Function libopencm3_sys::usbd_ep_read_packet

pub unsafe extern "C" fn usbd_ep_read_packet(
    usbd_dev: *mut usbd_device, 
    addr: u8, 
    buf: *mut c_void, 
    len: u16
) -> u16

Read a packet @param addr EP address @param len # of bytes @return Actual # of bytes read