usb_frcount_t
usb_frcount_t frames; /* maximum number of USB frames */
struct usb_page_cache *usbd_xfer_get_frame(struct usb_xfer *, usb_frcount_t);
void usbd_xfer_set_frames(struct usb_xfer *xfer, usb_frcount_t n);
void usbd_xfer_set_frame_data(struct usb_xfer *xfer, usb_frcount_t frindex,
void usbd_xfer_set_frame_len(struct usb_xfer *xfer, usb_frcount_t frindex,
usbd_xfer_set_frames(struct usb_xfer* xfer, usb_frcount_t n)
usb_frcount_t frindex, void* ptr, usb_frlength_t len)
usb_frcount_t frindex, usb_frlength_t len)
usbd_xfer_get_frame(struct usb_xfer* xfer, usb_frcount_t frindex)