xa001  # polly
        else:
            crc >>= 1

        byte >>= 1

    crc16_table.append(crc)

for ch in string:
    value = crc16_table[ord(ch) ^ (value & 0xff)] ^ (value >> 8)

return value

"

and I am not sure the funtion can be writen like this:
"
def crc16(string, value=0xa001):
"""
CRC-16 poly: p(x) = x16 + x15 + x**2 + 1
@:param value:
CRC-16 model
P_16 0xa001
P_CCITT 0x1021
P-DNP 0xa6bc
p_KERMIT 0x8408
P_SICK 0x8005
"""
crc16_table = []
for byte in range(256):
crc = 0

    for bit in range(8):
        if (byte ^ crc) & 1:
            crc = (crc >> 1) ^ value  # poly
        else:
            crc >>= 1

        byte >>= 1

    crc16_table.append(crc)

for ch in string:
    value = crc16_table[ord(ch) ^ (value & 0xff)] ^ (value >> 8)

return value

"

[Ryan]

Hi there,

I'm not sure I follow with all the in-line text. Can you re-format your question with proper markdown, or submit a PR?

Thanks!

[Tengfei Tu]

ok， I am sorry. I do not have a clear descrption of the problem. Meanwhile, I have another question.