How to calculate CRC16 CCITT in PHP HEX?

Question

I\'m trying to use a PHP CRC16 CCITT function to calculate the checksum.

A device sends me a PACKET with Checksum included:

10 00 00 00 00 00

Answer 1

I found out from the Deplhi function how it works. It gets an byte Array, instead of Hex string for doing the job. Here is the code:

// $commands = [0x35, 0x02, 0x02, 0x00, 0x10, 0x03];       // => 0x5ba3
$commands = [0x44, 0x02, 0x02, 0x01, 0x10, 0x03];       // => 0x55c0
var_dump(dechex(getChecksum($commands)));

function getChecksum($byteArray) {
    $polynom = 0x8408;
    $in_crc = 0x0000;
    for ($i = 0; $i < sizeof($byteArray); $i++) {
        for ($n = 0; $n < 8; $n++) {
            if((($byteArray[$i] & 0x0001) ^ $in_crc) & 0x0001) 
                $in_crc = ($in_crc >> 1) ^ $polynom;
            else 
                $in_crc = $in_crc >> 1;
            $byteArray[$i] = $byteArray[$i] >> 1;
        }
        $result = $in_crc;
    }
    return $result;
}

The solution can be proved on this Online CRC Calculator. The Algorithm used is CRC-16/KERMIT.