ParagonIE_Sodium_Core_Util::load64_le

    public static function load64_le($string)
    {
        /* Type checks: */
        if (!is_string($string)) {
            throw new TypeError('Argument 1 must be a string, ' . gettype($string) . ' given.');
        }

        /* Input validation: */
        if (self::strlen($string) < 4) {
            throw new RangeException(
                'String must be 4 bytes or more; ' . self::strlen($string) . ' given.'
            );
        }
        if (PHP_VERSION_ID >= 50603 && PHP_INT_SIZE === 8) {
            /** @var array<int, int> $unpacked */
            $unpacked = unpack('P', $string);
            return (int) $unpacked[1];
        }

        /** @var int $result */
        $result  = (self::chrToInt($string[0]) & 0xff);
        $result |= (self::chrToInt($string[1]) & 0xff) <<  8;
        $result |= (self::chrToInt($string[2]) & 0xff) << 16;
        $result |= (self::chrToInt($string[3]) & 0xff) << 24;
        $result |= (self::chrToInt($string[4]) & 0xff) << 32;
        $result |= (self::chrToInt($string[5]) & 0xff) << 40;
        $result |= (self::chrToInt($string[6]) & 0xff) << 48;
        $result |= (self::chrToInt($string[7]) & 0xff) << 56;
        return (int) $result;
    }