HID_CONTROL_FIFO_SIZE
(HID_CONTROL_FIFO_SIZE - 1);
usbhid->ctrltail = (usbhid->ctrltail + 1) & (HID_CONTROL_FIFO_SIZE - 1);
if ((head = (usbhid->ctrlhead + 1) & (HID_CONTROL_FIFO_SIZE - 1)) == usbhid->ctrltail) {
struct hid_control_fifo ctrl[HID_CONTROL_FIFO_SIZE]; /* Control fifo */
struct hid_output_fifo out[HID_CONTROL_FIFO_SIZE]; /* Output pipe fifo */