TrueBV\Punycode::decodePart PHP Method

    protected function decodePart($input)
    {
        $n = static::INITIAL_N;
        $i = 0;
        $bias = static::INITIAL_BIAS;
        $output = '';
        $pos = strrpos($input, static::DELIMITER);
        if ($pos !== false) {
            $output = substr($input, 0, $pos++);
        } else {
            $pos = 0;
        }
        $outputLength = strlen($output);
        $inputLength = strlen($input);
        while ($pos < $inputLength) {
            $oldi = $i;
            $w = 1;
            for ($k = static::BASE;; $k += static::BASE) {
                $digit = static::$decodeTable[$input[$pos++]];
                $i = $i + $digit * $w;
                $t = $this->calculateThreshold($k, $bias);
                if ($digit < $t) {
                    break;
                }
                $w = $w * (static::BASE - $t);
            }
            $bias = $this->adapt($i - $oldi, ++$outputLength, $oldi === 0);
            $n = $n + (int) ($i / $outputLength);
            $i = $i % $outputLength;
            $output = mb_substr($output, 0, $i, $this->encoding) . $this->codePointToChar($n) . mb_substr($output, $i, $outputLength - 1, $this->encoding);
            $i++;
        }
        return $output;
    }