diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c index 8a37204..59625a4 100644 --- a/libevdev/libevdev.c +++ b/libevdev/libevdev.c @@ -41,12 +41,38 @@ static int sync_mt_state(struct libevdev *dev, int create_events); static int init_event_queue(struct libevdev *dev) { - /* FIXME: count the number of axes, keys, etc. to get a better idea at how many events per - EV_SYN we could possibly get. Then multiply that by the actual buffer size we care about */ + const int MIN_QUEUE_SIZE = 256; + int nevents = 1; /* terminating SYN_REPORT */ + int nslots; + unsigned int type, code; - const int QUEUE_SIZE = 256; + /* count the number of axes, keys, etc. to get a better idea at how + many events per EV_SYN we could possibly get. That's the max we + may get during SYN_DROPPED too. Use double that, just so we have + room for events while syncing an event. + */ + for (type = EV_KEY; type < EV_MAX; type++) { + int max = libevdev_event_type_get_max(type); + for (code = 0; max > 0 && code < (unsigned int) max; code++) { + if (libevdev_has_event_code(dev, type, code)) + nevents++; + } + } - return queue_alloc(dev, QUEUE_SIZE); + nslots = libevdev_get_num_slots(dev); + if (nslots > 1) { + int num_mt_axes = 0; + + for (code = ABS_MT_SLOT; code < ABS_MAX; code++) { + if (libevdev_has_event_code(dev, EV_ABS, code)) + num_mt_axes++; + } + + /* We already counted the first slot in the initial count */ + nevents += num_mt_axes * (nslots - 1); + } + + return queue_alloc(dev, min(MIN_QUEUE_SIZE, nevents * 2)); } static void