transport.py 文件源码

def open(self, usb_bus, dev_adr):
        self.usb_dev = None
        self.usb_out = None
        self.usb_inp = None

        for dev in self.context.getDeviceList(skip_on_error=True):
            if ((dev.getBusNumber() == usb_bus and
                 dev.getDeviceAddress() == dev_adr)):
                break
        else:
            log.error("no device {0} on bus {1}".format(dev_adr, usb_bus))
            raise IOError(errno.ENODEV, os.strerror(errno.ENODEV))

        try:
            first_setting = dev.iterSettings().next()
        except StopIteration:
            log.error("no usb configuration settings, please replug device")
            raise IOError(errno.ENODEV, os.strerror(errno.ENODEV))

        def transfer_type(x):
            return x & libusb.TRANSFER_TYPE_MASK

        def endpoint_dir(x):
            return x & libusb.ENDPOINT_DIR_MASK

        for endpoint in first_setting.iterEndpoints():
            ep_addr = endpoint.getAddress()
            ep_attr = endpoint.getAttributes()
            if transfer_type(ep_attr) == libusb.TRANSFER_TYPE_BULK:
                if endpoint_dir(ep_addr) == libusb.ENDPOINT_IN:
                    if not self.usb_inp:
                        self.usb_inp = endpoint
                if endpoint_dir(ep_addr) == libusb.ENDPOINT_OUT:
                    if not self.usb_out:
                        self.usb_out = endpoint

        if not (self.usb_inp and self.usb_out):
            log.error("no bulk endpoints for read and write")
            raise IOError(errno.ENODEV, os.strerror(errno.ENODEV))

        try:
            # workaround the PN533's buggy USB implementation
            self._manufacturer_name = dev.getManufacturer()
            self._product_name = dev.getProduct()
        except libusb.USBErrorIO:
            self._manufacturer_name = None
            self._product_name = None

        try:
            self.usb_dev = dev.open()
            self.usb_dev.claimInterface(0)
        except libusb.USBErrorAccess:
            raise IOError(errno.EACCES, os.strerror(errno.EACCES))
        except libusb.USBErrorBusy:
            raise IOError(errno.EBUSY, os.strerror(errno.EBUSY))
        except libusb.USBErrorNoDevice:
            raise IOError(errno.ENODEV, os.strerror(errno.ENODEV))