Stew's script to work around his broken y axis

fix-broken-cougar-y-axis.py

from evdev import ecodes, uinput, AbsInfo, InputDevice

# This script works around a broken y axis for my Thrustmaster Cougar throttle.
# The y axis reads off center, this works around it by scaling the reported value around an offset
# It's not perfect, but it makes the joystick usable at least.
# The script works by grabbing exclusive access to the real device and proxying its events
# to a new virtual device, applying value fixes to the appropriate events

# The ID of my broken 20 year old Thrustmaster Cougar
input_device = InputDevice('/dev/input/by-id/usb-Thrustmaster_Thrustmaster_HOTAS_Cougar-event-joystick')

# Take exclusive access of the input
input_device.grab()

# TODO: Copy vendor info and give a better name
output_device = uinput.UInput.from_device(input_device)

# Account for the y axis offset which reads ~47830 when centered
def fix_dodgy_y_axis(value: int) -> int:
    if not (0 <= value <= 65536):
        raise ValueError("Input must be between 0 and 65536")
    return int(value / 47830 * 32768) if value <= 47830 else int(32768 + (value - 47831) / (65536 - 47831) * 32768)

# Proxy every event
for event in input_device.read_loop():
    # Handle ABS events produced by joystick axes
    if event.type == ecodes.EV_ABS:
        # Fix my dodgy y axis
        if event.code == ecodes.ABS_Y:
            event.value = fix_dodgy_y_axis(event.value)

    output_device.write_event(event)
    output_device.syn()