WTF/gamecontrollerdb.txt and C_GamePad.AddSDLMapping do not work

[seblindfors]

In an attempt to remedy #482 I have played around with SDL mappings, using both external tools and writing a small in-game tool for this purpose. However, it seems that this was a waste of time, because neither loading mapping profiles from the db file nor the in-game API works. Whatever goes in there is just ignored.

• DualSense Edge Wireless Controller, connected by bluetooth
• Tested on all game clients, doesn't work on any of them

SDL = {};
---------------------------------------------------------------
-- SDL Mappings
---------------------------------------------------------------
---@enum SDL.HardwareBus
SDL.HardwareBus = {
	USB         = 0x03;
	Bluetooth   = 0x05;
	Virtual     = 0xFF;
};

---@class SDL.GUID
---@field bus number
---@field vendorID number|string
---@field productID number|string
---@field revision number|string

---@alias SDL.ButtonMap table<string, string>

---@class SDL.Mapping
---@field name string
---@field guid SDL.GUID
---@field mapping string
---@field platform Enum.ClientPlatformType

function SDL.BigLittleEndian(hex)
	hex = ('%08x'):format(type(hex) == 'string' and tonumber(hex, 16) or hex);
	local littleEndian = '';
	for i = #hex, 1, -2 do
		littleEndian = littleEndian .. hex:sub(i-1, i)
	end
	print(hex, littleEndian);
	return littleEndian;
end

---@param guid SDL.GUID
---@return string guid <bus><vendorID><productID><revision> 
function SDL.MakeSDLGUID(guid)
	return table.concat({
		SDL.BigLittleEndian(guid.bus or SDL.HardwareBus.USB),
		SDL.BigLittleEndian(guid.vendorID),
		SDL.BigLittleEndian(guid.productID),
		SDL.BigLittleEndian(guid.revision or 0),
	}, ''):lower();
end

function SDL.MakeConfig(mapping)
	local config = {};
	for id, value in pairs(mapping) do

		config[#config + 1] = ('%s:%s'):format(id, value);
	end
	return table.concat(config, ',');
end

---@param name string
---@param guid SDL.GUID
---@param mapping SDL.ButtonMap
---@return string
function SDL.MakeSDLMapping(name, guid, mapping)
	return table.concat({
		SDL.MakeSDLGUID(guid),
		name,
		SDL.MakeConfig(mapping)
	}, ',') .. ',';
end

---@param name string
---@param guid SDL.GUID
---@param mapping SDL.ButtonMap
---@param platform Enum.ClientPlatformType
---@return boolean success
function SDL.AddSDLMapping(name, guid, mapping, platform)
	local entry = SDL.MakeSDLMapping(name, guid, mapping);
	print(entry);
	return C_GamePad.AddSDLMapping(platform or Enum.ClientPlatformType.Windows, entry);
end

-- Generates:
-- 050000004c050000f20d000000010000,DualSense Edge Wireless,paddle2:b15,b:b1,leftstick:b7,dpleft:h0.8,leftx:a0,leftshoulder:b9,lefty:a1,a:b0,righttrigger:a5,touchpad:b11,rightx:a2,rightshoulder:b10,lefttrigger:a4,righty:a3,start:b6,y:b3,x:b2,dpup:h0.1,paddle4:b13,dpright:h0.2,paddle1:b16,rightstick:b8,paddle3:b14,dpdown:h0.4,guide:b5,misc1:b12,back:b4,
SDL.AddDS5Edge = function()
	return SDL.AddSDLMapping('DualSense Edge Wireless', {
		bus       = SDL.HardwareBus.Bluetooth,
		vendorID  = 0x054C,
		productID = 0x0DF2,
		revision  = 0x100,
	}, {
		a = 'b0',
		b = 'b1',
		x = 'b2',
		y = 'b3',
		back = 'b4',
		guide = 'b5',
		start = 'b6',
		leftstick = 'b7',
		rightstick = 'b8',
		leftshoulder = 'b9',
		rightshoulder = 'b10',
		touchpad = 'b11',
		misc1 = 'b12',
		paddle4 = 'b13',
		paddle3 = 'b14',
		paddle2 = 'b15',
		paddle1 = 'b16',
		dpdown = 'h0.4',
		dpleft = 'h0.8',
		dpright = 'h0.2',
		dpup = 'h0.1',
		leftx = 'a0',
		lefty = 'a1',
		rightx = 'a2',
		righty = 'a3',
		lefttrigger = 'a4',
		righttrigger = 'a5',
	});
end

Invoking SDL.AddDS5Edge() returns true as if the API call was successful but nothing changes. Using GamePadListDevices doesn't show any change.

The GUID used for the controller is based on the original SDL_gamepad_db.h although I've also tried with the GUID identified by SDL2 Gamepad Tool which uses the USB bus on Windows 11 and doesn't have the device revision.

I replicated the config based on SDL_CreateMappingForHIDAPIGamepad for this test case.