src/joystick/emscripten/SDL_sysjoystick.c - external/github.com/libsdl-org/SDL - Git at Google

 /*
   Simple DirectMedia Layer
   Copyright (C) 1997-2025 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"

 #ifdef SDL_JOYSTICK_EMSCRIPTEN

 #include <stdio.h> // For the definition of NULL

 #include "SDL_sysjoystick_c.h"
 #include "../SDL_joystick_c.h"

 static SDL_joylist_item *JoystickByIndex(int index);

 static SDL_joylist_item *SDL_joylist = NULL;
 static SDL_joylist_item *SDL_joylist_tail = NULL;
 static int numjoysticks = 0;

 static EM_BOOL Emscripten_JoyStickConnected(int eventType, const EmscriptenGamepadEvent *gamepadEvent, void *userData)
 {
     SDL_joylist_item *item;
     int i;

     SDL_LockJoysticks();

     if (JoystickByIndex(gamepadEvent->index) != NULL) {
         goto done;
     }

     item = (SDL_joylist_item *)SDL_malloc(sizeof(SDL_joylist_item));
     if (!item) {
         goto done;
     }

     SDL_zerop(item);
     item->index = gamepadEvent->index;

     item->name = SDL_CreateJoystickName(0, 0, NULL, gamepadEvent->id);
     if (!item->name) {
         SDL_free(item);
         goto done;
     }

     item->mapping = SDL_strdup(gamepadEvent->mapping);
     if (!item->mapping) {
         SDL_free(item->name);
         SDL_free(item);
         goto done;
     }

     item->naxes = gamepadEvent->numAxes;
     item->nbuttons = gamepadEvent->numButtons;
     item->device_instance = SDL_GetNextObjectID();

     item->timestamp = gamepadEvent->timestamp;

     for (i = 0; i < item->naxes; i++) {
         item->axis[i] = gamepadEvent->axis[i];
     }

     for (i = 0; i < item->nbuttons; i++) {
         item->analogButton[i] = gamepadEvent->analogButton[i];
         item->digitalButton[i] = gamepadEvent->digitalButton[i];
     }

     if (!SDL_joylist_tail) {
         SDL_joylist = SDL_joylist_tail = item;
     } else {
         SDL_joylist_tail->next = item;
         SDL_joylist_tail = item;
     }

     ++numjoysticks;

     SDL_PrivateJoystickAdded(item->device_instance);

 #ifdef DEBUG_JOYSTICK
     SDL_Log("Number of joysticks is %d", numjoysticks);
 #endif
 #ifdef DEBUG_JOYSTICK
     SDL_Log("Added joystick with index %d", item->index);
 #endif

 done:
     SDL_UnlockJoysticks();

     return 1;
 }

 static EM_BOOL Emscripten_JoyStickDisconnected(int eventType, const EmscriptenGamepadEvent *gamepadEvent, void *userData)
 {
     SDL_joylist_item *item = SDL_joylist;
     SDL_joylist_item *prev = NULL;

     SDL_LockJoysticks();

     while (item) {
         if (item->index == gamepadEvent->index) {
             break;
         }
         prev = item;
         item = item->next;
     }

     if (!item) {
         goto done;
     }

     if (item->joystick) {
         item->joystick->hwdata = NULL;
     }

     if (prev) {
         prev->next = item->next;
     } else {
         SDL_assert(SDL_joylist == item);
         SDL_joylist = item->next;
     }
     if (item == SDL_joylist_tail) {
         SDL_joylist_tail = prev;
     }

     // Need to decrement the joystick count before we post the event
     --numjoysticks;

     SDL_PrivateJoystickRemoved(item->device_instance);

 #ifdef DEBUG_JOYSTICK
     SDL_Log("Removed joystick with id %d", item->device_instance);
 #endif
     SDL_free(item->name);
     SDL_free(item->mapping);
     SDL_free(item);

 done:
     SDL_UnlockJoysticks();

     return 1;
 }

 // Function to perform any system-specific joystick related cleanup
 static void EMSCRIPTEN_JoystickQuit(void)
 {
     SDL_joylist_item *item = NULL;
     SDL_joylist_item *next = NULL;

     for (item = SDL_joylist; item; item = next) {
         next = item->next;
         SDL_free(item->mapping);
         SDL_free(item->name);
         SDL_free(item);
     }

     SDL_joylist = SDL_joylist_tail = NULL;

     numjoysticks = 0;

     emscripten_set_gamepadconnected_callback(NULL, 0, NULL);
     emscripten_set_gamepaddisconnected_callback(NULL, 0, NULL);
 }

 // Function to scan the system for joysticks.
 static bool EMSCRIPTEN_JoystickInit(void)
 {
     int rc, i, numjs;
     EmscriptenGamepadEvent gamepadState;

     numjoysticks = 0;

     rc = emscripten_sample_gamepad_data();

     // Check if gamepad is supported by browser
     if (rc == EMSCRIPTEN_RESULT_NOT_SUPPORTED) {
         return SDL_SetError("Gamepads not supported");
     }

     numjs = emscripten_get_num_gamepads();

     // handle already connected gamepads
     if (numjs > 0) {
         for (i = 0; i < numjs; i++) {
             rc = emscripten_get_gamepad_status(i, &gamepadState);
             if (rc == EMSCRIPTEN_RESULT_SUCCESS) {
                 Emscripten_JoyStickConnected(EMSCRIPTEN_EVENT_GAMEPADCONNECTED,
                                              &gamepadState,
                                              NULL);
             }
         }
     }

     rc = emscripten_set_gamepadconnected_callback(NULL,
                                                   0,
                                                   Emscripten_JoyStickConnected);

     if (rc != EMSCRIPTEN_RESULT_SUCCESS) {
         EMSCRIPTEN_JoystickQuit();
         return SDL_SetError("Could not set gamepad connect callback");
     }

     rc = emscripten_set_gamepaddisconnected_callback(NULL,
                                                          0,
                                                          Emscripten_JoyStickDisconnected);
     if (rc != EMSCRIPTEN_RESULT_SUCCESS) {
         EMSCRIPTEN_JoystickQuit();
         return SDL_SetError("Could not set gamepad disconnect callback");
     }

     return true;
 }

 // Returns item matching given SDL device index.
 static SDL_joylist_item *JoystickByDeviceIndex(int device_index)
 {
     SDL_joylist_item *item = SDL_joylist;

     while (0 < device_index) {
         --device_index;
         item = item->next;
     }

     return item;
 }

 // Returns item matching given HTML gamepad index.
 static SDL_joylist_item *JoystickByIndex(int index)
 {
     SDL_joylist_item *item = SDL_joylist;

     if (index < 0) {
         return NULL;
     }

     while (item) {
         if (item->index == index) {
             break;
         }
         item = item->next;
     }

     return item;
 }

 static int EMSCRIPTEN_JoystickGetCount(void)
 {
     return numjoysticks;
 }

 static void EMSCRIPTEN_JoystickDetect(void)
 {
 }

 static bool EMSCRIPTEN_JoystickIsDevicePresent(Uint16 vendor_id, Uint16 product_id, Uint16 version, const char *name)
 {
     // We don't override any other drivers
     return false;
 }

 static const char *EMSCRIPTEN_JoystickGetDeviceName(int device_index)
 {
     return JoystickByDeviceIndex(device_index)->name;
 }

 static const char *EMSCRIPTEN_JoystickGetDevicePath(int device_index)
 {
     return NULL;
 }

 static int EMSCRIPTEN_JoystickGetDeviceSteamVirtualGamepadSlot(int device_index)
 {
     return -1;
 }

 static int EMSCRIPTEN_JoystickGetDevicePlayerIndex(int device_index)
 {
     return -1;
 }

 static void EMSCRIPTEN_JoystickSetDevicePlayerIndex(int device_index, int player_index)
 {
 }

 static SDL_JoystickID EMSCRIPTEN_JoystickGetDeviceInstanceID(int device_index)
 {
     return JoystickByDeviceIndex(device_index)->device_instance;
 }

 static bool EMSCRIPTEN_JoystickOpen(SDL_Joystick *joystick, int device_index)
 {
     SDL_joylist_item *item = JoystickByDeviceIndex(device_index);
     bool rumble_available = false;

     if (!item) {
         return SDL_SetError("No such device");
     }

     if (item->joystick) {
         return SDL_SetError("Joystick already opened");
     }

     joystick->hwdata = (struct joystick_hwdata *)item;
     item->joystick = joystick;

     // HTML5 Gamepad API doesn't say anything about these
     joystick->nhats = 0;

     joystick->nbuttons = item->nbuttons;
     joystick->naxes = item->naxes;

     rumble_available = EM_ASM_INT({
         let gamepads = navigator['getGamepads']();
         if (!gamepads) {
             return 0;
         }
         let gamepad = gamepads[$0];
         if (!gamepad || !gamepad['vibrationActuator']) {
             return 0;
         }
         return 1;
         }, item->index);

     if (rumble_available) {
         SDL_SetBooleanProperty(SDL_GetJoystickProperties(joystick), SDL_PROP_JOYSTICK_CAP_RUMBLE_BOOLEAN, true);
     }

     return true;
 }

 /* Function to update the state of a joystick - called as a device poll.
  * This function shouldn't update the joystick structure directly,
  * but instead should call SDL_PrivateJoystick*() to deliver events
  * and update joystick device state.
  */
 static void EMSCRIPTEN_JoystickUpdate(SDL_Joystick *joystick)
 {
     EmscriptenGamepadEvent gamepadState;
     SDL_joylist_item *item = (SDL_joylist_item *)joystick->hwdata;
     int i, result;
     Uint64 timestamp = SDL_GetTicksNS();

     emscripten_sample_gamepad_data();

     if (item) {
         result = emscripten_get_gamepad_status(item->index, &gamepadState);
         if (result == EMSCRIPTEN_RESULT_SUCCESS) {
             if (gamepadState.timestamp == 0 || gamepadState.timestamp != item->timestamp) {
                 for (i = 0; i < item->nbuttons; i++) {
                     if (item->digitalButton[i] != gamepadState.digitalButton[i]) {
                         bool down = (gamepadState.digitalButton[i] != 0);
                         SDL_SendJoystickButton(timestamp, item->joystick, i, down);
                     }

                     // store values to compare them in the next update
                     item->analogButton[i] = gamepadState.analogButton[i];
                     item->digitalButton[i] = gamepadState.digitalButton[i];
                 }

                 for (i = 0; i < item->naxes; i++) {
                     if (item->axis[i] != gamepadState.axis[i]) {
                         // do we need to do conversion?
                         SDL_SendJoystickAxis(timestamp, item->joystick, i,
                                                 (Sint16)(32767. * gamepadState.axis[i]));
                     }

                     // store to compare in next update
                     item->axis[i] = gamepadState.axis[i];
                 }

                 item->timestamp = gamepadState.timestamp;
             }
         }
     }
 }

 // Function to close a joystick after use
 static void EMSCRIPTEN_JoystickClose(SDL_Joystick *joystick)
 {
     SDL_joylist_item *item = (SDL_joylist_item *)joystick->hwdata;
     if (item) {
         item->joystick = NULL;
     }
 }

 static SDL_GUID EMSCRIPTEN_JoystickGetDeviceGUID(int device_index)
 {
     // the GUID is just the name for now
     const char *name = EMSCRIPTEN_JoystickGetDeviceName(device_index);
     return SDL_CreateJoystickGUIDForName(name);
 }

 static bool EMSCRIPTEN_JoystickRumble(SDL_Joystick *joystick, Uint16 low_frequency_rumble, Uint16 high_frequency_rumble)
 {
     SDL_joylist_item *item = (SDL_joylist_item *)joystick->hwdata;

     // clang-format off
     bool result = EM_ASM_INT({
         let gamepads = navigator['getGamepads']();
         if (!gamepads) {
             return 0;
         }
         let gamepad = gamepads[$0];
         if (!gamepad || !gamepad['vibrationActuator']) {
             return 0;
         }

         gamepad['vibrationActuator']['playEffect']('dual-rumble', {
             'startDelay': 0,
             'duration': 3000,
             'weakMagnitude': $1 / 0xFFFF,
             'strongMagnitude': $2 / 0xFFFF,
         });
         return 1;
         }, item->index, low_frequency_rumble, high_frequency_rumble);

     return result;
 }

 static bool EMSCRIPTEN_JoystickRumbleTriggers(SDL_Joystick *joystick, Uint16 left_rumble, Uint16 right_rumble)
 {
     return SDL_Unsupported();
 }

 static bool EMSCRIPTEN_JoystickGetGamepadMapping(int device_index, SDL_GamepadMapping *out)
 {
     return false;
 }

 static bool EMSCRIPTEN_JoystickSetLED(SDL_Joystick *joystick, Uint8 red, Uint8 green, Uint8 blue)
 {
     return SDL_Unsupported();
 }

 static bool EMSCRIPTEN_JoystickSendEffect(SDL_Joystick *joystick, const void *data, int size)
 {
     return SDL_Unsupported();
 }

 static bool EMSCRIPTEN_JoystickSetSensorsEnabled(SDL_Joystick *joystick, bool enabled)
 {
     return SDL_Unsupported();
 }

 SDL_JoystickDriver SDL_EMSCRIPTEN_JoystickDriver = {
     EMSCRIPTEN_JoystickInit,
     EMSCRIPTEN_JoystickGetCount,
     EMSCRIPTEN_JoystickDetect,
     EMSCRIPTEN_JoystickIsDevicePresent,
     EMSCRIPTEN_JoystickGetDeviceName,
     EMSCRIPTEN_JoystickGetDevicePath,
     EMSCRIPTEN_JoystickGetDeviceSteamVirtualGamepadSlot,
     EMSCRIPTEN_JoystickGetDevicePlayerIndex,
     EMSCRIPTEN_JoystickSetDevicePlayerIndex,
     EMSCRIPTEN_JoystickGetDeviceGUID,
     EMSCRIPTEN_JoystickGetDeviceInstanceID,
     EMSCRIPTEN_JoystickOpen,
     EMSCRIPTEN_JoystickRumble,
     EMSCRIPTEN_JoystickRumbleTriggers,
     EMSCRIPTEN_JoystickSetLED,
     EMSCRIPTEN_JoystickSendEffect,
     EMSCRIPTEN_JoystickSetSensorsEnabled,
     EMSCRIPTEN_JoystickUpdate,
     EMSCRIPTEN_JoystickClose,
     EMSCRIPTEN_JoystickQuit,
     EMSCRIPTEN_JoystickGetGamepadMapping
 };

 #endif // SDL_JOYSTICK_EMSCRIPTEN
	/*
	Simple DirectMedia Layer
	Copyright (C) 1997-2025 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"

	#ifdef SDL_JOYSTICK_EMSCRIPTEN

	#include <stdio.h> // For the definition of NULL

	#include "SDL_sysjoystick_c.h"
	#include "../SDL_joystick_c.h"

	static SDL_joylist_item *JoystickByIndex(int index);

	static SDL_joylist_item *SDL_joylist = NULL;
	static SDL_joylist_item *SDL_joylist_tail = NULL;
	static int numjoysticks = 0;

	static EM_BOOL Emscripten_JoyStickConnected(int eventType, const EmscriptenGamepadEvent gamepadEvent, void userData)
	{
	SDL_joylist_item *item;
	int i;

	SDL_LockJoysticks();

	if (JoystickByIndex(gamepadEvent->index) != NULL) {
	goto done;
	}

	item = (SDL_joylist_item *)SDL_malloc(sizeof(SDL_joylist_item));
	if (!item) {
	goto done;
	}

	SDL_zerop(item);
	item->index = gamepadEvent->index;

	item->name = SDL_CreateJoystickName(0, 0, NULL, gamepadEvent->id);
	if (!item->name) {
	SDL_free(item);
	goto done;
	}

	item->mapping = SDL_strdup(gamepadEvent->mapping);
	if (!item->mapping) {
	SDL_free(item->name);
	SDL_free(item);
	goto done;
	}

	item->naxes = gamepadEvent->numAxes;
	item->nbuttons = gamepadEvent->numButtons;
	item->device_instance = SDL_GetNextObjectID();

	item->timestamp = gamepadEvent->timestamp;

	for (i = 0; i < item->naxes; i++) {
	item->axis[i] = gamepadEvent->axis[i];
	}

	for (i = 0; i < item->nbuttons; i++) {
	item->analogButton[i] = gamepadEvent->analogButton[i];
	item->digitalButton[i] = gamepadEvent->digitalButton[i];
	}

	if (!SDL_joylist_tail) {
	SDL_joylist = SDL_joylist_tail = item;
	} else {
	SDL_joylist_tail->next = item;
	SDL_joylist_tail = item;
	}

	++numjoysticks;

	SDL_PrivateJoystickAdded(item->device_instance);

	#ifdef DEBUG_JOYSTICK
	SDL_Log("Number of joysticks is %d", numjoysticks);
	#endif
	#ifdef DEBUG_JOYSTICK
	SDL_Log("Added joystick with index %d", item->index);
	#endif

	done:
	SDL_UnlockJoysticks();

	return 1;
	}

	static EM_BOOL Emscripten_JoyStickDisconnected(int eventType, const EmscriptenGamepadEvent gamepadEvent, void userData)
	{
	SDL_joylist_item *item = SDL_joylist;
	SDL_joylist_item *prev = NULL;

	SDL_LockJoysticks();

	while (item) {
	if (item->index == gamepadEvent->index) {
	break;
	}
	prev = item;
	item = item->next;
	}

	if (!item) {
	goto done;
	}

	if (item->joystick) {
	item->joystick->hwdata = NULL;
	}

	if (prev) {
	prev->next = item->next;
	} else {
	SDL_assert(SDL_joylist == item);
	SDL_joylist = item->next;
	}
	if (item == SDL_joylist_tail) {
	SDL_joylist_tail = prev;
	}

	// Need to decrement the joystick count before we post the event
	--numjoysticks;

	SDL_PrivateJoystickRemoved(item->device_instance);

	#ifdef DEBUG_JOYSTICK
	SDL_Log("Removed joystick with id %d", item->device_instance);
	#endif
	SDL_free(item->name);
	SDL_free(item->mapping);
	SDL_free(item);

	done:
	SDL_UnlockJoysticks();

	return 1;
	}

	// Function to perform any system-specific joystick related cleanup
	static void EMSCRIPTEN_JoystickQuit(void)
	{
	SDL_joylist_item *item = NULL;
	SDL_joylist_item *next = NULL;

	for (item = SDL_joylist; item; item = next) {
	next = item->next;
	SDL_free(item->mapping);
	SDL_free(item->name);
	SDL_free(item);
	}

	SDL_joylist = SDL_joylist_tail = NULL;

	numjoysticks = 0;

	emscripten_set_gamepadconnected_callback(NULL, 0, NULL);
	emscripten_set_gamepaddisconnected_callback(NULL, 0, NULL);
	}

	// Function to scan the system for joysticks.
	static bool EMSCRIPTEN_JoystickInit(void)
	{
	int rc, i, numjs;
	EmscriptenGamepadEvent gamepadState;

	numjoysticks = 0;

	rc = emscripten_sample_gamepad_data();

	// Check if gamepad is supported by browser
	if (rc == EMSCRIPTEN_RESULT_NOT_SUPPORTED) {
	return SDL_SetError("Gamepads not supported");
	}

	numjs = emscripten_get_num_gamepads();

	// handle already connected gamepads
	if (numjs > 0) {
	for (i = 0; i < numjs; i++) {
	rc = emscripten_get_gamepad_status(i, &gamepadState);
	if (rc == EMSCRIPTEN_RESULT_SUCCESS) {
	Emscripten_JoyStickConnected(EMSCRIPTEN_EVENT_GAMEPADCONNECTED,
	&gamepadState,
	NULL);
	}
	}
	}

	rc = emscripten_set_gamepadconnected_callback(NULL,
	0,
	Emscripten_JoyStickConnected);

	if (rc != EMSCRIPTEN_RESULT_SUCCESS) {
	EMSCRIPTEN_JoystickQuit();
	return SDL_SetError("Could not set gamepad connect callback");
	}

	rc = emscripten_set_gamepaddisconnected_callback(NULL,
	0,
	Emscripten_JoyStickDisconnected);
	if (rc != EMSCRIPTEN_RESULT_SUCCESS) {
	EMSCRIPTEN_JoystickQuit();
	return SDL_SetError("Could not set gamepad disconnect callback");
	}

	return true;
	}

	// Returns item matching given SDL device index.
	static SDL_joylist_item *JoystickByDeviceIndex(int device_index)
	{
	SDL_joylist_item *item = SDL_joylist;

	while (0 < device_index) {
	--device_index;
	item = item->next;
	}

	return item;
	}

	// Returns item matching given HTML gamepad index.
	static SDL_joylist_item *JoystickByIndex(int index)
	{
	SDL_joylist_item *item = SDL_joylist;

	if (index < 0) {
	return NULL;
	}

	while (item) {
	if (item->index == index) {
	break;
	}
	item = item->next;
	}

	return item;
	}

	static int EMSCRIPTEN_JoystickGetCount(void)
	{
	return numjoysticks;
	}

	static void EMSCRIPTEN_JoystickDetect(void)
	{
	}

	static bool EMSCRIPTEN_JoystickIsDevicePresent(Uint16 vendor_id, Uint16 product_id, Uint16 version, const char *name)
	{
	// We don't override any other drivers
	return false;
	}

	static const char *EMSCRIPTEN_JoystickGetDeviceName(int device_index)
	{
	return JoystickByDeviceIndex(device_index)->name;
	}

	static const char *EMSCRIPTEN_JoystickGetDevicePath(int device_index)
	{
	return NULL;
	}

	static int EMSCRIPTEN_JoystickGetDeviceSteamVirtualGamepadSlot(int device_index)
	{
	return -1;
	}

	static int EMSCRIPTEN_JoystickGetDevicePlayerIndex(int device_index)
	{
	return -1;
	}

	static void EMSCRIPTEN_JoystickSetDevicePlayerIndex(int device_index, int player_index)
	{
	}

	static SDL_JoystickID EMSCRIPTEN_JoystickGetDeviceInstanceID(int device_index)
	{
	return JoystickByDeviceIndex(device_index)->device_instance;
	}

	static bool EMSCRIPTEN_JoystickOpen(SDL_Joystick *joystick, int device_index)
	{
	SDL_joylist_item *item = JoystickByDeviceIndex(device_index);
	bool rumble_available = false;

	if (!item) {
	return SDL_SetError("No such device");
	}

	if (item->joystick) {
	return SDL_SetError("Joystick already opened");
	}

	joystick->hwdata = (struct joystick_hwdata *)item;
	item->joystick = joystick;

	// HTML5 Gamepad API doesn't say anything about these
	joystick->nhats = 0;

	joystick->nbuttons = item->nbuttons;
	joystick->naxes = item->naxes;

	rumble_available = EM_ASM_INT({
	let gamepads = navigator['getGamepads']();
	if (!gamepads) {
	return 0;
	}
	let gamepad = gamepads[$0];
	if (!gamepad \|\| !gamepad['vibrationActuator']) {
	return 0;
	}
	return 1;
	}, item->index);

	if (rumble_available) {
	SDL_SetBooleanProperty(SDL_GetJoystickProperties(joystick), SDL_PROP_JOYSTICK_CAP_RUMBLE_BOOLEAN, true);
	}

	return true;
	}

	/* Function to update the state of a joystick - called as a device poll.
	* This function shouldn't update the joystick structure directly,
	* but instead should call SDL_PrivateJoystick*() to deliver events
	* and update joystick device state.
	*/
	static void EMSCRIPTEN_JoystickUpdate(SDL_Joystick *joystick)
	{
	EmscriptenGamepadEvent gamepadState;
	SDL_joylist_item item = (SDL_joylist_item )joystick->hwdata;
	int i, result;
	Uint64 timestamp = SDL_GetTicksNS();

	emscripten_sample_gamepad_data();

	if (item) {
	result = emscripten_get_gamepad_status(item->index, &gamepadState);
	if (result == EMSCRIPTEN_RESULT_SUCCESS) {
	if (gamepadState.timestamp == 0 \|\| gamepadState.timestamp != item->timestamp) {
	for (i = 0; i < item->nbuttons; i++) {
	if (item->digitalButton[i] != gamepadState.digitalButton[i]) {
	bool down = (gamepadState.digitalButton[i] != 0);
	SDL_SendJoystickButton(timestamp, item->joystick, i, down);
	}

	// store values to compare them in the next update
	item->analogButton[i] = gamepadState.analogButton[i];
	item->digitalButton[i] = gamepadState.digitalButton[i];
	}

	for (i = 0; i < item->naxes; i++) {
	if (item->axis[i] != gamepadState.axis[i]) {
	// do we need to do conversion?
	SDL_SendJoystickAxis(timestamp, item->joystick, i,
	(Sint16)(32767. * gamepadState.axis[i]));
	}

	// store to compare in next update
	item->axis[i] = gamepadState.axis[i];
	}

	item->timestamp = gamepadState.timestamp;
	}
	}
	}
	}

	// Function to close a joystick after use
	static void EMSCRIPTEN_JoystickClose(SDL_Joystick *joystick)
	{
	SDL_joylist_item item = (SDL_joylist_item )joystick->hwdata;
	if (item) {
	item->joystick = NULL;
	}
	}

	static SDL_GUID EMSCRIPTEN_JoystickGetDeviceGUID(int device_index)
	{
	// the GUID is just the name for now
	const char *name = EMSCRIPTEN_JoystickGetDeviceName(device_index);
	return SDL_CreateJoystickGUIDForName(name);
	}

	static bool EMSCRIPTEN_JoystickRumble(SDL_Joystick *joystick, Uint16 low_frequency_rumble, Uint16 high_frequency_rumble)
	{
	SDL_joylist_item item = (SDL_joylist_item )joystick->hwdata;

	// clang-format off
	bool result = EM_ASM_INT({
	let gamepads = navigator['getGamepads']();
	if (!gamepads) {
	return 0;
	}
	let gamepad = gamepads[$0];
	if (!gamepad \|\| !gamepad['vibrationActuator']) {
	return 0;
	}

	gamepad['vibrationActuator']['playEffect']('dual-rumble', {
	'startDelay': 0,
	'duration': 3000,
	'weakMagnitude': $1 / 0xFFFF,
	'strongMagnitude': $2 / 0xFFFF,
	});
	return 1;
	}, item->index, low_frequency_rumble, high_frequency_rumble);

	return result;
	}

	static bool EMSCRIPTEN_JoystickRumbleTriggers(SDL_Joystick *joystick, Uint16 left_rumble, Uint16 right_rumble)
	{
	return SDL_Unsupported();
	}

	static bool EMSCRIPTEN_JoystickGetGamepadMapping(int device_index, SDL_GamepadMapping *out)
	{
	return false;
	}

	static bool EMSCRIPTEN_JoystickSetLED(SDL_Joystick *joystick, Uint8 red, Uint8 green, Uint8 blue)
	{
	return SDL_Unsupported();
	}

	static bool EMSCRIPTEN_JoystickSendEffect(SDL_Joystick joystick, const void data, int size)
	{
	return SDL_Unsupported();
	}

	static bool EMSCRIPTEN_JoystickSetSensorsEnabled(SDL_Joystick *joystick, bool enabled)
	{
	return SDL_Unsupported();
	}

	SDL_JoystickDriver SDL_EMSCRIPTEN_JoystickDriver = {
	EMSCRIPTEN_JoystickInit,
	EMSCRIPTEN_JoystickGetCount,
	EMSCRIPTEN_JoystickDetect,
	EMSCRIPTEN_JoystickIsDevicePresent,
	EMSCRIPTEN_JoystickGetDeviceName,
	EMSCRIPTEN_JoystickGetDevicePath,
	EMSCRIPTEN_JoystickGetDeviceSteamVirtualGamepadSlot,
	EMSCRIPTEN_JoystickGetDevicePlayerIndex,
	EMSCRIPTEN_JoystickSetDevicePlayerIndex,
	EMSCRIPTEN_JoystickGetDeviceGUID,
	EMSCRIPTEN_JoystickGetDeviceInstanceID,
	EMSCRIPTEN_JoystickOpen,
	EMSCRIPTEN_JoystickRumble,
	EMSCRIPTEN_JoystickRumbleTriggers,
	EMSCRIPTEN_JoystickSetLED,
	EMSCRIPTEN_JoystickSendEffect,
	EMSCRIPTEN_JoystickSetSensorsEnabled,
	EMSCRIPTEN_JoystickUpdate,
	EMSCRIPTEN_JoystickClose,
	EMSCRIPTEN_JoystickQuit,
	EMSCRIPTEN_JoystickGetGamepadMapping
	};

	#endif // SDL_JOYSTICK_EMSCRIPTEN