USBMS_BUT
if (c & USBMS_BUT(1)) { /* left button is pressed */
if (c & USBMS_BUT(2)) { /* right button is pressed */
if (c & USBMS_BUT(3)) { /* middle button is pressed */
if (c & USBMS_BUT(i)) {
hwbit = USBMS_BUT(nbutt) >> (EVENT_BUT(nbutt) -