func (d *Device) transferN(endpoint uint8, data []byte, n int) error {
if m := int(C.libusb_get_max_packet_size(d.dev, C.uchar(endpoint))); n == 0 {
n = m
} else if n > m {
return errors.New("invalid packet size")
}
for len, off := len(data), 0; len > 0; {
var transferred int
if n > len {
n = len
}
if err := C.libusb_bulk_transfer(d.handle, C.uchar(endpoint), (*C.uchar)(&data[off]), C.int(n),
(*C.int)(unsafe.Pointer(&transferred)), 2500); err != C.LIBUSB_SUCCESS {
return &libusbError{err}
}
len -= transferred
off += transferred
}
return nil
}
// Convenience function to retrieve the MaxPacketSize value for a particular endpoint in the active device configuration.
func (d *Device) GetMaxPacketSize(endpoint byte) int {
return int(C.libusb_get_max_packet_size(d.me(), C.uchar(endpoint)))
}
func (dev *Device) GetMaxPacketSize(endpoint int) (int, *UsbError) {
sz, err := decodeUsbError(C.libusb_get_max_packet_size(dev.device, C.uchar(endpoint)))
return sz, err
}
