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Count the number of events needed for a full sync

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Make sure we have a queue that is at least large enough to do a full sync
after a SYN_DROPPED, plus store a few extra events in case some came in after
the sync.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
This commit is contained in:
Peter Hutterer 2014-01-17 09:24:20 +10:00
parent 4eeda3bc47
commit 77bf0fe228
1 changed files with 30 additions and 4 deletions
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34
libevdev/libevdev.c
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@ -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