/*
Copyright (c) 2003-2007 Ryan C. Gordon and others.

http://icculus.org/manymouse/

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.

    Ryan C. Gordon <icculus@icculus.org>
*/

//Support for MacOS X via the HID Manager APIs.

#include "mm.h"

#if ( (defined(__MACH__)) && (defined(__APPLE__)) )

/*
 * This source is almost entirely lifted from Apple's HID Utilities
 *  example source code, written by George Warner:
 *
 * http://developer.apple.com/samplecode/HID_Utilities_Source/HID_Utilities_Source.html
 *
 * The source license to HID Utilities allows this sort of blatant stealing.
 *
 * Patches to HID Utilities have comments like "ryan added this", otherwise,
 *  I just tried to cut down that package to the smallest set of functions
 *  I needed.
 *
 * Scroll down for "-- END HID UTILITIES --" to see the ManyMouse glue code.
 */

#include <Carbon/Carbon.h>

#include <IOKit/IOTypes.h>
// 10.0.x
//#include <IOKit/IOUSBHIDParser.h>
// 10.1.x
#include <IOKit/hid/IOHIDUsageTables.h>
#include <IOKit/hid/IOHIDLib.h>
#include <IOKit/IOCFPlugIn.h>
#include <IOKit/IOKitLib.h>
#include <IOKit/IOMessage.h>

#define USE_NOTIFICATIONS 1

#define HIDREPORTERRORNUM(s,n)  do {} while (false)
#define HIDREPORTERROR(s)   do {} while (false)

typedef enum HIDElementTypeMask
{
  kHIDElementTypeInput        = 1 << 1,
  kHIDElementTypeOutput             = 1 << 2,
  kHIDElementTypeFeature            = 1 << 3,
  kHIDElementTypeCollection         = 1 << 4,
  kHIDElementTypeIO         = kHIDElementTypeInput | kHIDElementTypeOutput | kHIDElementTypeFeature,
  kHIDElementTypeAll          = kHIDElementTypeIO | kHIDElementTypeCollection
}HIDElementTypeMask;

enum
{
    kDefaultUserMin = 0,          // default user min and max used for scaling
    kDefaultUserMax = 255
};

enum
{
    kDeviceQueueSize = 50 // this is wired kernel memory so should be set to as small as possible
              // but should account for the maximum possible events in the queue
              // USB updates will likely occur at 100 Hz so one must account for this rate of
              // if states change quickly (updates are only posted on state changes)
};

struct recElement
{
    unsigned long type;           // the type defined by IOHIDElementType in IOHIDKeys.h
    long usagePage;             // usage page from IOUSBHIDParser.h which defines general usage
    long usage;               // usage within above page from IOUSBHIDParser.h which defines specific usage
    void * cookie;              // unique value (within device of specific vendorID and productID) which identifies element, will NOT change
    long min;               // reported min value possible
    long max;               // reported max value possible
    long scaledMin;             // reported scaled min value possible
    long scaledMax;             // reported scaled max value possible
    long size;                // size in bits of data return from element
    unsigned char relative;         // are reports relative to last report (deltas)
    unsigned char wrapping;         // does element wrap around (one value higher than max is min)
    unsigned char nonLinear;        // are the values reported non-linear relative to element movement
    unsigned char preferredState;     // does element have a preferred state (such as a button)
    unsigned char nullState;        // does element have null state
    long units;               // units value is reported in (not used very often)
    long unitExp;             // exponent for units (also not used very often)
    char name[256];             // name of element (c string)

// runtime variables
    long calMin;              // min returned value
    long calMax;              // max returned value (calibrate call)
    long userMin;               // user set value to scale to (scale call)
    long userMax;

  struct recElement * pPrevious;      // previous element (NULL at list head)
    struct recElement * pChild;       // next child (only of collections)
    struct recElement * pSibling;     // next sibling (for elements and collections)

  long depth;
};
typedef struct recElement recElement;
typedef recElement* pRecElement;

// ryan added this.
typedef enum
{
    DISCONNECT_CONNECTED,
    DISCONNECT_TELLUSER,
    DISCONNECT_COMPLETE
} DisconnectState;

struct recDevice
{
    void * interface;           // interface to device, NULL = no interface
    void * queue;             // device queue, NULL = no queue
  void * queueRunLoopSource;        // device queue run loop source, NULL == no source
  void * transaction;           // output transaction interface, NULL == no interface
  void * notification;          // notifications
    char transport[256];          // device transport (c string)
    long vendorID;              // id for device vendor, unique across all devices
    long productID;             // id for particular product, unique across all of a vendors devices
    long version;             // version of product
    char manufacturer[256];         // name of manufacturer
    char product[256];            // name of product
    char serial[256];           // serial number of specific product, can be assumed unique across specific product or specific vendor (not used often)
    long locID;               // long representing location in USB (or other I/O) chain which device is pluged into, can identify specific device on machine
    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 totalElements;           // number of total elements (should be total of all elements on device including collections) (calculated, not reported by device)
  long features;              // number of elements of type kIOHIDElementTypeFeature
  long inputs;              // number of elements of type kIOHIDElementTypeInput_Misc or kIOHIDElementTypeInput_Button or kIOHIDElementTypeInput_Axis or kIOHIDElementTypeInput_ScanCodes
  long outputs;             // number of elements of type kIOHIDElementTypeOutput
  long collections;           // number of elements of type kIOHIDElementTypeCollection
    long axis;                // 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 sliders;             // number of sliders (calculated, not reported by device)
    long dials;               // number of dials (calculated, not reported by device)
    long wheels;              // number of wheels (calculated, not reported by device)
    recElement* pListElements;        // head of linked list of elements
    DisconnectState disconnect; // (ryan added this.)
    AbsoluteTime lastScrollTime;  // (ryan added this.)
    struct recDevice* pNext;        // next device
};
typedef struct recDevice recDevice;
typedef recDevice* pRecDevice;


#if USE_NOTIFICATIONS
static IONotificationPortRef  gNotifyPort;
static io_iterator_t    gAddedIter;
static CFRunLoopRef   gRunLoop;
#endif USE_NOTIFICATIONS

// for element retrieval
static pRecDevice gCurrentGetDevice = NULL;
static Boolean gAddAsChild = false;
static int gDepth = false;

static pRecDevice gpDeviceList = NULL;
static UInt32 gNumDevices = 0;

static Boolean HIDIsValidDevice(const pRecDevice pSearchDevice);
static pRecElement HIDGetFirstDeviceElement (pRecDevice pDevice, HIDElementTypeMask typeMask);
static pRecElement HIDGetNextDeviceElement (pRecElement pElement, HIDElementTypeMask typeMask);
static pRecDevice HIDGetFirstDevice (void);
static pRecDevice HIDGetNextDevice (pRecDevice pDevice);
static void HIDReleaseDeviceList (void);
static unsigned long  HIDDequeueDevice (pRecDevice pDevice);
static void hid_GetElements (CFTypeRef refElementCurrent, pRecElement *ppCurrentElement);


static void HIDReportError(const char *err) {}
static void HIDReportErrorNum(const char *err, int num) {}


static void hid_GetCollectionElements (CFMutableDictionaryRef deviceProperties, pRecElement *ppCurrentCollection)
{
    CFTypeRef refElementTop = CFDictionaryGetValue (deviceProperties, CFSTR(kIOHIDElementKey));
    if (refElementTop)
        hid_GetElements (refElementTop, ppCurrentCollection);
    else
        HIDReportError ("hid_GetCollectionElements: CFDictionaryGetValue error when creating CFTypeRef for kIOHIDElementKey.");
}


// extracts actual specific element information from each element CF dictionary entry
static void hid_GetElementInfo (CFTypeRef refElement, pRecElement pElement)
{
  long number;
  CFTypeRef refType;
  // type, usagePage, usage already stored
  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementCookieKey));
  if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
    pElement->cookie = (IOHIDElementCookie) number;
  else
    pElement->cookie = (IOHIDElementCookie) 0;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementMinKey));
  if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
    pElement->min = number;
  else
    pElement->min = 0;

  pElement->calMax = pElement->min;
  pElement->userMin = kDefaultUserMin;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementMaxKey));
  if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
    pElement->max = number;
  else
    pElement->max = 0;

  pElement->calMin = pElement->max;
  pElement->userMax = kDefaultUserMax;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementScaledMinKey));
  if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
    pElement->scaledMin = number;
  else
    pElement->scaledMin = 0;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementScaledMaxKey));
  if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
    pElement->scaledMax = number;
  else
    pElement->scaledMax = 0;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementSizeKey));
  if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
    pElement->size = number;
  else
    pElement->size = 0;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementIsRelativeKey));
  if (refType)
    pElement->relative = CFBooleanGetValue (refType);
  else
    pElement->relative = 0;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementIsWrappingKey));
  if (refType)
    pElement->wrapping = CFBooleanGetValue (refType);
  else
    pElement->wrapping = false;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementIsNonLinearKey));
  if (refType)
    pElement->nonLinear = CFBooleanGetValue (refType);
  else
    pElement->wrapping = false;

#ifdef kIOHIDElementHasPreferredStateKey
  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementHasPreferredStateKey));
#else // Mac OS X 10.0 has spelling error
  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementHasPreferedStateKey));
#endif
  if (refType)
    pElement->preferredState = CFBooleanGetValue (refType);
  else
    pElement->preferredState = false;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementHasNullStateKey));
  if (refType)
    pElement->nullState = CFBooleanGetValue (refType);
  else
    pElement->nullState = false;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementUnitKey));
  if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
    pElement->units = number;
  else
    pElement->units = 0;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementUnitExponentKey));
  if (refType && CFNumberGetValue (refType, kCFNumberLongType, &number))
    pElement->unitExp = number;
  else
    pElement->unitExp = 0;

  refType = CFDictionaryGetValue (refElement, CFSTR(kIOHIDElementNameKey));
  if (refType)
    if (!CFStringGetCString (refType, pElement->name, 256, CFStringGetSystemEncoding ()))
      HIDReportError ("CFStringGetCString error retrieving pElement->name.");

    #if 0
  if (!*pElement->name)
  {
    // set name from vendor id, product id & usage info look up
    if (!HIDGetElementNameFromVendorProductUsage (gCurrentGetDevice->vendorID, gCurrentGetDevice->productID, pElement->usagePage, pElement->usage, pElement->name))
    {
      // set name from vendor id/product id look up
      HIDGetElementNameFromVendorProductCookie (gCurrentGetDevice->vendorID, gCurrentGetDevice->productID, (long) pElement->cookie, pElement->name);
      if (!*pElement->name) { // if no name
        HIDGetUsageName (pElement->usagePage, pElement->usage, pElement->name);
        if (!*pElement->name) // if not usage
          sprintf (pElement->name, "Element");
      }
    }
  }
    #endif
}


static void hid_AddElement (CFTypeRef refElement, pRecElement * ppElementCurrent)
{
  pRecDevice pDevice = gCurrentGetDevice;
    pRecElement pElement = 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);
  if (refUsagePage)
    CFNumberGetValue (refUsagePage, kCFNumberLongType, &usagePage);
  if (refUsage)
    CFNumberGetValue (refUsage, kCFNumberLongType, &usage);

  if (NULL == pDevice)
    return;

    if (elementType)
    {
        // look at types of interest
        if (elementType != kIOHIDElementTypeCollection)
    {
            if (usagePage && usage) // if valid usage and page
      {
        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:
                pElement = (pRecElement) malloc (sizeof (recElement));
                if (pElement) pDevice->axis++;
                  break;
              case kHIDUsage_GD_Slider:
                pElement = (pRecElement) malloc (sizeof (recElement));
                if (pElement) pDevice->sliders++;
                  break;
              case kHIDUsage_GD_Dial:
                pElement = (pRecElement) malloc (sizeof (recElement));
                if (pElement) pDevice->dials++;
                  break;
              case kHIDUsage_GD_Wheel:
                pElement = (pRecElement) malloc (sizeof (recElement));
                if (pElement) pDevice->wheels++;
                  break;
              case kHIDUsage_GD_Hatswitch:
                pElement = (pRecElement) malloc (sizeof (recElement));
                if (pElement) pDevice->hats++;
                  break;
              default:
                pElement = (pRecElement) malloc (sizeof (recElement));
                break;
            }
          }
            break;
          case kHIDPage_Button:
            pElement = (pRecElement) malloc (sizeof (recElement));
            if (pElement) pDevice->buttons++;
              break;
          default:
            // just add a generic element
            pElement = (pRecElement) malloc (sizeof (recElement));
            break;
        }
      }
#if 0
            else
                HIDReportError ("CFNumberGetValue error when getting value for refUsage or refUsagePage.");
#endif 0
        }
        else // collection
      pElement = (pRecElement) malloc (sizeof (recElement));
    }
    else
        HIDReportError ("CFNumberGetValue error when getting value for refElementType.");

    if (pElement) // add to list
    {
    // this code builds a binary tree based on the collection hierarchy of inherent in the device element layout
    // it preserves the structure of the lements as collections have children and elements are siblings to each other

    // clear record
    bzero(pElement,sizeof(recElement));

    // get element info
        pElement->type = elementType;
        pElement->usagePage = usagePage;
        pElement->usage = usage;
        pElement->depth = 0;    // assume root object
        hid_GetElementInfo (refElement, pElement);

    // count elements
    pDevice->totalElements++;

    switch (pElement->type)
    {
      case kIOHIDElementTypeInput_Misc:
      case kIOHIDElementTypeInput_Button:
      case kIOHIDElementTypeInput_Axis:
      case kIOHIDElementTypeInput_ScanCodes:
        pDevice->inputs++;
        break;
      case kIOHIDElementTypeOutput:
        pDevice->outputs++;
        break;
      case kIOHIDElementTypeFeature:
        pDevice->features++;
        break;
      case kIOHIDElementTypeCollection:
        pDevice->collections++;
        break;
      default:
        HIDReportErrorNum ("Unknown element type : ", pElement->type);
    }

        if (NULL == *ppElementCurrent) // if at list head
    {
            pDevice->pListElements = pElement; // add current element
      *ppElementCurrent = pElement; // set current element to element we just added
    }
    else // have exsiting structure
    {
      if (gAddAsChild) // if the previous element was a collection, let's add this as a child of the previous
      {
        // this iteration should not be needed but there maybe some untested degenerate case which this code will ensure works
        while ((*ppElementCurrent)->pChild) // step down tree until free child node found
          *ppElementCurrent = (*ppElementCurrent)->pChild;
        (*ppElementCurrent)->pChild = pElement; // insert there
        pElement->depth = (*ppElementCurrent)->depth + 1;
      }
      else // add as sibling
      {
        // this iteration should not be needed but there maybe some untested degenerate case which this code will ensure works
        while ((*ppElementCurrent)->pSibling) // step down tree until free sibling node found
          *ppElementCurrent = (*ppElementCurrent)->pSibling;
        (*ppElementCurrent)->pSibling = pElement; // insert there
        pElement->depth = (*ppElementCurrent)->depth;
      }
      pElement->pPrevious = *ppElementCurrent; // point to previous
      *ppElementCurrent = pElement; // set current to our collection
    }

    if (elementType == kIOHIDElementTypeCollection) // if this element is a collection of other elements
    {
      gAddAsChild = true; // add next set as children to this element
      gDepth++;
      hid_GetCollectionElements ((CFMutableDictionaryRef) refElement, &pElement); // recursively process the collection
      gDepth--;
    }
    gAddAsChild = false; // add next as this elements sibling (when return from a collection or with non-collections)
    }
#if 0
    else
        HIDReportError ("hid_AddElement - no element added.");
#endif
}


static void hid_GetElementsCFArrayHandler (const void * value, void * parameter)
{
    if (CFGetTypeID (value) == CFDictionaryGetTypeID ())
        hid_AddElement ((CFTypeRef) value, (pRecElement *) parameter);
}

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

static void hid_GetElements (CFTypeRef refElementCurrent, pRecElement *ppCurrentElement)
{
    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, hid_GetElementsCFArrayHandler, ppCurrentElement);
    }
}

static void hid_TopLevelElementHandler (const void * value, void * parameter)
{
    CFTypeRef refCF = 0;
    if ((NULL == value) || (NULL == parameter))
        return; // (kIOReturnBadArgument)
    if (CFGetTypeID (value) != CFDictionaryGetTypeID ())
        return; // (kIOReturnBadArgument)
    refCF = CFDictionaryGetValue (value, CFSTR(kIOHIDElementUsagePageKey));
    if (!CFNumberGetValue (refCF, kCFNumberLongType, &((pRecDevice) parameter)->usagePage))
        HIDReportError ("CFNumberGetValue error retrieving pDevice->usagePage.");
    refCF = CFDictionaryGetValue (value, CFSTR(kIOHIDElementUsageKey));
    if (!CFNumberGetValue (refCF, kCFNumberLongType, &((pRecDevice) parameter)->usage))
        HIDReportError ("CFNumberGetValue error retrieving pDevice->usage.");
}


static void hid_GetDeviceInfo (io_object_t hidDevice, CFMutableDictionaryRef hidProperties, pRecDevice 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 transport
            refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDTransportKey));
            if (refCF)
            {
        if (!CFStringGetCString (refCF, pDevice->transport, 256, CFStringGetSystemEncoding ()))
                    HIDReportError ("CFStringGetCString error retrieving pDevice->transport.");
            }

            // get vendorID
            refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDVendorIDKey));
            if (!refCF)
                refCF = CFDictionaryGetValue (usbProperties, CFSTR("idVendor"));
            if (refCF)
            {
                if (!CFNumberGetValue (refCF, kCFNumberLongType, &pDevice->vendorID))
                    HIDReportError ("CFNumberGetValue error retrieving pDevice->vendorID.");
            }

            // get product ID
            refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDProductIDKey));
            if (!refCF)
                refCF = CFDictionaryGetValue (usbProperties, CFSTR("idProduct"));
            if (refCF)
            {
                if (!CFNumberGetValue (refCF, kCFNumberLongType, &pDevice->productID))
                    HIDReportError ("CFNumberGetValue error retrieving pDevice->productID.");
            }

            // get product version
            refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDVersionNumberKey));
            if (refCF)
            {
                if (!CFNumberGetValue (refCF, kCFNumberLongType, &pDevice->version))
                    HIDReportError ("CFNumberGetValue error retrieving pDevice->version.");
            }

            // get manufacturer name
            refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDManufacturerKey));
            if (!refCF)
                refCF = CFDictionaryGetValue (usbProperties, CFSTR("USB Vendor Name"));
            if (refCF)
            {
                if (!CFStringGetCString (refCF, pDevice->manufacturer, 256, CFStringGetSystemEncoding ()))
                    HIDReportError ("CFStringGetCString error retrieving pDevice->manufacturer.");
            }

            // 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 ()))
                    HIDReportError ("CFStringGetCString error retrieving pDevice->product.");
            }

            // get serial
            refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDSerialNumberKey));
            if (refCF)
            {
                if (!CFStringGetCString (refCF, pDevice->serial, 256, CFStringGetSystemEncoding ()))
                    HIDReportError ("CFStringGetCString error retrieving pDevice->serial.");
            }

            // get location ID
            refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDLocationIDKey));
            if (!refCF)
                refCF = CFDictionaryGetValue (usbProperties, CFSTR("locationID"));
            if (refCF)
            {
                if (!CFNumberGetValue (refCF, kCFNumberLongType, &pDevice->locID))
                    HIDReportError ("CFNumberGetValue error retrieving pDevice->locID.");
            }

            // get usage page and usage
            refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDPrimaryUsagePageKey));
            if (refCF)
            {
                if (!CFNumberGetValue (refCF, kCFNumberLongType, &pDevice->usagePage))
                    HIDReportError ("CFNumberGetValue error retrieving pDevice->usagePage.");
                refCF = CFDictionaryGetValue (hidProperties, CFSTR(kIOHIDPrimaryUsageKey));
                if (refCF)
                    if (!CFNumberGetValue (refCF, kCFNumberLongType, &pDevice->usage))
                        HIDReportError ("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, hid_TopLevelElementHandler, NULL);
                }
            }
        }
        else
            HIDReportError ("IORegistryEntryCreateCFProperties failed to create usbProperties.");

        CFRelease (usbProperties);
        if (kIOReturnSuccess != IOObjectRelease (parent2))
            HIDReportError ("IOObjectRelease error with parent2.");
        if (kIOReturnSuccess != IOObjectRelease (parent1))
            HIDReportError ("IOObjectRelease error with parent1.");
    }
}


static Boolean hid_MatchElementTypeMask (IOHIDElementType type, HIDElementTypeMask typeMask)
{
  if (typeMask & kHIDElementTypeInput)
    if ((type == kIOHIDElementTypeInput_Misc) || (type == kIOHIDElementTypeInput_Button) || (type == kIOHIDElementTypeInput_Axis) || (type == kIOHIDElementTypeInput_ScanCodes))
      return true;
  if (typeMask & kHIDElementTypeOutput)
    if (type == kIOHIDElementTypeOutput)
      return true;
  if (typeMask & kHIDElementTypeFeature)
    if (type == kIOHIDElementTypeFeature)
      return true;
  if (typeMask & kHIDElementTypeCollection)
    if (type == kIOHIDElementTypeCollection)
      return true;
  return false;
}

static pRecElement hid_GetDeviceElement (pRecElement pElement, HIDElementTypeMask typeMask)
{
  // we are asking for this element
    if (NULL != pElement)
  {
    if (hid_MatchElementTypeMask (pElement->type, typeMask)) // if the type match what we are looking for
      return pElement; // return the element
    else
      return HIDGetNextDeviceElement (pElement, typeMask); // else get the next one
  }
  return NULL;
}

static unsigned long HIDCloseReleaseInterface (pRecDevice pDevice)
{
  IOReturn result = kIOReturnSuccess;

  if (HIDIsValidDevice(pDevice) && (NULL != pDevice->interface))
  {
    // close the interface
    result = (*(IOHIDDeviceInterface**) 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 ("HIDCloseReleaseInterface - Failed to close IOHIDDeviceInterface.", result);
    //release the interface
    result = (*(IOHIDDeviceInterface**) pDevice->interface)->Release (pDevice->interface);
    if (kIOReturnSuccess != result)
      HIDREPORTERRORNUM ("HIDCloseReleaseInterface - Failed to release interface.", result);
    pDevice->interface = NULL;
  }
  return result;
}


// ---------------------------------
// count number of devices in global device list (gpDeviceList)
static UInt32 hid_CountCurrentDevices (void)
{
    pRecDevice pDevice = gpDeviceList;
    UInt32 devices = 0;
    while (pDevice)
    {
        devices++;
        pDevice = pDevice->pNext;
    }
    return devices;
}

static UInt32 HIDCountDevices (void)
{
  gNumDevices = hid_CountCurrentDevices ();

    return gNumDevices;
}

static void hid_DisposeDeviceElements (pRecElement pElement)
{
  if (pElement)
  {
    if (pElement->pChild)
      hid_DisposeDeviceElements (pElement->pChild);
    if (pElement->pSibling)
      hid_DisposeDeviceElements (pElement->pSibling);
    free (pElement);
  }
}

static pRecDevice hid_DisposeDevice (pRecDevice pDevice)
{
    kern_return_t result = KERN_SUCCESS;
    pRecDevice pDeviceNext = NULL;

    if (HIDIsValidDevice(pDevice))
    {
        // save next device prior to disposing of this device
        pDeviceNext = pDevice->pNext;

    result = HIDDequeueDevice (pDevice);
#if 0
    if (kIOReturnSuccess != result)
      HIDReportErrorNum ("hid_DisposeDevice: HIDDequeueDevice error: 0x%8.8X.", result);
#endif 1

        hid_DisposeDeviceElements (pDevice->pListElements);
    pDevice->pListElements = NULL;

    result = HIDCloseReleaseInterface (pDevice); // function sanity checks interface value (now application does not own device)
    if (kIOReturnSuccess != result)
      HIDReportErrorNum ("hid_DisposeDevice: HIDCloseReleaseInterface error: 0x%8.8X.", result);

#if USE_NOTIFICATIONS
        if (pDevice->interface)
        {
      // replace (*pDevice->interface)->Release(pDevice->interface);
      result = IODestroyPlugInInterface (pDevice->interface);
      if (kIOReturnSuccess != result)
        HIDReportErrorNum ("hid_DisposeDevice: IODestroyPlugInInterface error: 0x%8.8X.", result);
        }

        if (pDevice->notification)
    {
      result = IOObjectRelease((io_object_t) pDevice->notification);
      if (kIOReturnSuccess != result)
        HIDReportErrorNum ("hid_DisposeDevice: IOObjectRelease error: 0x%8.8X.", result);
    }
#endif USE_NOTIFICATIONS

    // remove this device from the device list
    if (gpDeviceList == pDevice)  // head of list?
      gpDeviceList = pDeviceNext;
    else
    {
      pRecDevice pDeviceTemp = pDeviceNext = gpDeviceList;  // we're going to return this if we don't find ourselfs in the list
      while (pDeviceTemp)
      {
        if (pDeviceTemp->pNext == pDevice) // found us!
        {
          // take us out of linked list
          pDeviceTemp->pNext = pDeviceNext = pDevice->pNext;
          break;
        }
        pDeviceTemp = pDeviceTemp->pNext;
      }
    }
        free (pDevice);
    }

  // update device count
  gNumDevices = hid_CountCurrentDevices ();

    return pDeviceNext;
}


// ---------------------------------
// disposes and releases queue, sets queue to NULL,.
// Note: will have no effect if device or queue do not exist

static IOReturn hid_DisposeReleaseQueue (pRecDevice pDevice)
{
    IOReturn result = kIOReturnError; // assume failure (pessimist!)

  if (HIDIsValidDevice(pDevice))  // need valid device
  {
    if (pDevice->queue) // and queue
    {
      // stop queue
      result = (*(IOHIDQueueInterface**) pDevice->queue)->stop (pDevice->queue);
      if (kIOReturnSuccess != result)
        HIDREPORTERRORNUM ("hid_DisposeReleaseQueue - Failed to stop queue.", result);
      // dispose of queue
      result = (*(IOHIDQueueInterface**) pDevice->queue)->dispose (pDevice->queue);
      if (kIOReturnSuccess != result)
        HIDREPORTERRORNUM ("hid_DisposeReleaseQueue - Failed to dipose queue.", result);
      // release the queue
      result = (*(IOHIDQueueInterface**) pDevice->queue)->Release (pDevice->queue);
      if (kIOReturnSuccess != result)
        HIDREPORTERRORNUM ("hid_DisposeReleaseQueue - Failed to release queue.", result);

      pDevice->queue = NULL;
    }
    else
      HIDREPORTERROR ("hid_DisposeReleaseQueue - no queue.");
  }
  else
    HIDREPORTERROR ("hid_DisposeReleaseQueue - Invalid device.");
    return result;
}


// ---------------------------------
// completely removes all elements from queue and releases queue and closes device interface
// does not release device interfaces, application must call HIDReleaseDeviceList on exit

static unsigned long  HIDDequeueDevice (pRecDevice pDevice)
{
    IOReturn result = kIOReturnSuccess;

    if (HIDIsValidDevice(pDevice))
  {
    if ((pDevice->interface) && (pDevice->queue))
    {
      // iterate through elements and if queued, remove
      pRecElement pElement = HIDGetFirstDeviceElement (pDevice, kHIDElementTypeIO);
      while (pElement)
      {
        if ((*(IOHIDQueueInterface**) pDevice->queue)->hasElement (pDevice->queue, pElement->cookie))
        {
          result = (*(IOHIDQueueInterface**) pDevice->queue)->removeElement (pDevice->queue, pElement->cookie);
          if (kIOReturnSuccess != result)
            HIDREPORTERRORNUM ("HIDDequeueDevice - Failed to remove element from queue.", result);
        }
        pElement = HIDGetNextDeviceElement (pElement, kHIDElementTypeIO);
      }
    }
    // ensure queue is disposed and released
    // interface will be closed and released on call to HIDReleaseDeviceList
    result = hid_DisposeReleaseQueue (pDevice);
    if (kIOReturnSuccess != result)
      HIDREPORTERRORNUM ("removeElement - Failed to dispose and release queue.", result);
#if USE_ASYNC_EVENTS
    else if (NULL != pDevice->queueRunLoopSource)
    {
      if (CFRunLoopContainsSource(CFRunLoopGetCurrent(), pDevice->queueRunLoopSource, kCFRunLoopDefaultMode))
        CFRunLoopRemoveSource(CFRunLoopGetCurrent(), pDevice->queueRunLoopSource, kCFRunLoopDefaultMode);
      CFRelease(pDevice->queueRunLoopSource);
      pDevice->queueRunLoopSource = NULL;
    }
#endif USE_ASYNC_EVENTS
  }
  else
  {
    HIDREPORTERROR ("HIDDequeueDevice - Invalid device.");
    result = kIOReturnBadArgument;
  }
    return result;
}

// ---------------------------------
// releases all device queues for quit or rebuild (must be called)
// does not release device interfaces, application must call HIDReleaseDeviceList on exit

static unsigned long HIDReleaseAllDeviceQueues (void)
{
    IOReturn result = kIOReturnBadArgument;
    pRecDevice pDevice = HIDGetFirstDevice ();

    while (pDevice)
    {
        result = HIDDequeueDevice (pDevice);
        if (kIOReturnSuccess != result)
            HIDREPORTERRORNUM ("HIDReleaseAllDeviceQueues - Could not dequeue device.", result);
        pDevice = HIDGetNextDevice (pDevice);
    }
    return result;
}


// ---------------------------------
// Get the next event in the queue for a device
// elements or entire device should be queued prior to calling this with HIDQueueElement or HIDQueueDevice
// returns true if an event is avialable for the element and fills out *pHIDEvent structure, returns false otherwise
// Note: kIOReturnUnderrun returned from getNextEvent indicates an empty queue not an error condition
// Note: application should pass in a pointer to a IOHIDEventStruct cast to a void (for CFM compatibility)

static unsigned char HIDGetEvent (pRecDevice pDevice, void * pHIDEvent)
{
    IOReturn result = kIOReturnBadArgument;
    AbsoluteTime zeroTime = {0,0};

    if (HIDIsValidDevice(pDevice))
  {
    if (pDevice->queue)
    {
      result = (*(IOHIDQueueInterface**) pDevice->queue)->getNextEvent (pDevice->queue, (IOHIDEventStruct *)pHIDEvent, zeroTime, 0);
      if (kIOReturnUnderrun == result)
        return false;  // no events in queue not an error per say
      else if (kIOReturnSuccess != result) // actual error versus just an empty queue
        HIDREPORTERRORNUM ("HIDGetEvent - Could not get HID event via getNextEvent.", result);
      else
        return true;
    }
    else
      HIDREPORTERROR ("HIDGetEvent - queue does not exist.");
  }
  else
    HIDREPORTERROR ("HIDGetEvent - invalid device.");

    return false; // did not get event
}


static unsigned long HIDCreateOpenDeviceInterface (UInt32 hidDevice, pRecDevice 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 ("CouldnÕt query HID class device interface from plugInInterface", plugInResult);
      IODestroyPlugInInterface (ppPlugInInterface); // replace (*ppPlugInInterface)->Release (ppPlugInInterface)
    }
    else
      HIDReportErrorNum ("Failed to create **plugInInterface via IOCreatePlugInInterfaceForService.", result);
  }
  if (NULL != pDevice->interface)
  {
    result = (*(IOHIDDeviceInterface**)pDevice->interface)->open (pDevice->interface, 0);
    if (kIOReturnSuccess != result)
      HIDReportErrorNum ("Failed to open pDevice->interface via open.", result);
  }
    return result;
}


// ---------------------------------
// adds device to linked list of devices passed in (handles NULL lists properly)
// (returns where you just stored it)
static pRecDevice* hid_AddDevice (pRecDevice *ppListDeviceHead, pRecDevice pNewDevice)
{
  pRecDevice* result = NULL;

    if (NULL == *ppListDeviceHead)
        result = ppListDeviceHead;
    else
    {
        pRecDevice pDevicePrevious = NULL, pDevice = *ppListDeviceHead;
        while (pDevice)
        {
            pDevicePrevious = pDevice;
            pDevice = pDevicePrevious->pNext;
        }
        result = &pDevicePrevious->pNext;
    }
    pNewDevice->pNext = NULL;

  *result = pNewDevice;

  return result;
}

static pRecDevice hid_BuildDevice (io_object_t hidDevice)
{
    pRecDevice pDevice = (pRecDevice) malloc (sizeof (recDevice));

    if (NULL != pDevice)
    {
    // get dictionary for HID properties
        CFMutableDictionaryRef hidProperties = 0;
        kern_return_t result = IORegistryEntryCreateCFProperties (hidDevice, &hidProperties, kCFAllocatorDefault, kNilOptions);

    // clear record
    bzero(pDevice, sizeof(recDevice));

        if ((result == KERN_SUCCESS) && (NULL != hidProperties))
        {
      pRecElement pCurrentElement = NULL;
      // create device interface
      result = HIDCreateOpenDeviceInterface (hidDevice, pDevice);
      if (kIOReturnSuccess != result)
        HIDReportErrorNum ("HIDCreateOpenDeviceInterface failed.", result);
            hid_GetDeviceInfo (hidDevice, hidProperties, pDevice); // hidDevice used to find parents in registry tree
                                   // set current device for use in getting elements
      gCurrentGetDevice = pDevice;
      // Add all elements
            hid_GetCollectionElements (hidProperties, &pCurrentElement);
      gCurrentGetDevice = NULL;
            CFRelease (hidProperties);
        }
        else
            HIDReportErrorNum ("IORegistryEntryCreateCFProperties error when creating deviceProperties.", result);
    }
    else
        HIDReportError ("malloc error when allocating pRecDevice.");
    return pDevice;
}



#if USE_NOTIFICATIONS
//================================================================================================
//
//  hid_DeviceNotification
//
//  This routine will get called whenever any kIOGeneralInterest notification happens.  We are
//  interested in the kIOMessageServiceIsTerminated message so that's what we look for.  Other
//  messages are defined in IOMessage.h.
//
//================================================================================================
//
static void hid_DeviceNotification( void *refCon,
                  io_service_t service,
                  natural_t messageType,
                  void *messageArgument )
{
    pRecDevice pDevice = (pRecDevice) refCon;

    if (messageType == kIOMessageServiceIsTerminated)
    {
        //printf("Device 0x%08x \"%s\"removed.\n", service, pDevice->product);
        // ryan added this.
        if (pDevice->disconnect == DISCONNECT_CONNECTED)
          pDevice->disconnect = DISCONNECT_TELLUSER;

        // Free the data we're no longer using now that the device is going away
        // ryan commented this out.
    //hid_DisposeDevice (pDevice);
    }
}
#else

static void hid_RemovalCallbackFunction(void * target, IOReturn result, void * refcon, void * sender)
{
    // ryan commented this out.
  //hid_DisposeDevice ((pRecDevice) target);

    // ryan added this.
    pRecDevice = (pRecDevice) target;
    if (pDevice->disconnect == DISCONNECT_CONNECTED)
        pDevice->disconnect = DISCONNECT_TELLUSER;
}

#endif USE_NOTIFICATIONS



static void hid_AddDevices (void *refCon, io_iterator_t iterator)
{
  // NOTE: refcon passed in is used to point to the device list head
    pRecDevice* pListDeviceHead = (pRecDevice*) refCon;
    IOReturn result = kIOReturnSuccess;
    io_object_t ioHIDDeviceObject = 0;

    while ((ioHIDDeviceObject = IOIteratorNext (iterator)) != 0)
    {
    pRecDevice* pNewDeviceAt = NULL;
    pRecDevice pNewDevice = hid_BuildDevice (ioHIDDeviceObject);
    if (pNewDevice)
    {
#if 0 // set true for verbose output
      printf("\nhid_AddDevices: pNewDevice = {t: \"%s\", v: %ld, p: %ld, v: %ld, m: \"%s\", " \
      "p: \"%s\", l: %ld, u: %4.4lX:%4.4lX, #e: %ld, #f: %ld, #i: %ld, #o: %ld, " \
      "#c: %ld, #a: %ld, #b: %ld, #h: %ld, #s: %ld, #d: %ld, #w: %ld}.",
      pNewDevice->transport,
      pNewDevice->vendorID,
      pNewDevice->productID,
      pNewDevice->version,
      pNewDevice->manufacturer,
      pNewDevice->product,
      pNewDevice->locID,
      pNewDevice->usagePage,
      pNewDevice->usage,
      pNewDevice->totalElements,
      pNewDevice->features,
      pNewDevice->inputs,
      pNewDevice->outputs,
      pNewDevice->collections,
      pNewDevice->axis,
      pNewDevice->buttons,
      pNewDevice->hats,
      pNewDevice->sliders,
      pNewDevice->dials,
      pNewDevice->wheels
      );
      fflush(stdout);
#elif 0 // otherwise output brief description
      printf("\nhid_AddDevices: pNewDevice = {m: \"%s\" p: \"%s\", vid: %ld, pid: %ld, loc: %8.8lX, usage: %4.4lX:%4.4lX}.",
      pNewDevice->manufacturer,
      pNewDevice->product,
      pNewDevice->vendorID,
      pNewDevice->productID,
      pNewDevice->locID,
      pNewDevice->usagePage,
      pNewDevice->usage
      );
      fflush(stdout);
#endif
      pNewDeviceAt = hid_AddDevice (pListDeviceHead, pNewDevice);
    }

#if USE_NOTIFICATIONS
        // Register for an interest notification of this device being removed. Use a reference to our
        // private data as the refCon which will be passed to the notification callback.
        result = IOServiceAddInterestNotification( gNotifyPort,         // notifyPort
                           ioHIDDeviceObject,     // service
                           kIOGeneralInterest,      // interestType
                           hid_DeviceNotification,    // callback
                           pNewDevice,          // refCon
                           (io_object_t*) &pNewDevice->notification); // notification
    if (KERN_SUCCESS != result)
      HIDReportErrorNum ("hid_AddDevices: IOServiceAddInterestNotification error: x0%8.8lX.", result);
#else
    result = (*(IOHIDDeviceInterface**)pNewDevice->interface)->setRemovalCallback (pNewDevice->interface, hid_RemovalCallbackFunction,pNewDeviceAt,0);
#endif USE_NOTIFICATIONS

    // release the device object, it is no longer needed
    result = IOObjectRelease (ioHIDDeviceObject);
    if (KERN_SUCCESS != result)
      HIDReportErrorNum ("hid_AddDevices: IOObjectRelease error with ioHIDDeviceObject.", result);
    }
}


static Boolean HIDBuildDeviceList (UInt32 usagePage, UInt32 usage)
{
    IOReturn result = kIOReturnSuccess;
    mach_port_t masterPort = 0;

    if (NULL != gpDeviceList)
        HIDReleaseDeviceList ();

    result = IOMasterPort (bootstrap_port, &masterPort);
    if (kIOReturnSuccess != result)
        HIDReportErrorNum ("IOMasterPort error with bootstrap_port.", result);
    else
    {
    CFMutableDictionaryRef hidMatchDictionary = NULL;

    // Set up matching dictionary to search the I/O Registry for HID devices we are interested in. Dictionary reference is NULL if error.
    {
      CFNumberRef refUsage = NULL, refUsagePage = NULL;

      // Set up a matching dictionary to search I/O Registry by class name for all HID class devices.
      hidMatchDictionary = IOServiceMatching (kIOHIDDeviceKey);
      if (NULL != hidMatchDictionary)
      {
        if (usagePage)
        {
          // Add key for device type (joystick, in this case) to refine the matching dictionary.
          refUsagePage = CFNumberCreate (kCFAllocatorDefault, kCFNumberLongType, &usagePage);
          CFDictionarySetValue (hidMatchDictionary, CFSTR (kIOHIDPrimaryUsagePageKey), refUsagePage);
          CFRelease (refUsagePage);
          if (usage)
          {
            refUsage = CFNumberCreate (kCFAllocatorDefault, kCFNumberLongType, &usage);
            CFDictionarySetValue (hidMatchDictionary, CFSTR (kIOHIDPrimaryUsageKey), refUsage);
            CFRelease (refUsage);
          }
        }
        CFRetain(hidMatchDictionary);
      }
      else
        HIDReportError ("Failed to get HID CFMutableDictionaryRef via IOServiceMatching.");
    }

#if USE_NOTIFICATIONS
    // Create a notification port and add its run loop event source to our run loop
    // This is how async notifications get set up.
    {
      CFRunLoopSourceRef    runLoopSource;

      gNotifyPort = IONotificationPortCreate(masterPort);
      runLoopSource = IONotificationPortGetRunLoopSource(gNotifyPort);

      gRunLoop = CFRunLoopGetCurrent();
      CFRunLoopAddSource(gRunLoop, runLoopSource, kCFRunLoopDefaultMode);

      // Now set up a notification to be called when a device is first matched by I/O Kit.
      result = IOServiceAddMatchingNotification(gNotifyPort,      // notifyPort
                       kIOFirstMatchNotification,   // notificationType
                       hidMatchDictionary,      // matching
                       hid_AddDevices,        // callback
                       &gpDeviceList,         // refCon
                       &gAddedIter          // notification
                       );

      // call it now to add all existing devices
      hid_AddDevices(&gpDeviceList,gAddedIter);
            return true;
    }
#else
    {
      io_iterator_t hidObjectIterator = NULL;

      // Now search I/O Registry for matching devices.
      result = IOServiceGetMatchingServices (masterPort, hidMatchDictionary, &hidObjectIterator);
      if (kIOReturnSuccess != result)
        HIDReportErrorNum ("Failed to create IO object iterator, error:", result);
      else if (NULL == hidObjectIterator) // likely no HID devices which matched selection criteria are connected
        HIDReportError ("Warning: Could not find any matching devices, thus iterator creation failed.");

      if (NULL != hidObjectIterator)
      {
        hid_AddDevices(&gpDeviceList,hidObjectIterator);

        result = IOObjectRelease (hidObjectIterator); // release the iterator
        if (kIOReturnSuccess != result)
          HIDReportErrorNum ("IOObjectRelease error with hidObjectIterator.", result);

        gNumDevices = hid_CountCurrentDevices ();
        return true;
      }
    }
#endif USE_NOTIFICATIONS
    // IOServiceGetMatchingServices consumes a reference to the dictionary, so we don't need to release the dictionary ref.
    hidMatchDictionary = NULL;
    }
  return false;
}

// ---------------------------------
// release list built by above function
// MUST be called prior to application exit to properly release devices
// if not called (or app crashes) devices can be recovered by pluging into different location in USB chain

static void HIDReleaseDeviceList (void)
{
    while (NULL != gpDeviceList)
    gpDeviceList = hid_DisposeDevice (gpDeviceList); // dispose current device return next device will set gpDeviceList to NULL
    gNumDevices = 0;
}

// ---------------------------------
// get the first device in the device list
// returns NULL if no list exists

static pRecDevice HIDGetFirstDevice (void)
{
    return gpDeviceList;
}

// ---------------------------------
// get next device in list given current device as parameter
// returns NULL if end of list

static pRecDevice HIDGetNextDevice (pRecDevice pDevice)
{
    if (NULL != pDevice)
        return pDevice->pNext;
    else
        return NULL;
}

// ---------------------------------
// get the first element of device passed in as parameter
// returns NULL if no list exists or device does not exists or is NULL
static pRecElement HIDGetFirstDeviceElement (pRecDevice pDevice, HIDElementTypeMask typeMask)
{
    if (HIDIsValidDevice(pDevice))
  {
        if (hid_MatchElementTypeMask (pDevice->pListElements->type, typeMask)) // ensure first type matches
      return pDevice->pListElements;
    else
      return HIDGetNextDeviceElement (pDevice->pListElements, typeMask);
  }
    else
        return NULL;
}

// ---------------------------------
// get next element of given device in list given current element as parameter
// will walk down each collection then to next element or collection (depthwise traverse)
// returns NULL if end of list
// uses mask of HIDElementTypeMask to restrict element found
// use kHIDElementTypeIO to get previous HIDGetNextDeviceElement functionality
static pRecElement HIDGetNextDeviceElement (pRecElement pElement, HIDElementTypeMask typeMask)
{
  // should only have elements passed in (though someone could mix calls and pass us a collection)
  // collection means return the next child or sibling (in that order)
  // element means returnt he next sibling (as elements can't have children
    if (NULL != pElement)
  {
    if (pElement->pChild)
    {
      if (pElement->type != kIOHIDElementTypeCollection)
        HIDReportError ("Malformed element list: found child of element.");
      else
        return hid_GetDeviceElement (pElement->pChild, typeMask); // return the child of this element
    }
    else if (pElement->pSibling)
    {
      return hid_GetDeviceElement (pElement->pSibling, typeMask); //return the sibling of this element
    }
    else // at end back up correctly
    {
      pRecElement pPreviousElement = NULL;
      // malformed device ending in collection
      if (pElement->type == kIOHIDElementTypeCollection)
        HIDReportError ("Malformed device: found collection at end of element chain.");
      // walk back up tree to element prior to first collection ecountered and take next element
      while (NULL != pElement->pPrevious)
      {
        pPreviousElement = pElement;
        pElement = pElement->pPrevious; // look at previous element
                  // if we have a collection and the previous element is the branch element (should have both a colection and next element attached to it)
     // if we found a collection, which we are not at the sibling level that actually does have siblings
        if (((pElement->type == kIOHIDElementTypeCollection) && (pPreviousElement != pElement->pSibling) && pElement->pSibling) ||
    // or if we are at the top
    (NULL == pElement->pPrevious)) // at top of tree
          break;
      }
      if (NULL == pElement->pPrevious)
        return NULL; // got to top of list with only a collection as the first element
         // now we must have been down the child route so go down the sibling route
      pElement = pElement->pSibling; // element of interest
      return hid_GetDeviceElement (pElement, typeMask); // otherwise return this element
    }
  }
  return NULL;
}


// return true if this is a valid device pointer
Boolean HIDIsValidDevice(const pRecDevice pSearchDevice)
{
  pRecDevice pDevice = gpDeviceList;

  while (pDevice)
  {
    if (pDevice == pSearchDevice)
      return true;
    pDevice = pDevice->pNext;
  }
  return false;
}


static IOReturn hid_CreateQueue (pRecDevice pDevice)
{
    IOReturn result = kIOReturnError; // assume failure (pessimist!)

  if (HIDIsValidDevice(pDevice))
  {
    if (NULL == pDevice->queue) // do we already have a queue
    {
      if (NULL != pDevice->interface)
      {
        pDevice->queue = (void *) (*(IOHIDDeviceInterface**) pDevice->interface)->allocQueue (pDevice->interface); // alloc queue
        if (pDevice->queue)
        {
          result = (*(IOHIDQueueInterface**) pDevice->queue)->create (pDevice->queue, 0, kDeviceQueueSize); // create actual queue
          if (kIOReturnSuccess != result)
            HIDREPORTERRORNUM ("hid_CreateQueue - Failed to create queue via create", result);
        }
        else
        {
          HIDREPORTERROR ("hid_CreateQueue - Failed to alloc IOHIDQueueInterface ** via allocQueue");
          result = kIOReturnError; // synthesis error
        }
      }
      else
        HIDREPORTERRORNUM ("hid_CreateQueue - Device inteface does not exist for queue creation", result);
    }
  }
  else
    HIDREPORTERRORNUM ("hid_CreateQueue - Invalid Device", result);
    return result;
}

static unsigned long  HIDQueueDevice (pRecDevice pDevice)
{
    IOReturn result = kIOReturnError; // assume failure (pessimist!)
    pRecElement pElement;

  if (HIDIsValidDevice(pDevice))
  {
    // error checking
    if (NULL == pDevice)
    {
      HIDREPORTERROR ("HIDQueueDevice - Device does not exist.");
      return kIOReturnBadArgument;
    }
    if (NULL == pDevice->interface) // must have interface
    {
      HIDREPORTERROR ("HIDQueueDevice - Device does not have interface.");
      return kIOReturnError;
    }
    if (NULL == pDevice->queue) // if no queue create queue
      result = hid_CreateQueue (pDevice);
    if ((kIOReturnSuccess != result) || (NULL == pDevice->queue))
    {
      HIDREPORTERRORNUM ("HIDQueueDevice - problem creating queue.", result);
      if (kIOReturnSuccess != result)
        return result;
      else
        return kIOReturnError;
    }

    // stop queue
    result = (*(IOHIDQueueInterface**) pDevice->queue)->stop (pDevice->queue);
    if (kIOReturnSuccess != result)
      HIDREPORTERRORNUM ("HIDQueueDevice - Failed to stop queue.", result);

    // queue element
  //¥ pElement = HIDGetFirstDeviceElement (pDevice, kHIDElementTypeIO);
    pElement = HIDGetFirstDeviceElement (pDevice, kHIDElementTypeInput | kHIDElementTypeFeature);

    while (pElement)
    {
      if (!(*(IOHIDQueueInterface**) pDevice->queue)->hasElement (pDevice->queue, pElement->cookie))
      {
        result = (*(IOHIDQueueInterface**) pDevice->queue)->addElement (pDevice->queue, pElement->cookie, 0);
        if (kIOReturnSuccess != result)
          HIDREPORTERRORNUM ("HIDQueueDevice - Failed to add element to queue.", result);
      }
      //¥ pElement = HIDGetNextDeviceElement (pElement, kHIDElementTypeIO);
      pElement = HIDGetNextDeviceElement (pElement, kHIDElementTypeInput | kHIDElementTypeFeature);
    }

    // start queue
    result = (*(IOHIDQueueInterface**) pDevice->queue)->start (pDevice->queue);
    if (kIOReturnSuccess != result)
      HIDREPORTERRORNUM ("HIDQueueDevice - Failed to start queue.", result);

  }
  else
    HIDREPORTERROR ("HIDQueueDevice - Invalid device.");

    return result;
}


/* -- END HID UTILITIES -- */


static int available_mice = 0;
static pRecDevice *devices = NULL;


/* returns non-zero if (a <= b). */
typedef unsigned long long ui64;
static inline int oldEvent(const AbsoluteTime *a, const AbsoluteTime *b)
{
#if 0  // !!! FIXME: doesn't work, timestamps aren't reliable.
    const ui64 a64 = (((unsigned long long) a->hi) << 32) | a->lo;
    const ui64 b64 = (((unsigned long long) b->hi) << 32) | b->lo;
#endif
    return 0;
} /* oldEvent */

static int poll_mouse(pRecDevice mouse, ManyMouseEvent *outevent)
{
    int unhandled = 1;
    while (unhandled)  /* read until failure or valid event. */
    {
        pRecElement recelem;
        IOHIDEventStruct event;

        if (!HIDGetEvent(mouse, &event))
            return(0);  /* no new event. */

        unhandled = 0;  /* will reset if necessary. */
        recelem = HIDGetFirstDeviceElement(mouse, kHIDElementTypeInput);
        while (recelem != NULL)
        {
            if (recelem->cookie == event.elementCookie)
                break;
            recelem = HIDGetNextDeviceElement(recelem, kHIDElementTypeInput);
        } /* while */

        if (recelem == NULL)
            continue;  /* unknown device element. Can this actually happen? */

        outevent->value = event.value;
        if (recelem->usagePage == kHIDPage_GenericDesktop)
        {
            /*
             * some devices (two-finger-scroll trackpads?) seem to give
             *  a flood of events with values of zero for every legitimate
             *  event. Throw these zero events out.
             */
            if (outevent->value == 0)
                unhandled = 1;
            else
            {
                switch (recelem->usage)
                {
                    case kHIDUsage_GD_X:
                    case kHIDUsage_GD_Y:
                        if (oldEvent(&event.timestamp, &mouse->lastScrollTime))
                            unhandled = 1;
                        else
                        {
                            outevent->type = MANYMOUSE_EVENT_RELMOTION;
                            if (recelem->usage == kHIDUsage_GD_X)
                                outevent->item = 0;
                            else
                                outevent->item = 1;
                        } /* else */
                        break;

                    case kHIDUsage_GD_Wheel:
                        memcpy(&mouse->lastScrollTime, &event.timestamp,
                               sizeof (AbsoluteTime));
                        outevent->type = MANYMOUSE_EVENT_SCROLL;
                        outevent->item = 0;  /* !!! FIXME: horiz scroll? */
                        break;

                    default:  /* !!! FIXME: absolute motion? */
                        unhandled = 1;
                } /* switch */
            } /* else */
        } /* if */

        else if (recelem->usagePage == kHIDPage_Button)
        {
            outevent->type = MANYMOUSE_EVENT_BUTTON;
            outevent->item = ((int) recelem->usage) - 1;
        } /* else if */

        else
        {
            unhandled = 1;
        } /* else */
    } /* while */

    return(1);  /* got a valid event */
} /* poll_mouse */


static void macosx_hidmanager_quit(void)
{
    HIDReleaseAllDeviceQueues();
    HIDReleaseDeviceList();
    free(devices);
    devices = NULL;
    available_mice = 0;
} /* macosx_hidmanager_quit */


static int macosx_hidmanager_init(void)
{
    macosx_hidmanager_quit();  /* just in case... */

    if (!HIDBuildDeviceList(kHIDPage_GenericDesktop, kHIDUsage_GD_Mouse))
        return(-1);

    available_mice = HIDCountDevices();
    if (available_mice > 0)
    {
        int i;
        pRecDevice dev = NULL;

        dev = HIDGetFirstDevice();
        devices = (pRecDevice *) malloc(sizeof (pRecDevice) * available_mice);
        if ((devices == NULL) || (dev == NULL))
        {
            macosx_hidmanager_quit();
            return(-1);
        } /* if */

        for (i = 0; i < available_mice; i++)
        {
            if (dev == NULL)  /* what? list ended? Truncate final list... */
                available_mice = i;

            if (HIDQueueDevice(dev) == kIOReturnSuccess)
                devices[i] = dev;
            else  /* failed? Chop this device from the list... */
            {
                i--;
                available_mice--;
            } /* else */

            dev = HIDGetNextDevice(dev);
        } /* for */
    } /* if */

    return(available_mice);
} /* macosx_hidmanager_init */


static const char *macosx_hidmanager_name(unsigned int index)
{
    if (index >= available_mice)
        return(NULL);

    return((const char *) devices[index]->product);
} /* macosx_hidmanager_name */


static int macosx_hidmanager_poll(ManyMouseEvent *event)
{
    /*
     * (i) is static so we iterate through all mice round-robin. This
     *  prevents a chatty mouse from dominating the queue.
     */
    static unsigned int i = 0;

    if (i >= available_mice)
        i = 0;  /* handle reset condition. */

    if (event != NULL)
    {
        while (i < available_mice)
        {
            pRecDevice dev = devices[i];
            if ((dev) && (dev->disconnect != DISCONNECT_COMPLETE))
            {
                event->device = i;

                /* see if mouse was unplugged since last polling... */
                if (dev->disconnect == DISCONNECT_TELLUSER)
                {
                    dev->disconnect = DISCONNECT_COMPLETE;
                    event->type = MANYMOUSE_EVENT_DISCONNECT;
                    return(1);
                } /* if */

                if (poll_mouse(dev, event))
                    return(1);
            } /* if */
            i++;
        } /* while */
    } /* if */

    return(0);  /* no new events */
} /* macosx_hidmanager_poll */

#else

static int macosx_hidmanager_init(void) { return(-1); }
static void macosx_hidmanager_quit(void) {}
static const char *macosx_hidmanager_name(unsigned int index) { return(0); }
static int macosx_hidmanager_poll(ManyMouseEvent *event) { return(0); }

#endif  /* MacOSX blocker */

ManyMouseDriver ManyMouseDriver_hidmanager =
{
    macosx_hidmanager_init,
    macosx_hidmanager_quit,
    macosx_hidmanager_name,
    macosx_hidmanager_poll
};

/* end of macosx_hidmanager.c ... */

