CRC32.c

/**
 * CRC32 Implementation Sample
 */
// https://introcs.cs.princeton.edu/java/61data/CRC32.java.html
 
unsigned int _binary___program_bin_start(unsigned char* message, unsigned int len) {
    unsigned int crc = 0xFFFFFFFF;
    
    for(int i=0;i<len;i++) {
        unsigned int temp = (crc ^ message[i]) & 0xff;
        for (int j = 0; j < 8; j++) {
            if ((temp & 1) == 1)
                temp = (temp >> 1) ^ 0xEDB88320;
            else               
                temp = (temp >> 1);
        }
        crc = (crc >> 8) ^ temp;
    }
    
    len = 5;
    return ~crc;
}