Flags are generated only at A1 match start if MODE is 0. If MODE is set to 1 flags are also generated at the cycle boundary.
When the FLAG is set, interrupt can be triggered. But how to distinguish FLAG is set at A1 match or cycle boundary?
there is no way to distinguish between those, unless you read CNT value, but even this could not give you right decision in same cases.
Thanks Petr for your answer, I find a way.