Fix KeyAddrEventQueue::shouldAbort() (qukeys getting stuck)
#1321
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This test reproduces a bug where key events can get dropped by plugins that use KeyAddrEventQueue, causing keys to be non-responsive or getting stuck on. Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>
The compiler promotes our signed 8-bit integer to a 16-bit integer, at least on some processors. This causes the wrong result for `shouldAbort()` when the new event's id is -128, and the one at the head of the queue is 127. Fixes keyboardio#1320 Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>
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This fixes a problem that was causing key events to get dropped in some cases when the event id rolled over from positive to negative values while a plugin had events queued spanning both sides of the overflow. This would generally result in event
127getting dropped. If the dropped event was a keyswitch toggling on, the key would be unresponsive. If it was a key release, the key would get "stuck on".The problem was that the 8-bit integer
KeyEventIdvalues were getting promoted to 16-bit integers when computing the difference between the event being flushed from the queue and the event at the head of the queue. The resulting 16-bit value (-128 - 127) would be negative, whereas its 8-bit counterpart would be positive, resulting in a false positive return value fromshouldAbort(). The fix is to convert the difference back to an 8-bit integer before doing the comparison with zero.I've included a testcase that fails without the fix.