XInput and HID - architecture

[Roderick Colenbrander]

Hi Juan,

Let me reply to the start of the thread before diving into the
specifics on calibration.

In my opinion, I'm not sure what the best way would be to handle
passing of HID data to xinput. The main thing to consider as part of
this is handling of non-native xinput devices (e.g. DS4 or
SteamController) provided we want to support this. Aside from passing
up the HID data the other challenge for xinput devices is the
enumeration part, which many (older) games do through a mixture of
WMI, dinput and xinput. For this to work we need to report an actual
xinput gamepad.

My feeling would be for xinput to be quite stupid like it is on
Windows and feed it xbox controller compatible HID reports with the
same axes ranges, rumble ranges as the xbox controller. For more
custom devices you may want to support special handling e.g. button
emulation using touchpad on DS4 or maybe even on SteamController.

As you have seen the xbox controller lacks proper HID descriptors and
on Windows the drivers fake descriptors to allow DirectInput to work
as well. We would be doing something not to different. For the
DirectInput I would report the real device name and the real ranges,
similar if games use raw input (not sure if there are games which do
this).

Thanks,
Roderick




On Thu, Mar 3, 2016 at 12:39 AM, Juan Jose Gonzalez <juanj.gh at gmail.com> wrote:
> Hi,
>
> I got a bit stuck and would like to hear your opinion on the XInput HID
> backend, specifically on the mappings, i.e. the code that "accepts" a
> certain device based on its properties and then maps its buttons and axes to
> XInput buttons and axes.
>
> As long as the mappings are fixed, i.e. are not supposed to be extended or
> edited by the user, everything can be compiled into xinput1_3.dll. However,
> I would like to provide a "xinput.cpl" control panel node for xinput similar
> to "joy.cpl", where the user can not only test the XInput gamepads, but also
> manage the XInput-HID backend mappings. The first part can be accomplished
> by using xinput1_3.dll. However, in order to load and persist different
> mappings, the second part requires access to the functions that serialize
> and deserialize the mappings. It also needs some way of getting raw
> capabilities and changes in HID devices in order to be able to create new
> mappings.
>
> Here are some possible ways of solving it:
>
> Extend xinput1_3.dll with the required management functions and add a
> "wine/xinput_hid_mgmt.h" or similar header that declares those methods.
> xinput.cpl could then simply use xinput1_3.dll to perform all management
> functions. I'm not sure if this would break anything due to the additional
> exports in the dll.
> Extract the mapping load and store logic into a separate "xinputhid.dll" or
> similar. I this case both xinput1_3.dll and xinput.cpl would access this
> library to load and store mappings.
> Move the xinput core and backends into a driver and let xinput1_3.dll access
> it via IOCTLs. I believe this is the way it works on windows, although there
> doesn't seem to be any freely available documentation regarding the internal
> architecture. The XInput-HID backend could then create its own kernel object
> as a management interface, which could be accessed by xinput.cpl. This would
> have the added effect of having a single instance managing the xinput
> devices if several programs are running at the same time, which mimics the
> behavior of windows.
>
> What do you think would be the best option? Is there another way I haven't
> mentioned?
>
> - Juan
>
>
>
>