func (h *DeviceHandle) GetStringDescriptor(index byte, langid uint16) (string, *UsbError) {
buf := make([]uint16, 128)
rlen, err := decodeUsbError(C.libusb_get_string_descriptor(h.handle, C.uint8_t(index), C.uint16_t(langid), (*C.uchar)(unsafe.Pointer(&buf[0])), 256))
if err != nil {
return "", err
}
return string(utf16.Decode(buf[1 : rlen/2])), nil
}
func (h *DeviceHandle) GetLangIds() ([]uint16, *UsbError) {
var buf [256]C.uchar
u16buf := (*[128]C.uint16_t)(unsafe.Pointer(&buf[0]))
rlen, err := decodeUsbError(C.libusb_get_string_descriptor(h.handle, 0, 0, &buf[0], 256))
if err != nil {
return nil, err
}
// I'm explicitly ignoring the first two bytes, which are length and descriptor type, respectively.
ret := make([]uint16, rlen/2-1)
for i := 1; i < rlen/2; i++ {
ret[i-1] = uint16(u16buf[i])
}
return ret, nil
}
func getStringDescriptor(dev *C.libusb_device_handle, id C.uint8_t) (string, error) {
var buf [128]C.char
const langId = 0
err := C.libusb_get_string_descriptor(dev, id, C.uint16_t(langId), (*C.uchar)(unsafe.Pointer(&buf[0])), C.int(len(buf)))
if err < 0 {
return "", usbError(err)
}
if err < 2 {
return "", errors.New("not enough data for USB string descriptor")
}
l := C.int(buf[0])
if l > err {
return "", errors.New("USB string descriptor is too short")
}
b := buf[2:l]
uni16 := make([]uint16, len(b)/2)
for i := range uni16 {
uni16[i] = uint16(b[i*2]) | uint16(b[i*2+1])<<8
}
return string(utf16.Decode(uni16)), nil
}