Nintendo 3DS
SDL Key
參考資訊：
1. libctru doc
2. 3ds-examples
3. SDL_sysjoystick
如下：
| 3DS Key | SDL Key |
|---|---|
| CPad X | JoystickAxis 0 |
| CPad Y | JoystickAxis 1 |
| A | JoystickButton 1 |
| B | JoystickButton 2 |
| X | JoystickButton 3 |
| Y | JoystickButton 4 |
| SELECT | JoystickButton 7 |
| START | JoystickButton 8 |
| L | JoystickButton 5 |
| R | JoystickButton 6 |