src/joystick/darwin/SDL_sysjoystick.c
author Sam Lantinga <slouken@libsdl.org>
Thu, 13 Apr 2006 13:08:26 +0000
changeset 1621 f12379c41042
parent 1496 405e20dc004c
child 1635 92947e3a18db
permissions -rw-r--r--
Fixes bug #195: The proper name of Apple's operating system is "Mac OS X" not "MacOS X", as can bee seen in many places, for example http://www.apple.com/macosx/). This contrasts the naming of the old operating system, which was called "MacOS" and today is often refered to as "MacOS Classic". The attached patches fixes the misuse of the name "MacOS X" in both the SDL12 and sdlweb CVS modules.

/*
	SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2004 Sam Lantinga

	This library is free software; you can redistribute it and/or
	modify it under the terms of the GNU Library General Public
	License as published by the Free Software Foundation; either
	version 2 of the License, or (at your option) any later version.

	This library is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
	Library General Public License for more details.

	You should have received a copy of the GNU Library General Public
	License along with this library; if not, write to the Free
	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

	Sam Lantinga
	slouken@libsdl.org
*/
#include "SDL_config.h"

/* SDL joystick driver for Darwin / Mac OS X, based on the IOKit HID API */
/* Written 2001 by Max Horn */

#include <unistd.h>
#include <ctype.h>
#include <sysexits.h>
#include <mach/mach.h>
#include <mach/mach_error.h>
#include <IOKit/IOKitLib.h>
#include <IOKit/IOCFPlugIn.h>
#ifdef MACOS_10_0_4
#include <IOKit/hidsystem/IOHIDUsageTables.h>
#else
/* The header was moved here in Mac OS X 10.1 */
#include <Kernel/IOKit/hidsystem/IOHIDUsageTables.h>
#endif
#include <IOKit/hid/IOHIDLib.h>
#include <IOKit/hid/IOHIDKeys.h>
#include <CoreFoundation/CoreFoundation.h>
#include <Carbon/Carbon.h> /* for NewPtrClear, DisposePtr */

#include "SDL_joystick.h"
#include "../SDL_sysjoystick.h"
#include "../SDL_joystick_c.h"

struct recElement
{
	IOHIDElementCookie cookie;				/* unique value which identifies element, will NOT change */
	long min;								/* reported min value possible */
	long max;								/* reported max value possible */
#if 0
	/* TODO: maybe should handle the following stuff somehow? */

	long scaledMin;							/* reported scaled min value possible */
	long scaledMax;							/* reported scaled max value possible */
	long size;								/* size in bits of data return from element */
	Boolean relative;						/* are reports relative to last report (deltas) */
	Boolean wrapping;						/* does element wrap around (one value higher than max is min) */
	Boolean nonLinear;						/* are the values reported non-linear relative to element movement */
	Boolean preferredState;					/* does element have a preferred state (such as a button) */
	Boolean nullState;						/* does element have null state */
#endif /* 0 */

	/* runtime variables used for auto-calibration */
	long minReport;							/* min returned value */
	long maxReport;							/* max returned value */
	
	struct recElement * pNext;				/* next element in list */
};
typedef struct recElement recElement;

struct joystick_hwdata
{
	IOHIDDeviceInterface ** interface;		/* interface to device, NULL = no interface */

	char product[256];							/* name of product */
	long usage;								/* usage page from IOUSBHID Parser.h which defines general usage */
	long usagePage;							/* usage within above page from IOUSBHID Parser.h which defines specific usage */

	long axes;								/* number of axis (calculated, not reported by device) */
	long buttons;							/* number of buttons (calculated, not reported by device) */
	long hats;								/* number of hat switches (calculated, not reported by device) */
	long elements;							/* number of total elements (shouldbe total of above) (calculated, not reported by device) */

	recElement* firstAxis;
	recElement* firstButton;
	recElement* firstHat;

	int removed;
	int uncentered;

	struct joystick_hwdata* pNext;			/* next device */
};
typedef struct joystick_hwdata recDevice;


/* Linked list of all available devices */
static recDevice *gpDeviceList = NULL;


static void HIDReportErrorNum (char * strError, long numError)
{
	SDL_SetError(strError);
}

static void HIDGetCollectionElements (CFMutableDictionaryRef deviceProperties, recDevice *pDevice);

/* returns current value for element, polling element
 * will return 0 on error conditions which should be accounted for by application
 */

static SInt32 HIDGetElementValue (recDevice *pDevice, recElement *pElement)
{
	IOReturn result = kIOReturnSuccess;
	IOHIDEventStruct hidEvent;
	hidEvent.value = 0;
	
	if (NULL != pDevice && NULL != pElement && NULL != pDevice->interface)
	{
		result = (*(pDevice->interface))->getElementValue(pDevice->interface, pElement->cookie, &hidEvent);
		if (kIOReturnSuccess == result)
		{
			/* record min and max for auto calibration */
			if (hidEvent.value < pElement->minReport)
				pElement->minReport = hidEvent.value;
			if (hidEvent.value > pElement->maxReport)
				pElement->maxReport = hidEvent.value;
		}
	}

	/* auto user scale */
	return hidEvent.value;
}

static SInt32 HIDScaledCalibratedValue (recDevice *pDevice, recElement *pElement, long min, long max)
{
	float deviceScale = max - min;
	float readScale = pElement->maxReport - pElement->minReport;
	SInt32 value = HIDGetElementValue(pDevice, pElement);
	if (readScale == 0)
		return value; /* no scaling at all */
	else
		return ((value - pElement->minReport) * deviceScale / readScale) + min;
}


static void HIDRemovalCallback(void * target,
                               IOReturn result,
                               void * refcon,
                               void * sender)
{
	recDevice *device = (recDevice *) refcon;
	device->removed = 1;
	device->uncentered = 1;
}



/* Create and open an interface to device, required prior to extracting values or building queues.
 * Note: appliction now owns the device and must close and release it prior to exiting
 */

static IOReturn HIDCreateOpenDeviceInterface (io_object_t hidDevice, recDevice *pDevice)
{
	IOReturn result = kIOReturnSuccess;
	HRESULT plugInResult = S_OK;
	SInt32 score = 0;
	IOCFPlugInInterface ** ppPlugInInterface = NULL;
	
	if (NULL == pDevice->interface)
	{
		result = IOCreatePlugInInterfaceForService (hidDevice, kIOHIDDeviceUserClientTypeID,
													kIOCFPlugInInterfaceID, &ppPlugInInterface, &score);
		if (kIOReturnSuccess == result)
		{
			/* Call a method of the intermediate plug-in to create the device interface */
			plugInResult = (*ppPlugInInterface)->QueryInterface (ppPlugInInterface,
								CFUUIDGetUUIDBytes (kIOHIDDeviceInterfaceID), (void *) &(pDevice->interface));
			if (S_OK != plugInResult)
				HIDReportErrorNum ("CouldnŐt query HID class device interface from plugInInterface", plugInResult);
			(*ppPlugInInterface)->Release (ppPlugInInterface);
		}
		else
			HIDReportErrorNum ("Failed to create **plugInInterface via IOCreatePlugInInterfaceForService.", result);
	}
	if (NULL != pDevice->interface)
	{
		result = (*(pDevice->interface))->open (pDevice->interface, 0);
		if (kIOReturnSuccess != result)
			HIDReportErrorNum ("Failed to open pDevice->interface via open.", result);
		else
			(*(pDevice->interface))->setRemovalCallback (pDevice->interface, HIDRemovalCallback, pDevice, pDevice);

	}
	return result;
}

/* Closes and releases interface to device, should be done prior to exting application
 * Note: will have no affect if device or interface do not exist
 * application will "own" the device if interface is not closed
 * (device may have to be plug and re-plugged in different location to get it working again without a restart)
 */

static IOReturn HIDCloseReleaseInterface (recDevice *pDevice)
{
	IOReturn result = kIOReturnSuccess;
	
	if ((NULL != pDevice) && (NULL != pDevice->interface))
	{
		/* close the interface */
		result = (*(pDevice->interface))->close (pDevice->interface);
		if (kIOReturnNotOpen == result)
		{
			/* do nothing as device was not opened, thus can't be closed */
		}
		else if (kIOReturnSuccess != result)
			HIDReportErrorNum ("Failed to close IOHIDDeviceInterface.", result);
		/* release the interface */
		result = (*(pDevice->interface))->Release (pDevice->interface);
		if (kIOReturnSuccess != result)
			HIDReportErrorNum ("Failed to release IOHIDDeviceInterface.", result);
		pDevice->interface = NULL;
	}	
	return result;
}

/* extracts actual specific element information from each element CF dictionary entry */

static void HIDGetElementInfo (CFTypeRef refElement, recElement *pElement)
{
	long number;
	CFTypeRef refType;

	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementCookieKey));
	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
		pElement->cookie = (IOHIDElementCookie) number;
	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementMinKey));
	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
		pElement->min = number;
		pElement->maxReport = pElement->min;
	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementMaxKey));
	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
		pElement->max = number;
		pElement->minReport = pElement->max;
/*
	TODO: maybe should handle the following stuff somehow?

	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementScaledMinKey));
	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
		pElement->scaledMin = number;
	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementScaledMaxKey));
	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
		pElement->scaledMax = number;
	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementSizeKey));
	if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
		pElement->size = number;
	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementIsRelativeKey));
	if (refType)
		pElement->relative = CFBooleanGetValue (refType);
	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementIsWrappingKey));
	if (refType)
		pElement->wrapping = CFBooleanGetValue (refType);
	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementIsNonLinearKey));
	if (refType)
		pElement->nonLinear = CFBooleanGetValue (refType);
	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementHasPreferedStateKey));
	if (refType)
		pElement->preferredState = CFBooleanGetValue (refType);
	refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementHasNullStateKey));
	if (refType)
		pElement->nullState = CFBooleanGetValue (refType);
*/
}			

/* examines CF dictionary vlaue in device element hierarchy to determine if it is element of interest or a collection of more elements
 * if element of interest allocate storage, add to list and retrieve element specific info
 * if collection then pass on to deconstruction collection into additional individual elements
 */

static void HIDAddElement (CFTypeRef refElement, recDevice* pDevice)
{
	recElement* element = NULL;
	recElement** headElement = NULL;
	long elementType, usagePage, usage;
	CFTypeRef refElementType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementTypeKey));
	CFTypeRef refUsagePage = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementUsagePageKey));
	CFTypeRef refUsage = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementUsageKey));


	if ((refElementType) && (CFNumberGetValue (refElementType, kCFNumberLongType, &elementType)))
	{
		/* look at types of interest */
		if ((elementType == kIOHIDElementTypeInput_Misc) || (elementType == kIOHIDElementTypeInput_Button) ||
			(elementType == kIOHIDElementTypeInput_Axis))
		{
			if (refUsagePage && CFNumberGetValue (refUsagePage, kCFNumberLongType, &usagePage) &&
				refUsage && CFNumberGetValue (refUsage, kCFNumberLongType, &usage))
			{
				switch (usagePage) /* only interested in kHIDPage_GenericDesktop and kHIDPage_Button */
				{
					case kHIDPage_GenericDesktop:
						{
							switch (usage) /* look at usage to determine function */
							{
								case kHIDUsage_GD_X:
								case kHIDUsage_GD_Y:
								case kHIDUsage_GD_Z:
								case kHIDUsage_GD_Rx:
								case kHIDUsage_GD_Ry:
								case kHIDUsage_GD_Rz:
								case kHIDUsage_GD_Slider:
								case kHIDUsage_GD_Dial:
								case kHIDUsage_GD_Wheel:
									element = (recElement *) NewPtrClear (sizeof (recElement));
									if (element)
									{
										pDevice->axes++;
										headElement = &(pDevice->firstAxis);
									}
								break;
								case kHIDUsage_GD_Hatswitch:
									element = (recElement *) NewPtrClear (sizeof (recElement));
									if (element)
									{
										pDevice->hats++;
										headElement = &(pDevice->firstHat);
									}
								break;
							}							
						}
						break;
					case kHIDPage_Button:
						element = (recElement *) NewPtrClear (sizeof (recElement));
						if (element)
						{
							pDevice->buttons++;
							headElement = &(pDevice->firstButton);
						}
						break;
					default:
						break;
				}
			}
		}
		else if (kIOHIDElementTypeCollection == elementType)
			HIDGetCollectionElements ((CFMutableDictionaryRef) refElement, pDevice);
	}

	if (element && headElement) /* add to list */
	{
		pDevice->elements++;
		if (NULL == *headElement)
			*headElement = element;
		else
		{
			recElement *elementPrevious, *elementCurrent;
			elementCurrent = *headElement;
			while (elementCurrent)
			{
				elementPrevious = elementCurrent;
				elementCurrent = elementPrevious->pNext;
			}
			elementPrevious->pNext = element;
		}
		element->pNext = NULL;
		HIDGetElementInfo (refElement, element);
	}
}

/* collects information from each array member in device element list (each array memeber = element) */

static void HIDGetElementsCFArrayHandler (const void * value, void * parameter)
{
	if (CFGetTypeID (value) == CFDictionaryGetTypeID ())
		HIDAddElement ((CFTypeRef) value, (recDevice *) parameter);
}

/* handles retrieval of element information from arrays of elements in device IO registry information */

static void HIDGetElements (CFTypeRef refElementCurrent, recDevice *pDevice)
{
	CFTypeID type = CFGetTypeID (refElementCurrent);
	if (type == CFArrayGetTypeID()) /* if element is an array */
	{
		CFRange range = {0, CFArrayGetCount (refElementCurrent)};
		/* CountElementsCFArrayHandler called for each array member */
		CFArrayApplyFunction (refElementCurrent, range, HIDGetElementsCFArrayHandler, pDevice);
	}
}			

/* handles extracting element information from element collection CF types
 * used from top level element decoding and hierarchy deconstruction to flatten device element list
 */

static void HIDGetCollectionElements (CFMutableDictionaryRef deviceProperties, recDevice *pDevice)
{
	CFTypeRef refElementTop = CFDictionaryGetValue (deviceProperties, CFSTR(kIOHIDElementKey));
	if (refElementTop)
		HIDGetElements (refElementTop, pDevice);
}

/* use top level element usage page and usage to discern device usage page and usage setting appropriate vlaues in device record */

static void HIDTopLevelElementHandler (const void * value, void * parameter)
{
	CFTypeRef refCF = 0;
	if (CFGetTypeID (value) != CFDictionaryGetTypeID ())
		return;
	refCF = CFDictionaryGetValue (value, CFSTR(kIOHIDElementUsagePageKey));
	if (!CFNumberGetValue (refCF, kCFNumberLongType, &((recDevice *) parameter)->usagePage))
		SDL_SetError ("CFNumberGetValue error retrieving pDevice->usagePage.");
	refCF = CFDictionaryGetValue (value, CFSTR(kIOHIDElementUsageKey));
	if (!CFNumberGetValue (refCF, kCFNumberLongType, &((recDevice *) parameter)->usage))
		SDL_SetError ("CFNumberGetValue error retrieving pDevice->usage.");
}

/* extracts device info from CF dictionary records in IO registry */

static void HIDGetDeviceInfo (io_object_t hidDevice, CFMutableDictionaryRef hidProperties, recDevice *pDevice)
{
	CFMutableDictionaryRef usbProperties = 0;
	io_registry_entry_t parent1, parent2;
	
	/* Mac OS X currently is not mirroring all USB properties to HID page so need to look at USB device page also
	 * get dictionary for usb properties: step up two levels and get CF dictionary for USB properties
	 */
	if ((KERN_SUCCESS == IORegistryEntryGetParentEntry (hidDevice, kIOServicePlane, &parent1)) &&
		(KERN_SUCCESS == IORegistryEntryGetParentEntry (parent1, kIOServicePlane, &parent2)) &&
		(KERN_SUCCESS == IORegistryEntryCreateCFProperties (parent2, &usbProperties, kCFAllocatorDefault, kNilOptions)))
	{
		if (usbProperties)
		{
			CFTypeRef refCF = 0;
			/* get device info
			 * try hid dictionary first, if fail then go to usb dictionary
			 */
			
			
			/* get product name */
			refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDProductKey));
			if (!refCF)
				refCF = CFDictionaryGetValue (usbProperties, CFSTR("USB Product Name"));
			if (refCF)
			{
				if (!CFStringGetCString (refCF, pDevice->product, 256, CFStringGetSystemEncoding ()))
					SDL_SetError ("CFStringGetCString error retrieving pDevice->product.");
			}
			
			/* get usage page and usage */
			refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDPrimaryUsagePageKey));
			if (refCF)
			{
				if (!CFNumberGetValue (refCF, kCFNumberLongType, &pDevice->usagePage))
					SDL_SetError ("CFNumberGetValue error retrieving pDevice->usagePage.");
				refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDPrimaryUsageKey));
				if (refCF)
					if (!CFNumberGetValue (refCF, kCFNumberLongType, &pDevice->usage))
						SDL_SetError ("CFNumberGetValue error retrieving pDevice->usage.");
			}

			if (NULL == refCF) /* get top level element HID usage page or usage */
			{
				/* use top level element instead */
				CFTypeRef refCFTopElement = 0;
				refCFTopElement = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDElementKey));
				{
					/* refCFTopElement points to an array of element dictionaries */
					CFRange range = {0, CFArrayGetCount (refCFTopElement)};
					CFArrayApplyFunction (refCFTopElement, range, HIDTopLevelElementHandler, pDevice);
				}
			}

			CFRelease (usbProperties);
		}
		else
			SDL_SetError ("IORegistryEntryCreateCFProperties failed to create usbProperties.");

		if (kIOReturnSuccess != IOObjectRelease (parent2))
			SDL_SetError ("IOObjectRelease error with parent2.");
		if (kIOReturnSuccess != IOObjectRelease (parent1))
			SDL_SetError ("IOObjectRelease error with parent1.");
	}
}


static recDevice *HIDBuildDevice (io_object_t hidDevice)
{
	recDevice *pDevice = (recDevice *) NewPtrClear (sizeof (recDevice));
	if (pDevice)
	{
		/* get dictionary for HID properties */
		CFMutableDictionaryRef hidProperties = 0;
		kern_return_t result = IORegistryEntryCreateCFProperties (hidDevice, &hidProperties, kCFAllocatorDefault, kNilOptions);
		if ((result == KERN_SUCCESS) && hidProperties)
		{
			/* create device interface */
			result = HIDCreateOpenDeviceInterface (hidDevice, pDevice);
			if (kIOReturnSuccess == result)
			{
				HIDGetDeviceInfo (hidDevice, hidProperties, pDevice); /* hidDevice used to find parents in registry tree */
				HIDGetCollectionElements (hidProperties, pDevice);
			}
			else
			{
				DisposePtr((Ptr)pDevice);
				pDevice = NULL;
			}
			CFRelease (hidProperties);
		}
		else
		{
			DisposePtr((Ptr)pDevice);
			pDevice = NULL;
		}
	}
	return pDevice;
}

/* disposes of the element list associated with a device and the memory associated with the list
 */

static void HIDDisposeElementList (recElement **elementList)
{
	recElement *pElement = *elementList;
	while (pElement)
	{
		recElement *pElementNext = pElement->pNext;
		DisposePtr ((Ptr) pElement);
		pElement = pElementNext;
	}
	*elementList = NULL;
}

/* disposes of a single device, closing and releaseing interface, freeing memory fro device and elements, setting device pointer to NULL
 * all your device no longer belong to us... (i.e., you do not 'own' the device anymore)
 */

static recDevice *HIDDisposeDevice (recDevice **ppDevice)
{
	kern_return_t result = KERN_SUCCESS;
	recDevice *pDeviceNext = NULL;
	if (*ppDevice)
	{
		/* save next device prior to disposing of this device */
		pDeviceNext = (*ppDevice)->pNext;
		
		/* free element lists */
		HIDDisposeElementList (&(*ppDevice)->firstAxis);
		HIDDisposeElementList (&(*ppDevice)->firstButton);
		HIDDisposeElementList (&(*ppDevice)->firstHat);
		
		result = HIDCloseReleaseInterface (*ppDevice); /* function sanity checks interface value (now application does not own device) */
		if (kIOReturnSuccess != result)
			HIDReportErrorNum ("HIDCloseReleaseInterface failed when trying to dipose device.", result);
		DisposePtr ((Ptr)*ppDevice);
		*ppDevice = NULL;
	}
	return pDeviceNext;
}


/* Function to scan the system for joysticks.
 * Joystick 0 should be the system default joystick.
 * This function should return the number of available joysticks, or -1
 * on an unrecoverable fatal error.
 */
int SDL_SYS_JoystickInit(void)
{
	IOReturn result = kIOReturnSuccess;
	mach_port_t masterPort = 0;
	io_iterator_t hidObjectIterator = 0;
	CFMutableDictionaryRef hidMatchDictionary = NULL;
	recDevice *device, *lastDevice;
	io_object_t ioHIDDeviceObject = 0;
	
	SDL_numjoysticks = 0;
	
	if (gpDeviceList)
	{
		SDL_SetError("Joystick: Device list already inited.");
		return -1;
	}
	
	result = IOMasterPort (bootstrap_port, &masterPort);
	if (kIOReturnSuccess != result)
	{
		SDL_SetError("Joystick: IOMasterPort error with bootstrap_port.");
		return -1;
	}

	/* Set up a matching dictionary to search I/O Registry by class name for all HID class devices. */
	hidMatchDictionary = IOServiceMatching (kIOHIDDeviceKey);
	if (hidMatchDictionary)
	{
		/* Add key for device type (joystick, in this case) to refine the matching dictionary. */
		
		/* NOTE: we now perform this filtering later
		UInt32 usagePage = kHIDPage_GenericDesktop;
		UInt32 usage = kHIDUsage_GD_Joystick;
		CFNumberRef refUsage = NULL, refUsagePage = NULL;

		refUsage = CFNumberCreate (kCFAllocatorDefault, kCFNumberIntType, &usage);
		CFDictionarySetValue (hidMatchDictionary, CFSTR (kIOHIDPrimaryUsageKey), refUsage);
		refUsagePage = CFNumberCreate (kCFAllocatorDefault, kCFNumberIntType, &usagePage);
		CFDictionarySetValue (hidMatchDictionary, CFSTR (kIOHIDPrimaryUsagePageKey), refUsagePage);
		*/
	}
	else
	{
		SDL_SetError("Joystick: Failed to get HID CFMutableDictionaryRef via IOServiceMatching.");
		return -1;
	}
	
	/*/ Now search I/O Registry for matching devices. */
	result = IOServiceGetMatchingServices (masterPort, hidMatchDictionary, &hidObjectIterator);
	/* Check for errors */
	if (kIOReturnSuccess != result)
	{
		SDL_SetError("Joystick: Couldn't create a HID object iterator.");
		return -1;
	}
	if (!hidObjectIterator) /* there are no joysticks */
	{
		gpDeviceList = NULL;
		SDL_numjoysticks = 0;
		return 0;
	}
	/* IOServiceGetMatchingServices consumes a reference to the dictionary, so we don't need to release the dictionary ref. */

	/* build flat linked list of devices from device iterator */

	gpDeviceList = lastDevice = NULL;
	
	while ((ioHIDDeviceObject = IOIteratorNext (hidObjectIterator)))
	{
		/* build a device record */
		device = HIDBuildDevice (ioHIDDeviceObject);
		if (!device)
			continue;

		/* dump device object, it is no longer needed */
		result = IOObjectRelease (ioHIDDeviceObject);
/*		if (KERN_SUCCESS != result)
			HIDReportErrorNum ("IOObjectRelease error with ioHIDDeviceObject.", result);
*/

		/* Filter device list to non-keyboard/mouse stuff */ 
		if ( (device->usagePage != kHIDPage_GenericDesktop) ||
		     ((device->usage != kHIDUsage_GD_Joystick &&
		      device->usage != kHIDUsage_GD_GamePad)) ) {

			/* release memory for the device */
			HIDDisposeDevice (&device);
			DisposePtr((Ptr)device);
			continue;
		}
		
		/* Add device to the end of the list */
		if (lastDevice)
			lastDevice->pNext = device;
		else
			gpDeviceList = device;
		lastDevice = device;
	}
	result = IOObjectRelease (hidObjectIterator); /* release the iterator */

	/* Count the total number of devices we found */
	device = gpDeviceList;
	while (device)
	{
		SDL_numjoysticks++;
		device = device->pNext;
	}
	
	return SDL_numjoysticks;
}

/* Function to get the device-dependent name of a joystick */
const char *SDL_SYS_JoystickName(int index)
{
	recDevice *device = gpDeviceList;
	
	for (; index > 0; index--)
		device = device->pNext;

	return device->product;
}

/* Function to open a joystick for use.
 * The joystick to open is specified by the index field of the joystick.
 * This should fill the nbuttons and naxes fields of the joystick structure.
 * It returns 0, or -1 if there is an error.
 */
int SDL_SYS_JoystickOpen(SDL_Joystick *joystick)
{
	recDevice *device = gpDeviceList;
	int index;
	
	for (index = joystick->index; index > 0; index--)
		device = device->pNext;

	joystick->hwdata = device;
	joystick->name = device->product;

	joystick->naxes = device->axes;
	joystick->nhats = device->hats;
	joystick->nballs = 0;
	joystick->nbuttons = device->buttons;

	return 0;
}

/* 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.
 */
void SDL_SYS_JoystickUpdate(SDL_Joystick *joystick)
{
	recDevice *device = joystick->hwdata;
	recElement *element;
	SInt32 value;
	int i;

	if (device->removed)  /* device was unplugged; ignore it. */
	{
		if (device->uncentered)
		{
			device->uncentered = 0;

			/* Tell the app that everything is centered/unpressed... */
			for (i = 0; i < device->axes; i++)
				SDL_PrivateJoystickAxis(joystick, i, 0);

			for (i = 0; i < device->buttons; i++)
				SDL_PrivateJoystickButton(joystick, i, 0);

			for (i = 0; i < device->hats; i++)
				SDL_PrivateJoystickHat(joystick, i, SDL_HAT_CENTERED);
		}

		return;
	}

	element = device->firstAxis;
	i = 0;
	while (element)
	{
		value = HIDScaledCalibratedValue(device, element, -32768, 32767);
		if ( value != joystick->axes[i] )
			SDL_PrivateJoystickAxis(joystick, i, value);
		element = element->pNext;
		++i;
	}
	
	element = device->firstButton;
	i = 0;
	while (element)
	{
		value = HIDGetElementValue(device, element);
        if (value > 1)  /* handle pressure-sensitive buttons */
            value = 1;
		if ( value != joystick->buttons[i] )
			SDL_PrivateJoystickButton(joystick, i, value);
		element = element->pNext;
		++i;
	}
	    
	element = device->firstHat;
	i = 0;
	while (element)
	{
		Uint8 pos = 0;

		value = HIDGetElementValue(device, element);
		if (element->max == 3) /* 4 position hatswitch - scale up value */
			value *= 2;
		else if (element->max != 7) /* Neither a 4 nor 8 positions - fall back to default position (centered) */
			value = -1;
		switch(value)
		{
			case 0:
				pos = SDL_HAT_UP;
				break;
			case 1:
				pos = SDL_HAT_RIGHTUP;
				break;
			case 2:
				pos = SDL_HAT_RIGHT;
				break;
			case 3:
				pos = SDL_HAT_RIGHTDOWN;
				break;
			case 4:
				pos = SDL_HAT_DOWN;
				break;
			case 5:
				pos = SDL_HAT_LEFTDOWN;
				break;
			case 6:
				pos = SDL_HAT_LEFT;
				break;
			case 7:
				pos = SDL_HAT_LEFTUP;
				break;
			default:
				/* Every other value is mapped to center. We do that because some
				 * joysticks use 8 and some 15 for this value, and apparently
				 * there are even more variants out there - so we try to be generous.
				 */
				pos = SDL_HAT_CENTERED;
				break;
		}
		if ( pos != joystick->hats[i] )
			SDL_PrivateJoystickHat(joystick, i, pos);
		element = element->pNext;
		++i;
	}
	
	return;
}

/* Function to close a joystick after use */
void SDL_SYS_JoystickClose(SDL_Joystick *joystick)
{
	/* Should we do anything here? */
	return;
}

/* Function to perform any system-specific joystick related cleanup */
void SDL_SYS_JoystickQuit(void)
{
	while (NULL != gpDeviceList)
		gpDeviceList = HIDDisposeDevice (&gpDeviceList);
}