How to classify following CRC4 implementation? - crc

Question

I figured out the following CRC4 C code with polynomial 0x13 will work for me. But regarding crcany resp. CRC catalogue how to classify it?
uint8_t const crcTable[] = {
0x0, 0x3, 0x6, 0x5, 0xC, 0xF, 0xA, 0x9, 0xB, 0x8, 0xD, 0xE, 0x7, 0x4, 0x1, 0x2,
0x5, 0x6, 0x3, 0x0, 0x9, 0xA, 0xF, 0xC, 0xE, 0xD, 0x8, 0xB, 0x2, 0x1, 0x4, 0x7,
0xA, 0x9, 0xC, 0xF, 0x6, 0x5, 0x0, 0x3, 0x1, 0x2, 0x7, 0x4, 0xD, 0xE, 0xB, 0x8,
0xF, 0xC, 0x9, 0xA, 0x3, 0x0, 0x5, 0x6, 0x4, 0x7, 0x2, 0x1, 0x8, 0xB, 0xE, 0xD,
0x7, 0x4, 0x1, 0x2, 0xB, 0x8, 0xD, 0xE, 0xC, 0xF, 0xA, 0x9, 0x0, 0x3, 0x6, 0x5,
0x2, 0x1, 0x4, 0x7, 0xE, 0xD, 0x8, 0xB, 0x9, 0xA, 0xF, 0xC, 0x5, 0x6, 0x3, 0x0,
0xD, 0xE, 0xB, 0x8, 0x1, 0x2, 0x7, 0x4, 0x6, 0x5, 0x0, 0x3, 0xA, 0x9, 0xC, 0xF,
0x8, 0xB, 0xE, 0xD, 0x4, 0x7, 0x2, 0x1, 0x3, 0x0, 0x5, 0x6, 0xF, 0xC, 0x9, 0xA,
0xE, 0xD, 0x8, 0xB, 0x2, 0x1, 0x4, 0x7, 0x5, 0x6, 0x3, 0x0, 0x9, 0xA, 0xF, 0xC,
0xB, 0x8, 0xD, 0xE, 0x7, 0x4, 0x1, 0x2, 0x0, 0x3, 0x6, 0x5, 0xC, 0xF, 0xA, 0x9,
0x4, 0x7, 0x2, 0x1, 0x8, 0xB, 0xE, 0xD, 0xF, 0xC, 0x9, 0xA, 0x3, 0x0, 0x5, 0x6,
0x1, 0x2, 0x7, 0x4, 0xD, 0xE, 0xB, 0x8, 0xA, 0x9, 0xC, 0xF, 0x6, 0x5, 0x0, 0x3,
0x9, 0xA, 0xF, 0xC, 0x5, 0x6, 0x3, 0x0, 0x2, 0x1, 0x4, 0x7, 0xE, 0xD, 0x8, 0xB,
0xC, 0xF, 0xA, 0x9, 0x0, 0x3, 0x6, 0x5, 0x7, 0x4, 0x1, 0x2, 0xB, 0x8, 0xD, 0xE,
0x3, 0x0, 0x5, 0x6, 0xF, 0xC, 0x9, 0xA, 0x8, 0xB, 0xE, 0xD, 0x4, 0x7, 0x2, 0x1,
0x6, 0x5, 0x0, 0x3, 0xA, 0x9, 0xC, 0xF, 0xD, 0xE, 0xB, 0x8, 0x1, 0x2, 0x7, 0x4
};
uint8_t crc4(uint8_t const message[], int nBytes)
{
uint8_t data;
uint8_t remainder = 0;
for (int byte = 0; byte < nBytes; ++byte)
{
data = message[byte] ^ remainder;
remainder = (crcTable[data] ^ (remainder << 8)) << 4;
}
return (remainder >> 4);
}

Answer 1

That would be:
width=4 poly=3 init=0 refin=false refout=false xorout=0 check=0xe residue=0 name="CRC-4/USER3095936"
or abbreviated:
w=4 p=3 r=f c=14 n=CRC-4/USER3095936
By the way, the code has some odd things. The ^ (remainder << 8) does nothing at all, since that's always zero. You can just get rid of that. Second, you can avoid shifting in the loop by shifting all the table entries up four bits.