libusb 初探3-usb device descriptor

完整說明請見 usb device descriptor，底下僅列出資料結構:

Data Fields

uint8_t bLength
Size of this descriptor (in bytes).
uint8_t bDescriptorType
Descriptor type.
uint16_t bcdUSB
USB specification release number in binary-coded decimal.
uint8_t bDeviceClass
USB-IF class code for the device.
uint8_t bDeviceSubClass
USB-IF subclass code for the device, qualified by the bDeviceClass value.
uint8_t bDeviceProtocol
USB-IF protocol code for the device, qualified by the bDeviceClass and bDeviceSubClass values.
uint8_t bMaxPacketSize0
Maximum packet size for endpoint 0.
uint16_t idVendor
USB-IF vendor ID.
uint16_t idProduct
USB-IF product ID.
uint16_t bcdDevice
Device release number in binary-coded decimal.
uint8_t iManufacturer
Index of string descriptor describing manufacturer.
uint8_t iProduct
Index of string descriptor describing product.
uint8_t iSerialNumber
Index of string descriptor containing device serial number.
uint8_t bNumConfigurations
Number of possible configurations.