struct input_mt — state of tracked contacts
struct input_mt {
int trkid;
int num_slots;
int slot;
unsigned int flags;
unsigned int frame;
int * red;
struct input_mt_slot slots[];
}; stores MT tracking ID for the next contact
number of MT slots the device uses
MT slot currently being transmitted
input_mt operation flags
increases every time input_mt_sync_frame is called
reduced cost matrix for in-kernel tracking
array of slots holding current values of tracked contacts