Since bouncing was in the range of some ms, there must be inserted a delay of about 2..200ms.
So it is suggested to insert the debouncing routine inside the timer interrupt.

I use a similiar solution already over years:

http://www.8052.com/forum/read.phtml?id=57958

I have added a 4th byte which contain the transition state.
Since most times the changing from the released to the pressed state should be used to do something.


Peter