src/joystick/darwin/SDL_sysjoystick.c
author Sam Lantinga <slouken@libsdl.org>
Tue, 16 Oct 2001 15:01:37 +0000
changeset 208 ab4abaf66814
parent 196 c4c4b221a5e5
child 209 c995b877bc5b
permissions -rw-r--r--
*** empty log message ***
     1 /*
     2 	SDL - Simple DirectMedia Layer
     3 	Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga
     4 
     5 	This library is free software; you can redistribute it and/or
     6 	modify it under the terms of the GNU Library General Public
     7 	License as published by the Free Software Foundation; either
     8 	version 2 of the License, or (at your option) any later version.
     9 
    10 	This library is distributed in the hope that it will be useful,
    11 	but WITHOUT ANY WARRANTY; without even the implied warranty of
    12 	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13 	Library General Public License for more details.
    14 
    15 	You should have received a copy of the GNU Library General Public
    16 	License along with this library; if not, write to the Free
    17 	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    18 
    19 	Sam Lantinga
    20 	slouken@devolution.com
    21 */
    22 
    23 /* SDL joystick driver for Darwin / MacOS X, based on the IOKit HID API */
    24 /* Written 2001 by Max Horn */
    25 
    26 #include <stdio.h>
    27 #include <stdlib.h>
    28 #include <unistd.h>
    29 #include <ctype.h>
    30 #include <sys/errno.h>
    31 #include <sysexits.h>
    32 #include <mach/mach.h>
    33 #include <mach/mach_error.h>
    34 #include <IOKit/IOKitLib.h>
    35 #include <IOKit/IOCFPlugIn.h>
    36 #include <Kernel/IOKit/hidsystem/IOHIDUsageTables.h>
    37 #include <IOKit/hid/IOHIDLib.h>
    38 #include <IOKit/hid/IOHIDKeys.h>
    39 #include <CoreFoundation/CoreFoundation.h>
    40 
    41 #include "SDL_error.h"
    42 #include "SDL_joystick.h"
    43 #include "SDL_sysjoystick.h"
    44 #include "SDL_joystick_c.h"
    45 
    46 struct recElement
    47 {
    48 	IOHIDElementCookie cookie;				// unique value which identifies element, will NOT change
    49 	long min;								// reported min value possible
    50 	long max;								// reported max value possible
    51 /*
    52 	TODO: maybe should handle the following stuff somehow?
    53 
    54 	long scaledMin;							// reported scaled min value possible
    55 	long scaledMax;							// reported scaled max value possible
    56 	long size;								// size in bits of data return from element
    57 	Boolean relative;						// are reports relative to last report (deltas)
    58 	Boolean wrapping;						// does element wrap around (one value higher than max is min)
    59 	Boolean nonLinear;						// are the values reported non-linear relative to element movement
    60 	Boolean preferredState;					// does element have a preferred state (such as a button)
    61 	Boolean nullState;						// does element have null state
    62 */
    63 
    64 	/* runtime variables used for auto-calibration */
    65 	long minReport;							// min returned value
    66 	long maxReport;							// max returned value
    67 	
    68 	struct recElement * pNext;				// next element in list
    69 };
    70 typedef struct recElement recElement;
    71 
    72 struct joystick_hwdata
    73 {
    74 	IOHIDDeviceInterface ** interface;		// interface to device, NULL = no interface
    75 
    76 	char product[256];							// name of product
    77 	long usage;								// usage page from IOUSBHID Parser.h which defines general usage
    78 	long usagePage;							// usage within above page from IOUSBHID Parser.h which defines specific usage
    79 
    80 	long axes;								// number of axis (calculated, not reported by device)
    81 	long buttons;							// number of buttons (calculated, not reported by device)
    82 	long hats;								// number of hat switches (calculated, not reported by device)
    83 	long elements;							// number of total elements (shouldbe total of above) (calculated, not reported by device)
    84 
    85 	recElement* firstAxis;
    86 	recElement* firstButton;
    87 	recElement* firstHat;
    88 
    89 	struct recDevice* pNext;				// next device
    90 };
    91 typedef struct joystick_hwdata recDevice;
    92 
    93 
    94 /* Linked list of all available devices */
    95 static recDevice *gpDeviceList = NULL;
    96 
    97 
    98 void HIDReportErrorNum (char * strError, long numError)
    99 {
   100 	SDL_SetError(strError);
   101 }
   102 
   103 static void HIDGetCollectionElements (CFMutableDictionaryRef deviceProperties, recDevice *pDevice);
   104 
   105 /* returns current value for element, polling element
   106  * will return 0 on error conditions which should be accounted for by application
   107  */
   108 
   109 SInt32 HIDGetElementValue (recDevice *pDevice, recElement *pElement)
   110 {
   111 	IOReturn result = kIOReturnSuccess;
   112 	IOHIDEventStruct hidEvent;
   113 	hidEvent.value = 0;
   114 	
   115 	if (NULL != pDevice && NULL != pElement && NULL != pDevice->interface)
   116 	{
   117 		result = (*(pDevice->interface))->getElementValue(pDevice->interface, pElement->cookie, &hidEvent);
   118 		if (kIOReturnSuccess == result)
   119 		{
   120 			/* record min and max for auto calibration */
   121 			if (hidEvent.value < pElement->minReport)
   122 				pElement->minReport = hidEvent.value;
   123 			if (hidEvent.value > pElement->maxReport)
   124 				pElement->maxReport = hidEvent.value;
   125 		}
   126 	}
   127 
   128 	// auto user scale
   129 	return hidEvent.value;
   130 }
   131 
   132 /* similiar to HIDGetElementValue, but auto-calibrates the value before returning it */
   133 
   134 SInt32 HIDCalibratedValue (recDevice *pDevice, recElement *pElement)
   135 {
   136 	float deviceScale = pElement->max - pElement->min;
   137 	float readScale = pElement->maxReport - pElement->minReport;
   138 	SInt32 value = HIDGetElementValue(pDevice, pElement);
   139 	if (readScale == 0)
   140 		return value; // no scaling at all
   141 	else
   142 		return ((value - pElement->minReport) * deviceScale / readScale) + pElement->min;
   143 }
   144 
   145 /* similiar to HIDCalibratedValue but calibrates to an arbitrary scale instead of the elements default scale */
   146 
   147 SInt32 HIDScaledCalibratedValue (recDevice *pDevice, recElement *pElement, long min, long max)
   148 {
   149 	float deviceScale = max - min;
   150 	float readScale = pElement->maxReport - pElement->minReport;
   151 	SInt32 value = HIDGetElementValue(pDevice, pElement);
   152 	if (readScale == 0)
   153 		return value; // no scaling at all
   154 	else
   155 		return ((value - pElement->minReport) * deviceScale / readScale) + min;
   156 }
   157 
   158 /* Create and open an interface to device, required prior to extracting values or building queues.
   159  * Note: appliction now owns the device and must close and release it prior to exiting
   160  */
   161 
   162 IOReturn HIDCreateOpenDeviceInterface (io_object_t hidDevice, recDevice *pDevice)
   163 {
   164 	IOReturn result = kIOReturnSuccess;
   165 	HRESULT plugInResult = S_OK;
   166 	SInt32 score = 0;
   167 	IOCFPlugInInterface ** ppPlugInInterface = NULL;
   168 	
   169 	if (NULL == pDevice->interface)
   170 	{
   171 		result = IOCreatePlugInInterfaceForService (hidDevice, kIOHIDDeviceUserClientTypeID,
   172 													kIOCFPlugInInterfaceID, &ppPlugInInterface, &score);
   173 		if (kIOReturnSuccess == result)
   174 		{
   175 			// Call a method of the intermediate plug-in to create the device interface
   176 			plugInResult = (*ppPlugInInterface)->QueryInterface (ppPlugInInterface,
   177 								CFUUIDGetUUIDBytes (kIOHIDDeviceInterfaceID), (void *) &(pDevice->interface));
   178 			if (S_OK != plugInResult)
   179 				HIDReportErrorNum ("CouldnŐt query HID class device interface from plugInInterface", plugInResult);
   180 			(*ppPlugInInterface)->Release (ppPlugInInterface);
   181 		}
   182 		else
   183 			HIDReportErrorNum ("Failed to create **plugInInterface via IOCreatePlugInInterfaceForService.", result);
   184 	}
   185 	if (NULL != pDevice->interface)
   186 	{
   187 		result = (*(pDevice->interface))->open (pDevice->interface, 0);
   188 		if (kIOReturnSuccess != result)
   189 			HIDReportErrorNum ("Failed to open pDevice->interface via open.", result);
   190 	}
   191 	return result;
   192 }
   193 
   194 /* Closes and releases interface to device, should be done prior to exting application
   195  * Note: will have no affect if device or interface do not exist
   196  * application will "own" the device if interface is not closed
   197  * (device may have to be plug and re-plugged in different location to get it working again without a restart)
   198  */
   199 
   200 IOReturn HIDCloseReleaseInterface (recDevice *pDevice)
   201 {
   202 	IOReturn result = kIOReturnSuccess;
   203 	
   204 	if ((NULL != pDevice) && (NULL != pDevice->interface))
   205 	{
   206 		// close the interface
   207 		result = (*(pDevice->interface))->close (pDevice->interface);
   208 		if (kIOReturnNotOpen == result)
   209 		{
   210 			//  do nothing as device was not opened, thus can't be closed
   211 		}
   212 		else if (kIOReturnSuccess != result)
   213 			HIDReportErrorNum ("Failed to close IOHIDDeviceInterface.", result);
   214 		//release the interface
   215 		result = (*(pDevice->interface))->Release (pDevice->interface);
   216 		if (kIOReturnSuccess != result)
   217 			HIDReportErrorNum ("Failed to release IOHIDDeviceInterface.", result);
   218 		pDevice->interface = NULL;
   219 	}	
   220 	return result;
   221 }
   222 
   223 /* extracts actual specific element information from each element CF dictionary entry */
   224 
   225 static void HIDGetElementInfo (CFTypeRef refElement, recElement *pElement)
   226 {
   227 	long number;
   228 	CFTypeRef refType;
   229 
   230 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementCookieKey));
   231 	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
   232 		pElement->cookie = (IOHIDElementCookie) number;
   233 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementMinKey));
   234 	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
   235 		pElement->min = number;
   236 		pElement->maxReport = pElement->min;
   237 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementMaxKey));
   238 	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
   239 		pElement->max = number;
   240 		pElement->minReport = pElement->max;
   241 /*
   242 	TODO: maybe should handle the following stuff somehow?
   243 
   244 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementScaledMinKey));
   245 	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
   246 		pElement->scaledMin = number;
   247 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementScaledMaxKey));
   248 	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
   249 		pElement->scaledMax = number;
   250 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementSizeKey));
   251 	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
   252 		pElement->size = number;
   253 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementIsRelativeKey));
   254 	if (refType)
   255 		pElement->relative = CFBooleanGetValue (refType);
   256 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementIsWrappingKey));
   257 	if (refType)
   258 		pElement->wrapping = CFBooleanGetValue (refType);
   259 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementIsNonLinearKey));
   260 	if (refType)
   261 		pElement->nonLinear = CFBooleanGetValue (refType);
   262 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementHasPreferedStateKey));
   263 	if (refType)
   264 		pElement->preferredState = CFBooleanGetValue (refType);
   265 	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementHasNullStateKey));
   266 	if (refType)
   267 		pElement->nullState = CFBooleanGetValue (refType);
   268 */
   269 }			
   270 
   271 /* examines CF dictionary vlaue in device element hierarchy to determine if it is element of interest or a collection of more elements
   272  * if element of interest allocate storage, add to list and retrieve element specific info
   273  * if collection then pass on to deconstruction collection into additional individual elements
   274  */
   275 
   276 static void HIDAddElement (CFTypeRef refElement, recDevice* pDevice)
   277 {
   278 	recElement* element = NULL;
   279 	recElement** headElement = NULL;
   280 	long elementType, usagePage, usage;
   281 	CFTypeRef refElementType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementTypeKey));
   282 	CFTypeRef refUsagePage = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementUsagePageKey));
   283 	CFTypeRef refUsage = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementUsageKey));
   284 
   285 
   286 	if ((refElementType) && (CFNumberGetValue (refElementType, kCFNumberLongType, &elementType)))
   287 	{
   288 		/* look at types of interest */
   289 		if ((elementType == kIOHIDElementTypeInput_Misc) || (elementType == kIOHIDElementTypeInput_Button) ||
   290 			(elementType == kIOHIDElementTypeInput_Axis))
   291 		{
   292 			if (refUsagePage && CFNumberGetValue (refUsagePage, kCFNumberLongType, &usagePage) &&
   293 				refUsage && CFNumberGetValue (refUsage, kCFNumberLongType, &usage))
   294 			{
   295 				switch (usagePage) /* only interested in kHIDPage_GenericDesktop and kHIDPage_Button */
   296 				{
   297 					case kHIDPage_GenericDesktop:
   298 						{
   299 							switch (usage) /* look at usage to determine function */
   300 							{
   301 								case kHIDUsage_GD_X:
   302 								case kHIDUsage_GD_Y:
   303 								case kHIDUsage_GD_Z:
   304 								case kHIDUsage_GD_Rx:
   305 								case kHIDUsage_GD_Ry:
   306 								case kHIDUsage_GD_Rz:
   307 									element = (recElement *) NewPtrClear (sizeof (recElement));
   308 									if (element)
   309 									{
   310 										pDevice->axes++;
   311 										headElement = &(pDevice->firstAxis);
   312 									}
   313 								break;
   314 								case kHIDUsage_GD_Hatswitch:
   315 									element = (recElement *) NewPtrClear (sizeof (recElement));
   316 									if (element)
   317 									{
   318 										pDevice->hats++;
   319 										headElement = &(pDevice->firstHat);
   320 									}
   321 								break;
   322 							}							
   323 						}
   324 						break;
   325 					case kHIDPage_Button:
   326 						element = (recElement *) NewPtrClear (sizeof (recElement));
   327 						if (element)
   328 						{
   329 							pDevice->buttons++;
   330 							headElement = &(pDevice->firstButton);
   331 						}
   332 						break;
   333 					default:
   334 						break;
   335 				}
   336 			}
   337 		}
   338 		else if (kIOHIDElementTypeCollection == elementType)
   339 			HIDGetCollectionElements ((CFMutableDictionaryRef) refElement, pDevice);
   340 	}
   341 
   342 	if (element && headElement) /* add to list */
   343 	{
   344 		pDevice->elements++;
   345 		if (NULL == *headElement)
   346 			*headElement = element;
   347 		else
   348 		{
   349 			recElement *elementPrevious, *elementCurrent;
   350 			elementCurrent = *headElement;
   351 			while (elementCurrent)
   352 			{
   353 				elementPrevious = elementCurrent;
   354 				elementCurrent = elementPrevious->pNext;
   355 			}
   356 			elementPrevious->pNext = element;
   357 		}
   358 		element->pNext = NULL;
   359 		HIDGetElementInfo (refElement, element);
   360 	}
   361 }
   362 
   363 /* collects information from each array member in device element list (each array memeber = element) */
   364 
   365 static void HIDGetElementsCFArrayHandler (const void * value, void * parameter)
   366 {
   367 	if (CFGetTypeID (value) == CFDictionaryGetTypeID ())
   368 		HIDAddElement ((CFTypeRef) value, (recDevice *) parameter);
   369 }
   370 
   371 /* handles retrieval of element information from arrays of elements in device IO registry information */
   372 
   373 static void HIDGetElements (CFTypeRef refElementCurrent, recDevice *pDevice)
   374 {
   375 	CFTypeID type = CFGetTypeID (refElementCurrent);
   376 	if (type == CFArrayGetTypeID()) /* if element is an array */
   377 	{
   378 		CFRange range = {0, CFArrayGetCount (refElementCurrent)};
   379 		/* CountElementsCFArrayHandler called for each array member */
   380 		CFArrayApplyFunction (refElementCurrent, range, HIDGetElementsCFArrayHandler, pDevice);
   381 	}
   382 }			
   383 
   384 /* handles extracting element information from element collection CF types
   385  * used from top level element decoding and hierarchy deconstruction to flatten device element list
   386  */
   387 
   388 static void HIDGetCollectionElements (CFMutableDictionaryRef deviceProperties, recDevice *pDevice)
   389 {
   390 	CFTypeRef refElementTop = CFDictionaryGetValue (deviceProperties, CFSTR(kIOHIDElementKey));
   391 	if (refElementTop)
   392 		HIDGetElements (refElementTop, pDevice);
   393 }
   394 
   395 /* use top level element usage page and usage to discern device usage page and usage setting appropriate vlaues in device record */
   396 
   397 static void HIDTopLevelElementHandler (const void * value, void * parameter)
   398 {
   399 	CFTypeRef refCF = 0;
   400 	if (CFGetTypeID (value) != CFDictionaryGetTypeID ())
   401 		return;
   402 	refCF = CFDictionaryGetValue (value, CFSTR(kIOHIDElementUsagePageKey));
   403 	if (!CFNumberGetValue (refCF, kCFNumberLongType, &((recDevice *) parameter)->usagePage))
   404 		SDL_SetError ("CFNumberGetValue error retrieving pDevice->usagePage.");
   405 	refCF = CFDictionaryGetValue (value, CFSTR(kIOHIDElementUsageKey));
   406 	if (!CFNumberGetValue (refCF, kCFNumberLongType, &((recDevice *) parameter)->usage))
   407 		SDL_SetError ("CFNumberGetValue error retrieving pDevice->usage.");
   408 }
   409 
   410 /* extracts device info from CF dictionary records in IO registry */
   411 
   412 static void HIDGetDeviceInfo (io_object_t hidDevice, CFMutableDictionaryRef hidProperties, recDevice *pDevice)
   413 {
   414 	CFMutableDictionaryRef usbProperties = 0;
   415 	io_registry_entry_t parent1, parent2;
   416 	
   417 	/* Mac OS X currently is not mirroring all USB properties to HID page so need to look at USB device page also
   418 	 * get dictionary for usb properties: step up two levels and get CF dictionary for USB properties
   419 	 */
   420 	if ((KERN_SUCCESS == IORegistryEntryGetParentEntry (hidDevice, kIOServicePlane, &parent1)) &&
   421 		(KERN_SUCCESS == IORegistryEntryGetParentEntry (parent1, kIOServicePlane, &parent2)) &&
   422 		(KERN_SUCCESS == IORegistryEntryCreateCFProperties (parent2, &usbProperties, kCFAllocatorDefault, kNilOptions)))
   423 	{
   424 		if (usbProperties)
   425 		{
   426 			CFTypeRef refCF = 0;
   427 			/* get device info
   428 			 * try hid dictionary first, if fail then go to usb dictionary
   429 			 */
   430 			
   431 			
   432 			/* get product name */
   433 			refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDProductKey));
   434 			if (!refCF)
   435 				refCF = CFDictionaryGetValue (usbProperties, CFSTR("USB Product Name"));
   436 			if (refCF)
   437 			{
   438 				if (!CFStringGetCString (refCF, pDevice->product, 256, CFStringGetSystemEncoding ()))
   439 					SDL_SetError ("CFStringGetCString error retrieving pDevice->product.");
   440 			}
   441 			
   442 			/* get usage page and usage */
   443 			refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDPrimaryUsagePageKey));
   444 			if (refCF)
   445 			{
   446 				if (!CFNumberGetValue (refCF, kCFNumberLongType, &pDevice->usagePage))
   447 					SDL_SetError ("CFNumberGetValue error retrieving pDevice->usagePage.");
   448 				refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDPrimaryUsageKey));
   449 				if (refCF)
   450 					if (!CFNumberGetValue (refCF, kCFNumberLongType, &pDevice->usage))
   451 						SDL_SetError ("CFNumberGetValue error retrieving pDevice->usage.");
   452 			}
   453 
   454 			if (NULL == refCF) /* get top level element HID usage page or usage */
   455 			{
   456 				/* use top level element instead */
   457 				CFTypeRef refCFTopElement = 0;
   458 				refCFTopElement = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDElementKey));
   459 				{
   460 					/* refCFTopElement points to an array of element dictionaries */
   461 					CFRange range = {0, CFArrayGetCount (refCFTopElement)};
   462 					CFArrayApplyFunction (refCFTopElement, range, HIDTopLevelElementHandler, pDevice);
   463 				}
   464 			}
   465 
   466 			CFRelease (usbProperties);
   467 		}
   468 		else
   469 			SDL_SetError ("IORegistryEntryCreateCFProperties failed to create usbProperties.");
   470 
   471 		if (kIOReturnSuccess != IOObjectRelease (parent2))
   472 			SDL_SetError ("IOObjectRelease error with parent2.");
   473 		if (kIOReturnSuccess != IOObjectRelease (parent1))
   474 			SDL_SetError ("IOObjectRelease error with parent1.");
   475 	}
   476 }
   477 
   478 
   479 static recDevice *HIDBuildDevice (io_object_t hidDevice)
   480 {
   481 	recDevice *pDevice = (recDevice *) NewPtrClear (sizeof (recDevice));
   482 	if (pDevice)
   483 	{
   484 		/* get dictionary for HID properties */
   485 		CFMutableDictionaryRef hidProperties = 0;
   486 		kern_return_t result = IORegistryEntryCreateCFProperties (hidDevice, &hidProperties, kCFAllocatorDefault, kNilOptions);
   487 		if ((result == KERN_SUCCESS) && hidProperties)
   488 		{
   489 			/* create device interface */
   490 			result = HIDCreateOpenDeviceInterface (hidDevice, pDevice);
   491 			if (kIOReturnSuccess == result)
   492 			{
   493 				HIDGetDeviceInfo (hidDevice, hidProperties, pDevice); /* hidDevice used to find parents in registry tree */
   494 				HIDGetCollectionElements (hidProperties, pDevice);
   495 			}
   496 			else
   497 			{
   498 				DisposePtr(pDevice);
   499 				pDevice = NULL;
   500 			}
   501 			CFRelease (hidProperties);
   502 		}
   503 		else
   504 		{
   505 			DisposePtr(pDevice);
   506 			pDevice = NULL;
   507 		}
   508 	}
   509 	return pDevice;
   510 }
   511 
   512 /* disposes of the element list associated with a device and the memory associated with the list
   513  */
   514 
   515 static void HIDDisposeElementList (recElement **elementList)
   516 {
   517 	recElement *pElement = *elementList;
   518 	while (pElement)
   519 	{
   520 		recElement *pElementNext = pElement->pNext;
   521 		DisposePtr ((Ptr) pElement);
   522 		pElement = pElementNext;
   523 	}
   524 	*elementList = NULL;
   525 }
   526 
   527 /* disposes of a single device, closing and releaseing interface, freeing memory fro device and elements, setting device pointer to NULL
   528  * all your device no longer belong to us... (i.e., you do not 'own' the device anymore)
   529  */
   530 
   531 static recDevice *HIDDisposeDevice (recDevice **ppDevice)
   532 {
   533 	kern_return_t result = KERN_SUCCESS;
   534 	recDevice *pDeviceNext = NULL;
   535 	if (*ppDevice)
   536 	{
   537 		// save next device prior to disposing of this device
   538 		pDeviceNext = (*ppDevice)->pNext;
   539 		
   540 		/* free element lists */
   541 		HIDDisposeElementList (&(*ppDevice)->firstAxis);
   542 		HIDDisposeElementList (&(*ppDevice)->firstButton);
   543 		HIDDisposeElementList (&(*ppDevice)->firstHat);
   544 		
   545 		result = HIDCloseReleaseInterface (*ppDevice); /* function sanity checks interface value (now application does not own device) */
   546 		if (kIOReturnSuccess != result)
   547 			HIDReportErrorNum ("HIDCloseReleaseInterface failed when trying to dipose device.", result);
   548 		DisposePtr ((Ptr)*ppDevice);
   549 		*ppDevice = NULL;
   550 	}
   551 	return pDeviceNext;
   552 }
   553 
   554 
   555 /* Function to scan the system for joysticks.
   556  * Joystick 0 should be the system default joystick.
   557  * This function should return the number of available joysticks, or -1
   558  * on an unrecoverable fatal error.
   559  */
   560 int SDL_SYS_JoystickInit(void)
   561 {
   562 	IOReturn result = kIOReturnSuccess;
   563 	mach_port_t masterPort = NULL;
   564 	io_iterator_t hidObjectIterator = NULL;
   565 	CFMutableDictionaryRef hidMatchDictionary = NULL;
   566 	recDevice *device, *lastDevice;
   567 	io_object_t ioHIDDeviceObject = NULL;
   568 	UInt32 usagePage = kHIDPage_GenericDesktop;
   569 	UInt32 usage = kHIDUsage_GD_Joystick; /* We probably also should check for gamepads? */
   570 	
   571 	SDL_numjoysticks = 0;
   572 	
   573 	if (NULL != gpDeviceList)
   574 	{
   575 		SDL_SetError("Joystick: Device list already inited.");
   576 		return -1;
   577 	}
   578 	
   579 	result = IOMasterPort (bootstrap_port, &masterPort);
   580 	if (kIOReturnSuccess != result)
   581 	{
   582 		SDL_SetError("Joystick: IOMasterPort error with bootstrap_port.");
   583 		return -1;
   584 	}
   585 
   586 	/* Set up a matching dictionary to search I/O Registry by class name for all HID class devices. */
   587 	hidMatchDictionary = IOServiceMatching (kIOHIDDeviceKey);
   588 	if ((hidMatchDictionary != NULL) && (usagePage) && (usage))
   589 	{
   590 		/* Add key for device type (joystick, in this case) to refine the matching dictionary. */
   591 		CFNumberRef refUsage = NULL, refUsagePage = NULL;
   592 
   593 		refUsage = CFNumberCreate (kCFAllocatorDefault, kCFNumberIntType, &usagePage);
   594 		CFDictionarySetValue (hidMatchDictionary, CFSTR (kIOHIDPrimaryUsageKey), refUsage);
   595 		refUsagePage = CFNumberCreate (kCFAllocatorDefault, kCFNumberIntType, &usage);
   596 		CFDictionarySetValue (hidMatchDictionary, CFSTR (kIOHIDPrimaryUsagePageKey), refUsagePage);
   597 	}
   598 	else
   599 	{
   600 		SDL_SetError("Joystick: Failed to get HID CFMutableDictionaryRef via IOServiceMatching.");
   601 		return -1;
   602 	}
   603 	
   604 	/*/ Now search I/O Registry for matching devices. */
   605 	result = IOServiceGetMatchingServices (masterPort, hidMatchDictionary, &hidObjectIterator);
   606 	/* Check for errors */
   607 	if ((kIOReturnSuccess != result) || (NULL == hidObjectIterator))
   608 	{
   609 		SDL_SetError("Joystick: Couldn't create a HID object iterator.");
   610 		return -1;
   611 	}
   612 	/* IOServiceGetMatchingServices consumes a reference to the dictionary, so we don't need to release the dictionary ref. */
   613 
   614 	/* build flat linked list of devices from device iterator */
   615 
   616 	gpDeviceList = lastDevice = NULL;
   617 	
   618 	while ((ioHIDDeviceObject = IOIteratorNext (hidObjectIterator)))
   619 	{
   620 		/* build a device record */
   621 		device = HIDBuildDevice (ioHIDDeviceObject);
   622 		if (!device)
   623 			continue;
   624 
   625 		/* dump device object, it is no longer needed */
   626 		result = IOObjectRelease (ioHIDDeviceObject);
   627 //		if (KERN_SUCCESS != result)
   628 //			HIDReportErrorNum ("IOObjectRelease error with ioHIDDeviceObject.", result);
   629 		/* Add device to the end of the list */
   630 		if (lastDevice)
   631 			lastDevice->pNext = device;
   632 		else
   633 			gpDeviceList = device;
   634 		lastDevice = device;
   635 	}
   636 	result = IOObjectRelease (hidObjectIterator); /* release the iterator */
   637 
   638 	/* Count the total number of devices we found */
   639 	device = gpDeviceList;
   640 	while (device)
   641 	{
   642 		SDL_numjoysticks++;
   643 		device = device->pNext;
   644 	}
   645 	
   646 	return SDL_numjoysticks;
   647 }
   648 
   649 /* Function to get the device-dependent name of a joystick */
   650 const char *SDL_SYS_JoystickName(int index)
   651 {
   652 	recDevice *device = gpDeviceList;
   653 	
   654 	for (; index > 0; index--)
   655 		device = device->pNext;
   656 
   657 	return device->product;
   658 }
   659 
   660 /* Function to open a joystick for use.
   661  * The joystick to open is specified by the index field of the joystick.
   662  * This should fill the nbuttons and naxes fields of the joystick structure.
   663  * It returns 0, or -1 if there is an error.
   664  */
   665 int SDL_SYS_JoystickOpen(SDL_Joystick *joystick)
   666 {
   667 	recDevice *device = gpDeviceList;
   668 	int index;
   669 	
   670 	for (index = joystick->index; index > 0; index--)
   671 		device = device->pNext;
   672 
   673 	joystick->hwdata = device;
   674 	joystick->name = device->product;
   675 
   676 	joystick->naxes = device->axes;
   677 	joystick->nhats = device->hats;
   678 	joystick->nballs = 0;
   679 	joystick->nbuttons = device->buttons;
   680 
   681 	return 0;
   682 }
   683 
   684 /* Function to update the state of a joystick - called as a device poll.
   685  * This function shouldn't update the joystick structure directly,
   686  * but instead should call SDL_PrivateJoystick*() to deliver events
   687  * and update joystick device state.
   688  */
   689 void SDL_SYS_JoystickUpdate(SDL_Joystick *joystick)
   690 {
   691 	recDevice *device = joystick->hwdata;
   692 	recElement *element;
   693 	SInt32 value;
   694 	int i;
   695 	
   696 	element = device->firstAxis;
   697 	i = 0;
   698 	while (element)
   699 	{
   700 		value = HIDScaledCalibratedValue(device, element, -32768, 32767);
   701 		if ( value != joystick->axes[i] )
   702 			SDL_PrivateJoystickAxis(joystick, i, value);
   703 		element = element->pNext;
   704 		++i;
   705 	}
   706 	
   707 	element = device->firstButton;
   708 	i = 0;
   709 	while (element)
   710 	{
   711 		value = HIDGetElementValue(device, element);
   712 		if ( value != joystick->buttons[i] )
   713 			SDL_PrivateJoystickButton(joystick, i, value);
   714 		element = element->pNext;
   715 		++i;
   716 	}
   717 	
   718 	element = device->firstHat;
   719 	i = 0;
   720 	while (element)
   721 	{
   722 		Uint8 pos;
   723 
   724 		value = HIDGetElementValue(device, element);
   725 		switch(value)
   726 		{
   727 			case 0:
   728 				pos = SDL_HAT_CENTERED;
   729 				break;
   730 			case 1:
   731 				pos = SDL_HAT_UP;
   732 				break;
   733 			case 2:
   734 				pos = SDL_HAT_RIGHTUP;
   735 				break;
   736 			case 3:
   737 				pos = SDL_HAT_RIGHT;
   738 				break;
   739 			case 4:
   740 				pos = SDL_HAT_RIGHTDOWN;
   741 				break;
   742 			case 5:
   743 				pos = SDL_HAT_DOWN;
   744 				break;
   745 			case 6:
   746 				pos = SDL_HAT_LEFTDOWN;
   747 				break;
   748 			case 7:
   749 				pos = SDL_HAT_LEFT;
   750 				break;
   751 			case 8:
   752 				pos = SDL_HAT_LEFTUP;
   753 				break;
   754 		}
   755 		if ( pos != joystick->hats[i] )
   756 			SDL_PrivateJoystickHat(joystick, i, pos);
   757 		element = element->pNext;
   758 		++i;
   759 	}
   760 	
   761 	return;
   762 }
   763 
   764 /* Function to close a joystick after use */
   765 void SDL_SYS_JoystickClose(SDL_Joystick *joystick)
   766 {
   767 	/* Should we do anything here? */
   768 	return;
   769 }
   770 
   771 /* Function to perform any system-specific joystick related cleanup */
   772 void SDL_SYS_JoystickQuit(void)
   773 {
   774 	while (NULL != gpDeviceList)
   775 		gpDeviceList = HIDDisposeDevice (&gpDeviceList);
   776 }