This function will compute the CRC of a hexstring

mbms_crc_example.c

// Using code from http://www.sunshine2k.de/articles/coding/crc/understanding_crc.html#ch5
// Using MBMS header bits from the pcap in wireshark bug#14875
// Expected output is 52 (0x34), which is the correct answer

#include <stdio.h>

int main(){
    const int generator = 0x2f;
    int crc = 0; /* start with 0 so first byte can be 'xored' in */
    // 0x10043b000000000000 aligned to 6 bits (from pcap)
    // 3 nibbles = 4x 6 bits
    int bytes[12] = {4,0,16,59, 0,0,0,0, 0,0,0,0};

    for(int i=0; i < 12; i++)
    {
      int currByte = bytes[i];
        crc ^= currByte; /* XOR-in the next input byte */

        for (int i = 0; i < 6; i++)
        {
            if ((crc & 0x20) != 0)
            {
                crc = ((crc << 1) ^ generator) & 0x3f;
            }
            else
            {
                crc <<= 1;
            }
        }
    }

    printf("%i", crc);
}