2. Joystick drivers

Unfortunately, none of the input provided by any joystick driver has information about the kind of features it belongs to. Drivers simply provide a long list of values. Generally, these are bools or floats, but some interfaces use enums, like the directions on a d-pad.

To connect this information to the features of a controller profile, it is split into elements that better translate to controller features. These elements are called driver primitives.

2.1. Types of driver primitives

Buttons

Consider a bool reported by the driver. This probably belongs to something that can be pressed, so it's called a button. A bool can't belong to multiple features, so it is a driver primitive.

Hat directions

Some drivers use enums or bit flags to report hat presses. In Kodi, hats are treated like four separate buttons for simplicity. Hat enums can belong to four features, so they contain four driver primitives, one for each direction.

Semiaxis directions

A float is a little trickier. The immediate assumption is an axis of an analog stick or accelerometer. However, in DirectInput, triggers are combined into a single float. Therefore, a float can map to two features, so each half of the axis (called a semiaxis) is a driver primitive.

This has interesting implications. An analog stick has two axes, which is four driver primitives. Each semiaxis can map to a different feature, so the analog stick is able to emulate the four buttons of a d-pad, or the N64's C buttons.