[PHP] 16bit hashing algo

[SplitIce]

reverse CRC16 with some minor changes, extremely fast for a user code hashing algorithm.

/* reverse CRC16 */
    function rCRC16($d)
    {
        if(empty($d)) return 0;
        $crc = 0xFFFF;
        for ($i = (strlen($d)-1); $i ; --$i)
        {
            $x = (($crc >> 8) ^ ord($d[$i])) & 0xFF;
            $x ^= $x >> 4;
            $crc = (($crc << 8) ^ ($x << 12) ^ ($x << 5) ^ $x) & 0xFFFF;
        }
        return $crc;
    } 

Fits inside an unsigned small integer in mysql (2 bytes / 16 bits)

SplitIce Reviewed by SplitIce on 5th Dec 2010. [PHP] 16bit hashing algo reverse CRC16 with some minor changes, extremely fast for a user code hashing algorithm. /* reverse CRC16 */ function rCRC16($d) { if(empty($d)) return 0; $crc = 0xFFFF; for ($i = (strlen($d)-1); $i ; --$i) { Rating: 5