convert code from javascript function to php

any one can help me to convert this function to generate hash Code to php i try to convert but not working

function hashCode(str) {
    let hash = 0;

    for (let i = 0; i < str.length; i++) {
        let char = str.charCodeAt(i);
        hash = ((hash << 5) - hash) + char;
        hash = hash & hash; // Convert to 32bit integer
    }

    hash = hash.toString(16);
    if (hash[0] == '-')
    {
        hash = 'n' + hash.substr(1);
    }

    return hash;
}

i try this but not wroking

function hashCode($str) {
    $str = (string)$str;
    $hash = 0;
    $len = strlen($str);
    if ($len == 0 )
        return $hash;

    for ($i = 0; $i < $len; $i++) {
        $h = $hash << 5;
        $h -= $hash;
        $h += ord($str[$i]);
        $hash = $h;
        $hash &= 0xFFFFFFFF;
    }
    return $hash;
};