If someone would like to try ... I can test windows build only with wine on Linux, it seems to work there. The "usual" -entermice prefixed distribution URL is used
The "only" problem is mapping to controller events. Ie modern controllers have even about a dozen of button ID, axes, even "hats". For software, they don't know what are those buttons, axes, etc for real, only "button 1" or "axis 3", and these IDs means totally different things on different pads/joysticks, or even on different operating systems (maybe version dependent too ...) and drivers! Thus, now only there is a single hard wired config which seems to work here on Linux and X-Box controller, but that's all. It can be tricky to try to find, which controller element does "UP" or "FIRE"
In the future, I would need some calibration possibility, so user can set it in an interactive way, then Xep128 stores that (also with the "GUID" of the controller - that's an identifier for a given controller -, so it will now that different controller needs another calibration ...) and can re-use it later.
Currently, only one gamepad/joystick is recognized with the fixed mapping I've talked about. Now, the events are distributed for both of the external joysticks on the same time, and still, numeric keypad can override, and can be used as an "external joystick". I'm also thinking on the possibility to have option for using game controller/joystick to emulate the internal joystick, but as we know, it's a different issue, as that's part of the "main keyboard matrix".
A hint: in IS-BASIC you can enter this command ":XEP showkeys" (also on the console/monitor window, without the :XEP part then, only "showkeys"). It causes Xep128 will give visual feedback (via OSD) about every pressed key and joystick emulation event. Now button #0 and axes #0/#1 are used only. Issuing the mentioned command again caused to turn this "debug mode" off.
In theory, Xep128 supports hot-plug (add/remove) the USB controller (try plug pad in/out while Xep128 is running), and it will show via OSD about the event. Anyway, not so useful, as only one config is used with the joy #0 on the system only.
Interesting, that SDL has some support for the "haptic" stuffs (I have no idea about the meaning of this word to be honest, SDL names that way ...), ie to "rumble" the controller. I have no idea if it's useful for anything for an Enterprise emulator