detect if a string contains 60% or more arabic

detect_arabic.php

function uniord($u) {
    // I just copied this function fron the php.net comments, but it works fine!
    $k = mb_convert_encoding($u, 'UCS-2LE', 'UTF-8');
    $k1 = ord(substr($k, 0, 1));
    $k2 = ord(substr($k, 1, 1));
    return $k2 * 256 + $k1;
}
//returns true or false if string contains 60% or more arabic characters
function is_arabic($str){
        if(mb_detect_encoding($str) !== 'UTF-8') {
                $str = mb_convert_encoding($str,mb_detect_encoding($str),'UTF-8');
        }
        /*
        $str = str_split($str); <- this function is not mb safe, it splits by bytes, not characters. we cannot use it
        $str = preg_split('//u',$str); <- this function woulrd probably work fine but there was a bug reported in some php version so it pslits by bytes and not chars as well
        */
        preg_match_all('/.|\n/u', $str, $matches);
        $chars = $matches[0];
        $arabic_count = 0;
        $latin_count = 0;
        $total_count = 0;
        foreach($chars as $char){
                //$pos = ord($char); we cant use that, its not binary safe 
                $pos = uniord($char);
                #echo $char ." --> ".$pos.PHP_EOL;
                if($pos >= 1536 && $pos <= 1791){
                        $arabic_count++;
                }elseif($pos > 123 && $pos < 123){
                        $latin_count++;
                }
                $total_count++;
        }
        if(($arabic_count/$total_count) > 0.6) {
                // 60% arabic chars, its probably arabic
                return true;
        }
        return false;
}