pocketmine\utils\Binary::writeLFloat PHP Method

    public static function writeLFloat($value)
    {
        return ENDIANNESS === self::BIG_ENDIAN ? strrev(pack("f", $value)) : pack("f", $value);
    }

 public function putFloat($v)
 {
     $this->buffer .= $this->endianness === self::BIG_ENDIAN ? Binary::writeFloat($v) : Binary::writeLFloat($v);
 }