The scripted-input tool this project uses for reverse engineering created its
pad through /dev/uinput. Input devices are NOT namespaced by the kernel, so a
uinput device created inside a container registers with the HOST's input stack:
every trigger hold and button press is delivered to whatever on the host reads
gamepads, not just to the emulator. That was noticed the hard way, and it made
every runtime experiment -- booting, menu navigation, unit harvesting, flight
measurement -- unusable from inside the box.
This driver takes the kernel out of the loop. Pad state lives in an ordinary
text file only the container can see; GetState re-reads it when it changes.
Nothing is registered with the host and no X server is involved. A bonus for RE:
analogue values are exact rather than whatever a virtual stick quantises to.
press=A,START buttons by name, comma separated
buttons=0x1010 or the raw XINPUT mask
lt=0 rt=255 triggers, 0..255
lx=0 ly=0 thumbs, -32768..32767
Absent keys are neutral, so `press=A` alone is a valid file, and a missing or
empty file means no input -- the safe default if it is deleted mid-run.
Selected with --hid=file, path from --pad_file (default /tmp/xenia_pad.txt).
Deliberately NOT part of "any": this pad has to be asked for. Header-only, so it
adds no build target and no cost to anyone not using it.
