Workaround to remap the Donut Dodo controller buttons to Retropie's Joypad definition.

donutdodo_controller_mapping.py

#! /usr/bin/env python3

# Remaps the Donut Dodo Controller buttons to the values of Retropie's Joypad
# definition. cf. https://retropie.org.uk/forum/topic/34334/

# Usage:
#
# 1. Run Donut Dodo and in the "Remap Controller" Menu select Factory Reset
# once. This will create a
# /opt/retropie/configs/ports/donutdodo/controller_mapping.dat
#
# 2. Quit the game.
#
# 3. Then run this script with a *.cfg file of choice from the folder
# /opt/retropie/configs/all/retroarch-joypads/. E.g.
#
# ./donutdodo_controller_mapping.py "Logitech Logitech RumblePad 2 USB.cfg"

# Note: Donut Dodo p1_dpad_... buttons will not be changed.

# Tested with DonutDodo v1.39

# (C) 2023 Gemba @ Github
# License: MIT

import shutil
import sys
from pathlib import Path

dd_to_rpjoypad_map = {
    # Key mapping between
    # "Donut Dodo contoller_mapping.dat": "Retropie retroarch-joypad/*.cfg"
    # Adjust right part as needed, consult your *.cfg file for possible keys
    'p1_jump_controller': 'input_a_btn',
    'p1_start_controller': 'input_start_btn',
    'p1_select_controller': 'input_select_btn',
    'p1_options_controller': 'input_enable_hotkey_btn',
    'p1_accept_controller': 'input_a_btn',
    'p1_cancel_controller': 'input_b_btn'
}

RP_JOYPAD_CFG_PATH = Path("/opt/retropie/configs/all/retroarch-joypads")
DD_CONTROLLER_MAP_FILE = Path(
    "/opt/retropie/configs/ports/donutdodo/controller_mapping.dat")


def read_rp_joypad_props(fn):
    if fn.exists():
        config = {}
        with open(fn) as props:
            for line in [l for l in props if '=' in l]:
                name, value = line.split('=', 1)
                config[name.strip()] = value.strip().replace('"', '')
        return config
    print(f"[!] File {fn} does not exist. Exiting.")
    sys.exit(1)


def replace_button_values(dd_controller, dd_key, jp_key):
    # find controller key in *.dat file
    idx = dd_controller.find(dd_key.encode('ascii'))
    # button value is next byte after this sequence
    mark = b'\x02\x00\x00\x00'
    btn_value_idx = dd_controller.find(mark, idx)+len(mark)
    if idx:
        joypad_btn = int(rp_cfg[jp_key])
        btn_disp = dd_key.split('_')[1].upper()
        print(
            f"    {btn_disp:7s}: {dd_controller[btn_value_idx]:2d} to"
            f" {joypad_btn:2d} ({jp_key})")
        new_cfg = dd_controller[:btn_value_idx] + \
            bytes([joypad_btn]) + dd_controller[btn_value_idx+1:]
    return new_cfg


if __name__ == "__main__":

    if len(sys.argv) != 2:
        print(
            "[!] Provide a RetroPie Joypad *.cfg file."
            " See this file header for details. Exiting.")
        sys.exit(1)

    rp_joypad_cfg = sys.argv[1]
    rp_joypad_file = RP_JOYPAD_CFG_PATH / rp_joypad_cfg
    rp_cfg = read_rp_joypad_props(rp_joypad_file)
    orig_dd_map_file = DD_CONTROLLER_MAP_FILE.parent / \
        f"{DD_CONTROLLER_MAP_FILE.name}.orig"

    if not orig_dd_map_file.is_file():
        shutil.move(DD_CONTROLLER_MAP_FILE, orig_dd_map_file)
        print(f"[+] Pristine mapping moved to '{orig_dd_map_file.name}'")

    with open(orig_dd_map_file, 'rb') as in_data:
        dd_cfg = in_data.read()

    print(f"[*] Donut Dodo Controller Remapping to '{rp_joypad_file.stem}':")
    for dd_controller_key, rp_joypad_key in dd_to_rpjoypad_map.items():
        dd_cfg = replace_button_values(dd_cfg, dd_controller_key, rp_joypad_key)

    with open(DD_CONTROLLER_MAP_FILE, 'wb') as out_data:
        out_data.write(dd_cfg)
    print(f"[+] Done. New mapping written to")
    print(f"    {DD_CONTROLLER_MAP_FILE}")