kc3-lang/SDL/src/joystick/dummy/SDL_sysjoystick.c

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• Hash : 345b4d7e
  Author :
  Date : 2020-05-29T13:37:21
  

  Fixed bug 5161 - Autodetect controller mappings based on the Linux Gamepad Specification Jan Bujak I wrote a new driver for my gamepad on Linux. I'd like SDL to support it out-of-box, as currently it just treats it as a generic joystick instead of a gamepad. From what I can see the only way to do that is to either 1) pick one of the already supported controllers' PID, VID and button layouts and have my driver send that (effectively lying that it's something else), or 2) submit a preconfigured, hardcoded mapping to SDL. Both of those, in my opinion, are silly when we already have the Linux Gamepad Specification which standarizes this: https://www.kernel.org/doc/html/v4.15/input/gamepad.html Unfortunately SDL doesn't make use of it currently. So I've took it upon myself to add it; patch is in the attachments. Basically what the patch does is that if SDL finds no built-it controller mappings for a given joystick it then asks the joystick backend to autodetect it, and that uses the relevant evdev bits to figure out which button/axis is which. (See the specs for more details.) With this patch applied my own driver for my controller works out-of-box with SDL with no extra configuration and is correctly recognized as a gamepad; this is also going to be the case for any other driver which follows the Linux Gamepad Specification.

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• src/joystick/dummy/SDL_sysjoystick.c

• /*
    Simple DirectMedia Layer
    Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
  
    This software is provided 'as-is', without any express or implied
    warranty.  In no event will the authors be held liable for any damages
    arising from the use of this software.
  
    Permission is granted to anyone to use this software for any purpose,
    including commercial applications, and to alter it and redistribute it
    freely, subject to the following restrictions:
  
    1. The origin of this software must not be misrepresented; you must not
       claim that you wrote the original software. If you use this software
       in a product, an acknowledgment in the product documentation would be
       appreciated but is not required.
    2. Altered source versions must be plainly marked as such, and must not be
       misrepresented as being the original software.
    3. This notice may not be removed or altered from any source distribution.
  */
  #include "../../SDL_internal.h"
  
  #if defined(SDL_JOYSTICK_DUMMY) || defined(SDL_JOYSTICK_DISABLED)
  
  /* This is the dummy implementation of the SDL joystick API */
  
  #include "SDL_joystick.h"
  #include "../SDL_sysjoystick.h"
  #include "../SDL_joystick_c.h"
  
  
  static int
  DUMMY_JoystickInit(void)
  {
      return 0;
  }
  
  static int
  DUMMY_JoystickGetCount(void)
  {
      return 0;
  }
  
  static void
  DUMMY_JoystickDetect(void)
  {
  }
  
  static const char *
  DUMMY_JoystickGetDeviceName(int device_index)
  {
      return NULL;
  }
  
  static int
  DUMMY_JoystickGetDevicePlayerIndex(int device_index)
  {
      return -1;
  }
  
  static void
  DUMMY_JoystickSetDevicePlayerIndex(int device_index, int player_index)
  {
  }
  
  static SDL_JoystickGUID
  DUMMY_JoystickGetDeviceGUID(int device_index)
  {
      SDL_JoystickGUID guid;
      SDL_zero(guid);
      return guid;
  }
  
  static SDL_JoystickID
  DUMMY_JoystickGetDeviceInstanceID(int device_index)
  {
      return -1;
  }
  
  static int
  DUMMY_JoystickOpen(SDL_Joystick * joystick, int device_index)
  {
      return SDL_SetError("Logic error: No joysticks available");
  }
  
  static int
  DUMMY_JoystickRumble(SDL_Joystick * joystick, Uint16 low_frequency_rumble, Uint16 high_frequency_rumble)
  {
      return SDL_Unsupported();
  }
  
  static void
  DUMMY_JoystickUpdate(SDL_Joystick * joystick)
  {
  }
  
  static void
  DUMMY_JoystickClose(SDL_Joystick * joystick)
  {
  }
  
  static void
  DUMMY_JoystickQuit(void)
  {
  }
  
  static SDL_bool
  DUMMY_JoystickGetGamepadMapping(int device_index, SDL_GamepadMapping *out)
  {
      return SDL_FALSE;
  }
  
  SDL_JoystickDriver SDL_DUMMY_JoystickDriver =
  {
      DUMMY_JoystickInit,
      DUMMY_JoystickGetCount,
      DUMMY_JoystickDetect,
      DUMMY_JoystickGetDeviceName,
      DUMMY_JoystickGetDevicePlayerIndex,
      DUMMY_JoystickSetDevicePlayerIndex,
      DUMMY_JoystickGetDeviceGUID,
      DUMMY_JoystickGetDeviceInstanceID,
      DUMMY_JoystickOpen,
      DUMMY_JoystickRumble,
      DUMMY_JoystickUpdate,
      DUMMY_JoystickClose,
      DUMMY_JoystickQuit,
      DUMMY_JoystickGetGamepadMapping
  };
  
  #endif /* SDL_JOYSTICK_DUMMY || SDL_JOYSTICK_DISABLED */
  
  /* vi: set ts=4 sw=4 expandtab: */
  

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