device/gamepad/gamepad_platform_data_fetcher_mac.mm - chromium/src - Git at Google

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "device/gamepad/gamepad_platform_data_fetcher_mac.h"

 #include <stdint.h>
 #include <string.h>

 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"

 #import <Foundation/Foundation.h>
 #include <IOKit/hid/IOHIDKeys.h>

 namespace device {

 namespace {

 void CopyNSStringAsUTF16LittleEndian(NSString* src,
                                      UChar* dest,
                                      size_t dest_len) {
   NSData* as16 = [src dataUsingEncoding:NSUTF16LittleEndianStringEncoding];
   memset(dest, 0, dest_len);
   [as16 getBytes:dest length:dest_len - sizeof(UChar)];
 }

 NSDictionary* DeviceMatching(uint32_t usage_page, uint32_t usage) {
   return [NSDictionary
       dictionaryWithObjectsAndKeys:[NSNumber numberWithUnsignedInt:usage_page],
                                    base::mac::CFToNSCast(
                                        CFSTR(kIOHIDDeviceUsagePageKey)),
                                    [NSNumber numberWithUnsignedInt:usage],
                                    base::mac::CFToNSCast(
                                        CFSTR(kIOHIDDeviceUsageKey)),
                                    nil];
 }

 float NormalizeAxis(CFIndex value, CFIndex min, CFIndex max) {
   return (2.f * (value - min) / static_cast<float>(max - min)) - 1.f;
 }

 float NormalizeUInt8Axis(uint8_t value, uint8_t min, uint8_t max) {
   return (2.f * (value - min) / static_cast<float>(max - min)) - 1.f;
 }

 float NormalizeUInt16Axis(uint16_t value, uint16_t min, uint16_t max) {
   return (2.f * (value - min) / static_cast<float>(max - min)) - 1.f;
 }

 float NormalizeUInt32Axis(uint32_t value, uint32_t min, uint32_t max) {
   return (2.f * (value - min) / static_cast<float>(max - min)) - 1.f;
 }

 // http://www.usb.org/developers/hidpage
 const uint32_t kGenericDesktopUsagePage = 0x01;
 const uint32_t kGameControlsUsagePage = 0x05;
 const uint32_t kButtonUsagePage = 0x09;
 const uint32_t kJoystickUsageNumber = 0x04;
 const uint32_t kGameUsageNumber = 0x05;
 const uint32_t kMultiAxisUsageNumber = 0x08;
 const uint32_t kAxisMinimumUsageNumber = 0x30;

 }  // namespace

 GamepadPlatformDataFetcherMac::GamepadPlatformDataFetcherMac()
     : enabled_(true), paused_(false) {
   memset(associated_, 0, sizeof(associated_));
 }

 GamepadSource GamepadPlatformDataFetcherMac::source() {
   return Factory::static_source();
 }

 void GamepadPlatformDataFetcherMac::OnAddedToProvider() {
   hid_manager_ref_.reset(
       IOHIDManagerCreate(kCFAllocatorDefault, kIOHIDOptionsTypeNone));
   if (CFGetTypeID(hid_manager_ref_) != IOHIDManagerGetTypeID()) {
     enabled_ = false;
     return;
   }

   base::scoped_nsobject<NSArray> criteria(
       [[NSArray alloc] initWithObjects:DeviceMatching(kGenericDesktopUsagePage,
                                                       kJoystickUsageNumber),
                                        DeviceMatching(kGenericDesktopUsagePage,
                                                       kGameUsageNumber),
                                        DeviceMatching(kGenericDesktopUsagePage,
                                                       kMultiAxisUsageNumber),
                                        nil]);
   IOHIDManagerSetDeviceMatchingMultiple(hid_manager_ref_,
                                         base::mac::NSToCFCast(criteria));

   RegisterForNotifications();
 }

 void GamepadPlatformDataFetcherMac::RegisterForNotifications() {
   // Register for plug/unplug notifications.
   IOHIDManagerRegisterDeviceMatchingCallback(hid_manager_ref_,
                                              DeviceAddCallback, this);
   IOHIDManagerRegisterDeviceRemovalCallback(hid_manager_ref_,
                                             DeviceRemoveCallback, this);

   // Register for value change notifications.
   IOHIDManagerRegisterInputValueCallback(hid_manager_ref_, ValueChangedCallback,
                                          this);

   IOHIDManagerScheduleWithRunLoop(hid_manager_ref_, CFRunLoopGetMain(),
                                   kCFRunLoopDefaultMode);

   enabled_ = IOHIDManagerOpen(hid_manager_ref_, kIOHIDOptionsTypeNone) ==
              kIOReturnSuccess;
 }

 void GamepadPlatformDataFetcherMac::UnregisterFromNotifications() {
   IOHIDManagerUnscheduleFromRunLoop(hid_manager_ref_, CFRunLoopGetCurrent(),
                                     kCFRunLoopDefaultMode);
   IOHIDManagerClose(hid_manager_ref_, kIOHIDOptionsTypeNone);
 }

 void GamepadPlatformDataFetcherMac::PauseHint(bool pause) {
   paused_ = pause;
 }

 GamepadPlatformDataFetcherMac::~GamepadPlatformDataFetcherMac() {
   UnregisterFromNotifications();
 }

 GamepadPlatformDataFetcherMac*
 GamepadPlatformDataFetcherMac::InstanceFromContext(void* context) {
   return reinterpret_cast<GamepadPlatformDataFetcherMac*>(context);
 }

 void GamepadPlatformDataFetcherMac::DeviceAddCallback(void* context,
                                                       IOReturn result,
                                                       void* sender,
                                                       IOHIDDeviceRef ref) {
   InstanceFromContext(context)->DeviceAdd(ref);
 }

 void GamepadPlatformDataFetcherMac::DeviceRemoveCallback(void* context,
                                                          IOReturn result,
                                                          void* sender,
                                                          IOHIDDeviceRef ref) {
   InstanceFromContext(context)->DeviceRemove(ref);
 }

 void GamepadPlatformDataFetcherMac::ValueChangedCallback(void* context,
                                                          IOReturn result,
                                                          void* sender,
                                                          IOHIDValueRef ref) {
   InstanceFromContext(context)->ValueChanged(ref);
 }

 bool GamepadPlatformDataFetcherMac::CheckCollection(IOHIDElementRef element) {
   // Check that a parent collection of this element matches one of the usage
   // numbers that we are looking for.
   while ((element = IOHIDElementGetParent(element)) != NULL) {
     uint32_t usage_page = IOHIDElementGetUsagePage(element);
     uint32_t usage = IOHIDElementGetUsage(element);
     if (usage_page == kGenericDesktopUsagePage) {
       if (usage == kJoystickUsageNumber || usage == kGameUsageNumber ||
           usage == kMultiAxisUsageNumber) {
         return true;
       }
     }
   }
   return false;
 }

 bool GamepadPlatformDataFetcherMac::AddButtonsAndAxes(NSArray* elements,
                                                       PadState* state,
                                                       size_t slot) {
   Gamepad& pad = state->data;
   AssociatedData& associated = associated_[slot];

   pad.axes_length = 0;
   pad.buttons_length = 0;
   pad.timestamp = 0;
   memset(pad.axes, 0, sizeof(pad.axes));
   memset(pad.buttons, 0, sizeof(pad.buttons));

   bool mapped_all_axes = true;

   for (id elem in elements) {
     IOHIDElementRef element = reinterpret_cast<IOHIDElementRef>(elem);
     if (!CheckCollection(element))
       continue;

     uint32_t usage_page = IOHIDElementGetUsagePage(element);
     uint32_t usage = IOHIDElementGetUsage(element);
     if (IOHIDElementGetType(element) == kIOHIDElementTypeInput_Button &&
         usage_page == kButtonUsagePage) {
       uint32_t button_index = usage - 1;
       if (button_index < Gamepad::kButtonsLengthCap) {
         associated.button_elements[button_index] = element;
         pad.buttons_length = std::max(pad.buttons_length, button_index + 1);
       }
     } else if (IOHIDElementGetType(element) == kIOHIDElementTypeInput_Misc) {
       uint32_t axis_index = usage - kAxisMinimumUsageNumber;
       if (axis_index < Gamepad::kAxesLengthCap) {
         associated.axis_elements[axis_index] = element;
         pad.axes_length = std::max(pad.axes_length, axis_index + 1);
       } else {
         mapped_all_axes = false;
       }
     }
   }

   if (!mapped_all_axes) {
     // For axes who's usage puts them outside the standard axesLengthCap range.
     uint32_t next_index = 0;
     for (id elem in elements) {
       IOHIDElementRef element = reinterpret_cast<IOHIDElementRef>(elem);
       if (!CheckCollection(element))
         continue;

       uint32_t usage_page = IOHIDElementGetUsagePage(element);
       uint32_t usage = IOHIDElementGetUsage(element);
       if (IOHIDElementGetType(element) == kIOHIDElementTypeInput_Misc &&
           usage - kAxisMinimumUsageNumber >= Gamepad::kAxesLengthCap &&
           usage_page <= kGameControlsUsagePage) {
         for (; next_index < Gamepad::kAxesLengthCap; ++next_index) {
           if (associated.axis_elements[next_index] == NULL)
             break;
         }
         if (next_index < Gamepad::kAxesLengthCap) {
           associated.axis_elements[next_index] = element;
           pad.axes_length = std::max(pad.axes_length, next_index + 1);
         }
       }

       if (next_index >= Gamepad::kAxesLengthCap)
         break;
     }
   }

   for (uint32_t axis_index = 0; axis_index < pad.axes_length; ++axis_index) {
     IOHIDElementRef element = associated.axis_elements[axis_index];
     if (element != NULL) {
       CFIndex axis_min = IOHIDElementGetLogicalMin(element);
       CFIndex axis_max = IOHIDElementGetLogicalMax(element);

       // Some HID axes report a logical range of -1 to 0 signed, which must be
       // interpreted as 0 to -1 unsigned for correct normalization behavior.
       if (axis_min == -1 && axis_max == 0) {
         axis_max = -1;
         axis_min = 0;
       }

       associated.axis_minimums[axis_index] = axis_min;
       associated.axis_maximums[axis_index] = axis_max;
       associated.axis_report_sizes[axis_index] =
           IOHIDElementGetReportSize(element);
     }
   }

   return (pad.axes_length > 0 || pad.buttons_length > 0);
 }

 size_t GamepadPlatformDataFetcherMac::GetEmptySlot() {
   // Find a free slot for this device.
   for (size_t slot = 0; slot < Gamepads::kItemsLengthCap; ++slot) {
     if (associated_[slot].device_ref == nullptr)
       return slot;
   }
   return Gamepads::kItemsLengthCap;
 }

 size_t GamepadPlatformDataFetcherMac::GetSlotForDevice(IOHIDDeviceRef device) {
   for (size_t slot = 0; slot < Gamepads::kItemsLengthCap; ++slot) {
     // If we already have this device, and it's already connected, don't do
     // anything now.
     if (associated_[slot].device_ref == device)
       return Gamepads::kItemsLengthCap;
   }
   return GetEmptySlot();
 }

 void GamepadPlatformDataFetcherMac::DeviceAdd(IOHIDDeviceRef device) {
   using base::mac::CFToNSCast;
   using base::mac::CFCastStrict;

   if (!enabled_)
     return;

   NSNumber* location_id = CFToNSCast(CFCastStrict<CFNumberRef>(
       IOHIDDeviceGetProperty(device, CFSTR(kIOHIDLocationIDKey))));
   int location_int = [location_id intValue];

   // Find an index for this device.
   size_t slot = GetSlotForDevice(device);

   // We can't handle this many connected devices.
   if (slot == Gamepads::kItemsLengthCap)
     return;

   // Clear some state that may have been left behind by previous gamepads
   memset(&associated_[slot], 0, sizeof(AssociatedData));

   PadState* state = GetPadState(location_int);
   if (!state)
     return;  // No available slot for this device

   NSNumber* vendor_id = CFToNSCast(CFCastStrict<CFNumberRef>(
       IOHIDDeviceGetProperty(device, CFSTR(kIOHIDVendorIDKey))));
   NSNumber* product_id = CFToNSCast(CFCastStrict<CFNumberRef>(
       IOHIDDeviceGetProperty(device, CFSTR(kIOHIDProductIDKey))));
   NSString* product = CFToNSCast(CFCastStrict<CFStringRef>(
       IOHIDDeviceGetProperty(device, CFSTR(kIOHIDProductKey))));
   int vendor_int = [vendor_id intValue];
   int product_int = [product_id intValue];

   char vendor_as_str[5], product_as_str[5];
   snprintf(vendor_as_str, sizeof(vendor_as_str), "%04x", vendor_int);
   snprintf(product_as_str, sizeof(product_as_str), "%04x", product_int);
   state->mapper =
       GetGamepadStandardMappingFunction(vendor_as_str, product_as_str);

   NSString* ident =
       [NSString stringWithFormat:@"%@ (%sVendor: %04x Product: %04x)", product,
                                  state->mapper ? "STANDARD GAMEPAD " : "",
                                  vendor_int, product_int];
   CopyNSStringAsUTF16LittleEndian(ident, state->data.id,
                                   sizeof(state->data.id));

   if (state->mapper) {
     CopyNSStringAsUTF16LittleEndian(@"standard", state->data.mapping,
                                     sizeof(state->data.mapping));
   } else {
     state->data.mapping[0] = 0;
   }

   base::ScopedCFTypeRef<CFArrayRef> elements(
       IOHIDDeviceCopyMatchingElements(device, NULL, kIOHIDOptionsTypeNone));

   if (!AddButtonsAndAxes(CFToNSCast(elements), state, slot))
     return;

   associated_[slot].location_id = location_int;
   associated_[slot].device_ref = device;
   state->data.connected = true;
 }

 void GamepadPlatformDataFetcherMac::DeviceRemove(IOHIDDeviceRef device) {
   if (!enabled_)
     return;

   // Find the index for this device.
   size_t slot;
   for (slot = 0; slot < Gamepads::kItemsLengthCap; ++slot) {
     if (associated_[slot].device_ref == device)
       break;
   }
   DCHECK(slot < Gamepads::kItemsLengthCap);
   // Leave associated device_ref so that it will be reconnected in the same
   // location. Simply mark it as disconnected.
   associated_[slot].location_id = 0;
   associated_[slot].device_ref = nullptr;
 }

 void GamepadPlatformDataFetcherMac::ValueChanged(IOHIDValueRef value) {
   if (!enabled_ || paused_)
     return;

   IOHIDElementRef element = IOHIDValueGetElement(value);
   IOHIDDeviceRef device = IOHIDElementGetDevice(element);

   // Find device slot.
   size_t slot;
   for (slot = 0; slot < Gamepads::kItemsLengthCap; ++slot) {
     if (associated_[slot].device_ref == device)
       break;
   }
   if (slot == Gamepads::kItemsLengthCap)
     return;

   PadState* state = GetPadState(associated_[slot].location_id);
   if (!state)
     return;

   Gamepad& pad = state->data;
   AssociatedData& associated = associated_[slot];

   uint32_t value_length = IOHIDValueGetLength(value);
   if (value_length > 4) {
     // Workaround for bizarre issue with PS3 controllers that try to return
     // massive (30+ byte) values and crash IOHIDValueGetIntegerValue
     return;
   }

   // Find and fill in the associated button event, if any.
   for (size_t i = 0; i < pad.buttons_length; ++i) {
     if (associated.button_elements[i] == element) {
       pad.buttons[i].pressed = IOHIDValueGetIntegerValue(value);
       pad.buttons[i].value = pad.buttons[i].pressed ? 1.f : 0.f;
       pad.timestamp = std::max(pad.timestamp, IOHIDValueGetTimeStamp(value));
       return;
     }
   }

   // Find and fill in the associated axis event, if any.
   for (size_t i = 0; i < pad.axes_length; ++i) {
     if (associated.axis_elements[i] == element) {
       CFIndex axis_min = associated.axis_minimums[i];
       CFIndex axis_max = associated.axis_maximums[i];
       CFIndex axis_value = IOHIDValueGetIntegerValue(value);

       if (axis_min > axis_max) {
         // We'll need to interpret this axis as unsigned during normalization.
         switch (associated.axis_report_sizes[i]) {
           case 8:
             pad.axes[i] = NormalizeUInt8Axis(axis_value, axis_min, axis_max);
             break;
           case 16:
             pad.axes[i] = NormalizeUInt16Axis(axis_value, axis_min, axis_max);
             break;
           case 32:
             pad.axes[i] = NormalizeUInt32Axis(axis_value, axis_min, axis_max);
             break;
         }
       } else {
         pad.axes[i] = NormalizeAxis(axis_value, axis_min, axis_max);
       }

       pad.timestamp = std::max(pad.timestamp, IOHIDValueGetTimeStamp(value));
       return;
     }
   }
 }

 void GamepadPlatformDataFetcherMac::GetGamepadData(bool) {
   if (!enabled_)
     return;

   // Loop through and GetPadState to indicate the devices are still connected.
   for (size_t slot = 0; slot < Gamepads::kItemsLengthCap; ++slot) {
     if (associated_[slot].device_ref != nullptr) {
       GetPadState(associated_[slot].location_id);
     }
   }
 }

 }  // namespace device
	// Copyright (c) 2012 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "device/gamepad/gamepad_platform_data_fetcher_mac.h"

	#include <stdint.h>
	#include <string.h>

	#include "base/mac/foundation_util.h"
	#include "base/mac/scoped_nsobject.h"
	#include "base/macros.h"
	#include "base/strings/string16.h"
	#include "base/strings/string_util.h"
	#include "base/strings/utf_string_conversions.h"
	#include "base/time/time.h"

	#import <Foundation/Foundation.h>
	#include <IOKit/hid/IOHIDKeys.h>

	namespace device {

	namespace {

	void CopyNSStringAsUTF16LittleEndian(NSString* src,
	UChar* dest,
	size_t dest_len) {
	NSData* as16 = [src dataUsingEncoding:NSUTF16LittleEndianStringEncoding];
	memset(dest, 0, dest_len);
	[as16 getBytes:dest length:dest_len - sizeof(UChar)];
	}

	NSDictionary* DeviceMatching(uint32_t usage_page, uint32_t usage) {
	return [NSDictionary
	dictionaryWithObjectsAndKeys:[NSNumber numberWithUnsignedInt:usage_page],
	base::mac::CFToNSCast(
	CFSTR(kIOHIDDeviceUsagePageKey)),
	[NSNumber numberWithUnsignedInt:usage],
	base::mac::CFToNSCast(
	CFSTR(kIOHIDDeviceUsageKey)),
	nil];
	}

	float NormalizeAxis(CFIndex value, CFIndex min, CFIndex max) {
	return (2.f * (value - min) / static_cast<float>(max - min)) - 1.f;
	}

	float NormalizeUInt8Axis(uint8_t value, uint8_t min, uint8_t max) {
	return (2.f * (value - min) / static_cast<float>(max - min)) - 1.f;
	}

	float NormalizeUInt16Axis(uint16_t value, uint16_t min, uint16_t max) {
	return (2.f * (value - min) / static_cast<float>(max - min)) - 1.f;
	}

	float NormalizeUInt32Axis(uint32_t value, uint32_t min, uint32_t max) {
	return (2.f * (value - min) / static_cast<float>(max - min)) - 1.f;
	}

	// http://www.usb.org/developers/hidpage
	const uint32_t kGenericDesktopUsagePage = 0x01;
	const uint32_t kGameControlsUsagePage = 0x05;
	const uint32_t kButtonUsagePage = 0x09;
	const uint32_t kJoystickUsageNumber = 0x04;
	const uint32_t kGameUsageNumber = 0x05;
	const uint32_t kMultiAxisUsageNumber = 0x08;
	const uint32_t kAxisMinimumUsageNumber = 0x30;

	} // namespace

	GamepadPlatformDataFetcherMac::GamepadPlatformDataFetcherMac()
	: enabled_(true), paused_(false) {
	memset(associated_, 0, sizeof(associated_));
	}

	GamepadSource GamepadPlatformDataFetcherMac::source() {
	return Factory::static_source();
	}

	void GamepadPlatformDataFetcherMac::OnAddedToProvider() {
	hid_manager_ref_.reset(
	IOHIDManagerCreate(kCFAllocatorDefault, kIOHIDOptionsTypeNone));
	if (CFGetTypeID(hid_manager_ref_) != IOHIDManagerGetTypeID()) {
	enabled_ = false;
	return;
	}

	base::scoped_nsobject<NSArray> criteria(
	[[NSArray alloc] initWithObjects:DeviceMatching(kGenericDesktopUsagePage,
	kJoystickUsageNumber),
	DeviceMatching(kGenericDesktopUsagePage,
	kGameUsageNumber),
	DeviceMatching(kGenericDesktopUsagePage,
	kMultiAxisUsageNumber),
	nil]);
	IOHIDManagerSetDeviceMatchingMultiple(hid_manager_ref_,
	base::mac::NSToCFCast(criteria));

	RegisterForNotifications();
	}

	void GamepadPlatformDataFetcherMac::RegisterForNotifications() {
	// Register for plug/unplug notifications.
	IOHIDManagerRegisterDeviceMatchingCallback(hid_manager_ref_,
	DeviceAddCallback, this);
	IOHIDManagerRegisterDeviceRemovalCallback(hid_manager_ref_,
	DeviceRemoveCallback, this);

	// Register for value change notifications.
	IOHIDManagerRegisterInputValueCallback(hid_manager_ref_, ValueChangedCallback,
	this);

	IOHIDManagerScheduleWithRunLoop(hid_manager_ref_, CFRunLoopGetMain(),
	kCFRunLoopDefaultMode);

	enabled_ = IOHIDManagerOpen(hid_manager_ref_, kIOHIDOptionsTypeNone) ==
	kIOReturnSuccess;
	}

	void GamepadPlatformDataFetcherMac::UnregisterFromNotifications() {
	IOHIDManagerUnscheduleFromRunLoop(hid_manager_ref_, CFRunLoopGetCurrent(),
	kCFRunLoopDefaultMode);
	IOHIDManagerClose(hid_manager_ref_, kIOHIDOptionsTypeNone);
	}

	void GamepadPlatformDataFetcherMac::PauseHint(bool pause) {
	paused_ = pause;
	}

	GamepadPlatformDataFetcherMac::~GamepadPlatformDataFetcherMac() {
	UnregisterFromNotifications();
	}

	GamepadPlatformDataFetcherMac*
	GamepadPlatformDataFetcherMac::InstanceFromContext(void* context) {
	return reinterpret_cast<GamepadPlatformDataFetcherMac*>(context);
	}

	void GamepadPlatformDataFetcherMac::DeviceAddCallback(void* context,
	IOReturn result,
	void* sender,
	IOHIDDeviceRef ref) {
	InstanceFromContext(context)->DeviceAdd(ref);
	}

	void GamepadPlatformDataFetcherMac::DeviceRemoveCallback(void* context,
	IOReturn result,
	void* sender,
	IOHIDDeviceRef ref) {
	InstanceFromContext(context)->DeviceRemove(ref);
	}

	void GamepadPlatformDataFetcherMac::ValueChangedCallback(void* context,
	IOReturn result,
	void* sender,
	IOHIDValueRef ref) {
	InstanceFromContext(context)->ValueChanged(ref);
	}

	bool GamepadPlatformDataFetcherMac::CheckCollection(IOHIDElementRef element) {
	// Check that a parent collection of this element matches one of the usage
	// numbers that we are looking for.
	while ((element = IOHIDElementGetParent(element)) != NULL) {
	uint32_t usage_page = IOHIDElementGetUsagePage(element);
	uint32_t usage = IOHIDElementGetUsage(element);
	if (usage_page == kGenericDesktopUsagePage) {
	if (usage == kJoystickUsageNumber \|\| usage == kGameUsageNumber \|\|
	usage == kMultiAxisUsageNumber) {
	return true;
	}
	}
	}
	return false;
	}

	bool GamepadPlatformDataFetcherMac::AddButtonsAndAxes(NSArray* elements,
	PadState* state,
	size_t slot) {
	Gamepad& pad = state->data;
	AssociatedData& associated = associated_[slot];

	pad.axes_length = 0;
	pad.buttons_length = 0;
	pad.timestamp = 0;
	memset(pad.axes, 0, sizeof(pad.axes));
	memset(pad.buttons, 0, sizeof(pad.buttons));

	bool mapped_all_axes = true;

	for (id elem in elements) {
	IOHIDElementRef element = reinterpret_cast<IOHIDElementRef>(elem);
	if (!CheckCollection(element))
	continue;

	uint32_t usage_page = IOHIDElementGetUsagePage(element);
	uint32_t usage = IOHIDElementGetUsage(element);
	if (IOHIDElementGetType(element) == kIOHIDElementTypeInput_Button &&
	usage_page == kButtonUsagePage) {
	uint32_t button_index = usage - 1;
	if (button_index < Gamepad::kButtonsLengthCap) {
	associated.button_elements[button_index] = element;
	pad.buttons_length = std::max(pad.buttons_length, button_index + 1);
	}
	} else if (IOHIDElementGetType(element) == kIOHIDElementTypeInput_Misc) {
	uint32_t axis_index = usage - kAxisMinimumUsageNumber;
	if (axis_index < Gamepad::kAxesLengthCap) {
	associated.axis_elements[axis_index] = element;
	pad.axes_length = std::max(pad.axes_length, axis_index + 1);
	} else {
	mapped_all_axes = false;
	}
	}
	}

	if (!mapped_all_axes) {
	// For axes who's usage puts them outside the standard axesLengthCap range.
	uint32_t next_index = 0;
	for (id elem in elements) {
	IOHIDElementRef element = reinterpret_cast<IOHIDElementRef>(elem);
	if (!CheckCollection(element))
	continue;

	uint32_t usage_page = IOHIDElementGetUsagePage(element);
	uint32_t usage = IOHIDElementGetUsage(element);
	if (IOHIDElementGetType(element) == kIOHIDElementTypeInput_Misc &&
	usage - kAxisMinimumUsageNumber >= Gamepad::kAxesLengthCap &&
	usage_page <= kGameControlsUsagePage) {
	for (; next_index < Gamepad::kAxesLengthCap; ++next_index) {
	if (associated.axis_elements[next_index] == NULL)
	break;
	}
	if (next_index < Gamepad::kAxesLengthCap) {
	associated.axis_elements[next_index] = element;
	pad.axes_length = std::max(pad.axes_length, next_index + 1);
	}
	}

	if (next_index >= Gamepad::kAxesLengthCap)
	break;
	}
	}

	for (uint32_t axis_index = 0; axis_index < pad.axes_length; ++axis_index) {
	IOHIDElementRef element = associated.axis_elements[axis_index];
	if (element != NULL) {
	CFIndex axis_min = IOHIDElementGetLogicalMin(element);
	CFIndex axis_max = IOHIDElementGetLogicalMax(element);

	// Some HID axes report a logical range of -1 to 0 signed, which must be
	// interpreted as 0 to -1 unsigned for correct normalization behavior.
	if (axis_min == -1 && axis_max == 0) {
	axis_max = -1;
	axis_min = 0;
	}

	associated.axis_minimums[axis_index] = axis_min;
	associated.axis_maximums[axis_index] = axis_max;
	associated.axis_report_sizes[axis_index] =
	IOHIDElementGetReportSize(element);
	}
	}

	return (pad.axes_length > 0 \|\| pad.buttons_length > 0);
	}

	size_t GamepadPlatformDataFetcherMac::GetEmptySlot() {
	// Find a free slot for this device.
	for (size_t slot = 0; slot < Gamepads::kItemsLengthCap; ++slot) {
	if (associated_[slot].device_ref == nullptr)
	return slot;
	}
	return Gamepads::kItemsLengthCap;
	}

	size_t GamepadPlatformDataFetcherMac::GetSlotForDevice(IOHIDDeviceRef device) {
	for (size_t slot = 0; slot < Gamepads::kItemsLengthCap; ++slot) {
	// If we already have this device, and it's already connected, don't do
	// anything now.
	if (associated_[slot].device_ref == device)
	return Gamepads::kItemsLengthCap;
	}
	return GetEmptySlot();
	}

	void GamepadPlatformDataFetcherMac::DeviceAdd(IOHIDDeviceRef device) {
	using base::mac::CFToNSCast;
	using base::mac::CFCastStrict;

	if (!enabled_)
	return;

	NSNumber* location_id = CFToNSCast(CFCastStrict<CFNumberRef>(
	IOHIDDeviceGetProperty(device, CFSTR(kIOHIDLocationIDKey))));
	int location_int = [location_id intValue];

	// Find an index for this device.
	size_t slot = GetSlotForDevice(device);

	// We can't handle this many connected devices.
	if (slot == Gamepads::kItemsLengthCap)
	return;

	// Clear some state that may have been left behind by previous gamepads
	memset(&associated_[slot], 0, sizeof(AssociatedData));

	PadState* state = GetPadState(location_int);
	if (!state)
	return; // No available slot for this device

	NSNumber* vendor_id = CFToNSCast(CFCastStrict<CFNumberRef>(
	IOHIDDeviceGetProperty(device, CFSTR(kIOHIDVendorIDKey))));
	NSNumber* product_id = CFToNSCast(CFCastStrict<CFNumberRef>(
	IOHIDDeviceGetProperty(device, CFSTR(kIOHIDProductIDKey))));
	NSString* product = CFToNSCast(CFCastStrict<CFStringRef>(
	IOHIDDeviceGetProperty(device, CFSTR(kIOHIDProductKey))));
	int vendor_int = [vendor_id intValue];
	int product_int = [product_id intValue];

	char vendor_as_str[5], product_as_str[5];
	snprintf(vendor_as_str, sizeof(vendor_as_str), "%04x", vendor_int);
	snprintf(product_as_str, sizeof(product_as_str), "%04x", product_int);
	state->mapper =
	GetGamepadStandardMappingFunction(vendor_as_str, product_as_str);

	NSString* ident =
	[NSString stringWithFormat:@"%@ (%sVendor: %04x Product: %04x)", product,
	state->mapper ? "STANDARD GAMEPAD " : "",
	vendor_int, product_int];
	CopyNSStringAsUTF16LittleEndian(ident, state->data.id,
	sizeof(state->data.id));

	if (state->mapper) {
	CopyNSStringAsUTF16LittleEndian(@"standard", state->data.mapping,
	sizeof(state->data.mapping));
	} else {
	state->data.mapping[0] = 0;
	}

	base::ScopedCFTypeRef<CFArrayRef> elements(
	IOHIDDeviceCopyMatchingElements(device, NULL, kIOHIDOptionsTypeNone));

	if (!AddButtonsAndAxes(CFToNSCast(elements), state, slot))
	return;

	associated_[slot].location_id = location_int;
	associated_[slot].device_ref = device;
	state->data.connected = true;
	}

	void GamepadPlatformDataFetcherMac::DeviceRemove(IOHIDDeviceRef device) {
	if (!enabled_)
	return;

	// Find the index for this device.
	size_t slot;
	for (slot = 0; slot < Gamepads::kItemsLengthCap; ++slot) {
	if (associated_[slot].device_ref == device)
	break;
	}
	DCHECK(slot < Gamepads::kItemsLengthCap);
	// Leave associated device_ref so that it will be reconnected in the same
	// location. Simply mark it as disconnected.
	associated_[slot].location_id = 0;
	associated_[slot].device_ref = nullptr;
	}

	void GamepadPlatformDataFetcherMac::ValueChanged(IOHIDValueRef value) {
	if (!enabled_ \|\| paused_)
	return;

	IOHIDElementRef element = IOHIDValueGetElement(value);
	IOHIDDeviceRef device = IOHIDElementGetDevice(element);

	// Find device slot.
	size_t slot;
	for (slot = 0; slot < Gamepads::kItemsLengthCap; ++slot) {
	if (associated_[slot].device_ref == device)
	break;
	}
	if (slot == Gamepads::kItemsLengthCap)
	return;

	PadState* state = GetPadState(associated_[slot].location_id);
	if (!state)
	return;

	Gamepad& pad = state->data;
	AssociatedData& associated = associated_[slot];

	uint32_t value_length = IOHIDValueGetLength(value);
	if (value_length > 4) {
	// Workaround for bizarre issue with PS3 controllers that try to return
	// massive (30+ byte) values and crash IOHIDValueGetIntegerValue
	return;
	}

	// Find and fill in the associated button event, if any.
	for (size_t i = 0; i < pad.buttons_length; ++i) {
	if (associated.button_elements[i] == element) {
	pad.buttons[i].pressed = IOHIDValueGetIntegerValue(value);
	pad.buttons[i].value = pad.buttons[i].pressed ? 1.f : 0.f;
	pad.timestamp = std::max(pad.timestamp, IOHIDValueGetTimeStamp(value));
	return;
	}
	}

	// Find and fill in the associated axis event, if any.
	for (size_t i = 0; i < pad.axes_length; ++i) {
	if (associated.axis_elements[i] == element) {
	CFIndex axis_min = associated.axis_minimums[i];
	CFIndex axis_max = associated.axis_maximums[i];
	CFIndex axis_value = IOHIDValueGetIntegerValue(value);

	if (axis_min > axis_max) {
	// We'll need to interpret this axis as unsigned during normalization.
	switch (associated.axis_report_sizes[i]) {
	case 8:
	pad.axes[i] = NormalizeUInt8Axis(axis_value, axis_min, axis_max);
	break;
	case 16:
	pad.axes[i] = NormalizeUInt16Axis(axis_value, axis_min, axis_max);
	break;
	case 32:
	pad.axes[i] = NormalizeUInt32Axis(axis_value, axis_min, axis_max);
	break;
	}
	} else {
	pad.axes[i] = NormalizeAxis(axis_value, axis_min, axis_max);
	}

	pad.timestamp = std::max(pad.timestamp, IOHIDValueGetTimeStamp(value));
	return;
	}
	}
	}

	void GamepadPlatformDataFetcherMac::GetGamepadData(bool) {
	if (!enabled_)
	return;

	// Loop through and GetPadState to indicate the devices are still connected.
	for (size_t slot = 0; slot < Gamepads::kItemsLengthCap; ++slot) {
	if (associated_[slot].device_ref != nullptr) {
	GetPadState(associated_[slot].location_id);
	}
	}
	}

	} // namespace device