Controller input on classic 16 bit computers is fairly limited. JoeyLib abstracts to a common API as best as it can. More details will be coming as the Amiga and ST backends are completed.
Returns a value between -128 and 127 with 0 representing the centered position. Axis 0 is the horizontal (X) axis and axis 1 is the vertical (Y) axis. On systems with analog controllers, the result will vary depending on how far the axis has moved off center. You will need to take into account a small "dead zone" for sticks that do not have a precise center position. On platforms with more than one analog stick, JoeyLib uses the left-hand stick. If the platform supports more than one controller, all connected controllers at application startup will be used.
Most platforms support two or more buttons. JoeyLib limits button input to two. How to handle platforms with a single button has yet to be decided.