If your lucky to have
switches with two outputs and one input will the best way to
avoid bouncing be a SR-latch.
If your working on/off
switches and buttons will some kind of RC-filtering be a
solution - eventually together with a buffer with some
hysteresis (smith-trigger input)
Finally can bouncing be
removed with a relative simple filter - involving a shift
register with n-bits, a SR-latch and some logic.
Its your task to
Implement this as a VHDL code
(Please note that this circuit not
the "ideal" solution and is bound to be modified)