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 /*

  * smslib.m

  * 

  * SMSLib Sudden Motion Sensor Access Library

  * Copyright (c) 2010 Suitable Systems

  * All rights reserved.

  * 

  * Developed by: Daniel Griscom

  *               Suitable Systems

  *               http://www.suitable.com

  * 

  * Permission is hereby granted, free of charge, to any person obtaining a

  * copy of this software and associated documentation files (the

  * "Software"), to deal with the Software without restriction, including

  * without limitation the rights to use, copy, modify, merge, publish,

  * distribute, sublicense, and/or sell copies of the Software, and to

  * permit persons to whom the Software is furnished to do so, subject to

  * the following conditions:

  * 

  * - Redistributions of source code must retain the above copyright notice,

  * this list of conditions and the following disclaimers.

  * 

  * - Redistributions in binary form must reproduce the above copyright

  * notice, this list of conditions and the following disclaimers in the

  * documentation and/or other materials provided with the distribution.

  * 

  * - Neither the names of Suitable Systems nor the names of its

  * contributors may be used to endorse or promote products derived from

  * this Software without specific prior written permission.

  * 

  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

  * IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR

  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,

  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

  * SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE SOFTWARE.

  *

  * For more information about SMSLib, see

  *		<http://www.suitable.com/tools/smslib.html>

  * or contact

  *		Daniel Griscom

  *		Suitable Systems

  *		1 Centre Street, Suite 204

  *		Wakefield, MA 01880

  *		(781) 665-0053

  *

  */

 #import <IOKit/IOKitLib.h>

 #import <sys/sysctl.h>

 #import <math.h>

 #import "smslib.h"

 #pragma mark Internal structures

 // Represents a single axis of a type of sensor.

 typedef struct axisStruct {

 	int enabled;				// Non-zero if axis is valid in this sensor

 	int index;					// Location in struct of first byte

 	int size;					// Number of bytes

 	float zerog;				// Value meaning "zero g"

 	float oneg;					// Change in value meaning "increase of one g"

 								// (can be negative if axis sensor reversed)

 } axisStruct;

 // Represents the configuration of a type of sensor.

 typedef struct sensorSpec {

 	const char *model;			// Prefix of model to be tested

 	const char *name;			// Name of device to be read

 	unsigned int function;		// Kernel function index

 	int recordSize;				// Size of record to be sent/received

 	axisStruct axes[3];			// Description of three axes (X, Y, Z)

 } sensorSpec;

 // Configuration of all known types of sensors. The configurations are

 // tried in order until one succeeds in returning data.

 // All default values are set here, but each axis' zerog and oneg values 

 // may be changed to saved (calibrated) values.

 //

 // These values came from SeisMaCalibrate calibration reports. In general I've

 // found the following:

 //	- All Intel-based SMSs have 250 counts per g, centered on 0, but the signs

 //		are different (and in one case two axes are swapped)

 //	- PowerBooks and iBooks all have sensors centered on 0, and reading

 //		50-53 steps per gravity (but with differing polarities!)

 //	- PowerBooks and iBooks of the same model all have the same axis polarities

 //	- PowerBook and iBook access methods are model- and OS version-specific

 //

 // So, the sequence of tests is:

 //	- Try model-specific access methods. Note that the test is for a match to the

 //		beginning of the model name, e.g. the record with model name "MacBook"

 //		matches computer models "MacBookPro1,2" and "MacBook1,1" (and ""

 //		matches any model).

 //	- If no model-specific record's access fails, then try each model-independent

 //		access method in order, stopping when one works.

 static const sensorSpec sensors[] = {

 	// ****** Model-dependent methods ******

 	// The PowerBook5,6 is one of the G4 models that seems to lose

 	// SMS access until the next reboot.

 	{"PowerBook5,6", "IOI2CMotionSensor", 21, 60, {

 			{1, 0, 1, 0,  51.5},

 			{1, 1, 1, 0, -51.5},

 			{1, 2, 1, 0, -51.5}

 		}

 	},

 	// The PowerBook5,7 is one of the G4 models that seems to lose

 	// SMS access until the next reboot.

 	{"PowerBook5,7", "IOI2CMotionSensor", 21, 60, {

 			{1, 0, 1, 0,  51.5},

 			{1, 1, 1, 0,  51.5},

 			{1, 2, 1, 0,  51.5}

 		}

 	},

 	// Access seems to be reliable on the PowerBook5,8

 	{"PowerBook5,8", "PMUMotionSensor", 21, 60, {

 			{1, 0, 1, 0, -51.5},

 			{1, 1, 1, 0,  51.5},

 			{1, 2, 1, 0, -51.5}

 		}

 	},

 	// Access seems to be reliable on the PowerBook5,9

 	{"PowerBook5,9", "PMUMotionSensor", 21, 60, {

 			{1, 0, 1, 0,  51.5},

 			{1, 1, 1, 0, -51.5},

 			{1, 2, 1, 0, -51.5}

 		}

 	},

 	// The PowerBook6,7 is one of the G4 models that seems to lose

 	// SMS access until the next reboot.

 	{"PowerBook6,7", "IOI2CMotionSensor", 21, 60, {

 			{1, 0, 1, 0,  51.5},

 			{1, 1, 1, 0,  51.5},

 			{1, 2, 1, 0,  51.5}

 		}

 	},

 	// The PowerBook6,8 is one of the G4 models that seems to lose

 	// SMS access until the next reboot.

 	{"PowerBook6,8", "IOI2CMotionSensor", 21, 60, {

 			{1, 0, 1, 0,  51.5},

 			{1, 1, 1, 0,  51.5},

 			{1, 2, 1, 0,  51.5}

 		}

 	},

 	// MacBook Pro Core 2 Duo 17". Note the reversed Y and Z axes.

 	{"MacBookPro2,1", "SMCMotionSensor", 5, 40, {

 			{1, 0, 2, 0,  251},

 			{1, 2, 2, 0, -251},

 			{1, 4, 2, 0, -251}

 		}

 	},

 	// MacBook Pro Core 2 Duo 15" AND 17" with LED backlight, introduced June '07.

 	// NOTE! The 17" machines have the signs of their X and Y axes reversed

 	// from this calibration, but there's no clear way to discriminate between

 	// the two machines.

 	{"MacBookPro3,1", "SMCMotionSensor", 5, 40, {

 			{1, 0, 2, 0, -251},

 			{1, 2, 2, 0,  251},

 			{1, 4, 2, 0, -251}

 		}

 	},

 	// ... specs?

 	{"MacBook5,2", "SMCMotionSensor", 5, 40, {

 			{1, 0, 2, 0, -251},

 			{1, 2, 2, 0,  251},

 			{1, 4, 2, 0, -251}

 		}

 	},

 	// ... specs?

 	{"MacBookPro5,1", "SMCMotionSensor", 5, 40, {

 			{1, 0, 2, 0, -251},

 			{1, 2, 2, 0, -251},

 			{1, 4, 2, 0,  251}

 		}

 	},

 	// ... specs?

 	{"MacBookPro5,2", "SMCMotionSensor", 5, 40, {

 			{1, 0, 2, 0, -251},

 			{1, 2, 2, 0, -251},

 			{1, 4, 2, 0,  251}

 		}

 	},

 	// This is speculative, based on a single user's report. Looks like the X and Y axes

 	// are swapped. This is true for no other known Appple laptop.

 	{"MacBookPro5,3", "SMCMotionSensor", 5, 40, {

 			{1, 2, 2, 0, -251},

 			{1, 0, 2, 0, -251},

 			{1, 4, 2, 0, -251}

 		}

 	},

 	// ... specs?

 	{"MacBookPro5,4", "SMCMotionSensor", 5, 40, {

 			{1, 0, 2, 0, -251},

 			{1, 2, 2, 0, -251},

 			{1, 4, 2, 0,  251}

 		}

 	},

 	// ****** Model-independent methods ******

 	// Seen once with PowerBook6,8 under system 10.3.9; I suspect

 	// other G4-based 10.3.* systems might use this

 	{"", "IOI2CMotionSensor", 24, 60, {

 			{1, 0, 1, 0, 51.5},

 			{1, 1, 1, 0, 51.5},

 			{1, 2, 1, 0, 51.5}

 		}

 	},

 	// PowerBook5,6 , PowerBook5,7 , PowerBook6,7 , PowerBook6,8

 	// under OS X 10.4.*

 	{"", "IOI2CMotionSensor", 21, 60, {

 			{1, 0, 1, 0, 51.5},

 			{1, 1, 1, 0, 51.5},

 			{1, 2, 1, 0, 51.5}

 		}

 	},

 	// PowerBook5,8 , PowerBook5,9 under OS X 10.4.*

 	{"", "PMUMotionSensor", 21, 60, {

 			// Each has two out of three gains negative, but it's different

 			// for the different models. So, this will be right in two out

 			// of three axis for either model.

 			{1, 0, 1,  0, -51.5},

 			{1, 1, 1, -6, -51.5},

 			{1, 2, 1,  0, -51.5}

 		}

 	},

 	// All MacBook, MacBookPro models. Hardware (at least on early MacBookPro 15")

 	// is Kionix KXM52-1050 three-axis accelerometer chip. Data is at

 	// http://kionix.com/Product-Index/product-index.htm. Specific MB and MBP models

 	// that use this are: 

 	//		MacBook1,1

 	//		MacBook2,1

 	//		MacBook3,1

 	//		MacBook4,1

 	//		MacBook5,1

 	//		MacBook6,1

 	//		MacBookAir1,1

 	//		MacBookPro1,1

 	//		MacBookPro1,2

 	//		MacBookPro4,1

 	//		MacBookPro5,5

 	{"", "SMCMotionSensor", 5, 40, {

 			{1, 0, 2, 0, 251},

 			{1, 2, 2, 0, 251},

 			{1, 4, 2, 0, 251}

 		}

 	}

 };

 #define SENSOR_COUNT (sizeof(sensors)/sizeof(sensorSpec))

 #pragma mark Internal prototypes

 static int getData(sms_acceleration *accel, int calibrated, id logObject, SEL logSelector);

 static float getAxis(int which, int calibrated);

 static int signExtend(int value, int size);

 static NSString *getModelName(void);

 static NSString *getOSVersion(void);

 static BOOL loadCalibration(void);

 static void storeCalibration(void);

 static void defaultCalibration(void);

 static void deleteCalibration(void);

 static int prefIntRead(NSString *prefName, BOOL *success);

 static void prefIntWrite(NSString *prefName, int prefValue);

 static float prefFloatRead(NSString *prefName, BOOL *success);

 static void prefFloatWrite(NSString *prefName, float prefValue);

 static void prefDelete(NSString *prefName);

 static void prefSynchronize(void);

 // static long getMicroseconds(void);

 float fakeData(NSTimeInterval time);

 #pragma mark Static variables

 static int debugging = NO;		// True if debugging (synthetic data)

 static io_connect_t connection;	// Connection for reading accel values

 static int running = NO;		// True if we successfully started

 static unsigned int sensorNum = 0;		// The current index into sensors[]

 static const char *serviceName;	// The name of the current service

 static char *iRecord, *oRecord;	// Pointers to read/write records for sensor

 static int recordSize;			// Size of read/write records

 static unsigned int function;	// Which kernel function should be used

 static float zeros[3];			// X, Y and Z zero calibration values

 static float onegs[3];			// X, Y and Z one-g calibration values

 #pragma mark Defines

 // Pattern for building axis letter from axis number

 #define INT_TO_AXIS(a) (a == 0 ? @"X" : a == 1 ? @"Y" : @"Z")

 // Name of configuration for given axis' zero (axis specified by integer)

 #define ZERO_NAME(a) [NSString stringWithFormat:@"%@-Axis-Zero", INT_TO_AXIS(a)]

 // Name of configuration for given axis' oneg (axis specified by integer)

 #define ONEG_NAME(a) [NSString stringWithFormat:@"%@-Axis-One-g", INT_TO_AXIS(a)]

 // Name of "Is calibrated" preference

 #define CALIBRATED_NAME (@"Calibrated")

 // Application domain for SeisMac library

 #define APP_ID ((CFStringRef)@"com.suitable.SeisMacLib")

 // These #defines make the accelStartup code a LOT easier to read.

 #undef LOG

 #define LOG(message) \

 	if (logObject) { \

 		[logObject performSelector:logSelector withObject:message]; \

 	}

 #define LOG_ARG(format, var1) \

 	if (logObject) { \

 		[logObject performSelector:logSelector \

 			withObject:[NSString stringWithFormat:format, var1]]; \

 	}

 #define LOG_2ARG(format, var1, var2) \

 	if (logObject) { \

 		[logObject performSelector:logSelector \

 			withObject:[NSString stringWithFormat:format, var1, var2]]; \

 	}

 #define LOG_3ARG(format, var1, var2, var3) \

 	if (logObject) { \

 		[logObject performSelector:logSelector \

 			withObject:[NSString stringWithFormat:format, var1, var2, var3]]; \

 	}

 #pragma mark Function definitions

 // This starts up the accelerometer code, trying each possible sensor

 // specification. Note that for logging purposes it

 // takes an object and a selector; the object's selector is then invoked

 // with a single NSString as argument giving progress messages. Example

 // logging method:

 //		- (void)logMessage: (NSString *)theString

 // which would be used in accelStartup's invocation thusly:

 //		result = accelStartup(self, @selector(logMessage:));

 // If the object is nil, then no logging is done. Sets calibation from built-in

 // value table. Returns ACCEL_SUCCESS for success, and other (negative)

 // values for various failures (returns value indicating result of

 // most successful trial).

 int smsStartup(id logObject, SEL logSelector) {

 	io_iterator_t iterator;

 	io_object_t device;

 	kern_return_t result;

 	sms_acceleration accel;

 	int failure_result = SMS_FAIL_MODEL;

 	running = NO;

 	debugging = NO;

 	NSString *modelName = getModelName();

 	LOG_ARG(@"Machine model: %@\n", modelName);

 	LOG_ARG(@"OS X version: %@\n", getOSVersion());

 	LOG_ARG(@"Accelerometer library version: %s\n", SMSLIB_VERSION);

 	for (sensorNum = 0; sensorNum < SENSOR_COUNT; sensorNum++) {

 		// Set up all specs for this type of sensor

 		serviceName = sensors[sensorNum].name;

 		recordSize = sensors[sensorNum].recordSize;

 		function = sensors[sensorNum].function;

 		LOG_3ARG(@"Trying service \"%s\" with selector %d and %d byte record:\n",

 				serviceName, function, recordSize);

 		NSString *targetName = [NSString stringWithCString:sensors[sensorNum].model

 												  encoding:NSMacOSRomanStringEncoding];

 		LOG_ARG(@"    Comparing model name to target \"%@\": ", targetName);

 		if ([targetName length] == 0 || [modelName hasPrefix:targetName]) {

 			LOG(@"success.\n");

 		} else {

 			LOG(@"failure.\n");

 			// Don't need to increment failure_result.

 			continue;

 		}

 		LOG(@"    Fetching dictionary for service: ");

 		CFMutableDictionaryRef dict = IOServiceMatching(serviceName);

 		if (dict) {

 			LOG(@"success.\n");

 		} else {

 			LOG(@"failure.\n");

 			if (failure_result < SMS_FAIL_DICTIONARY) {

 				failure_result = SMS_FAIL_DICTIONARY;

 			}

 			continue;

 		}

 		LOG(@"    Getting list of matching services: ");

 		result = IOServiceGetMatchingServices(kIOMasterPortDefault, 

 										 dict, 

 										 &iterator);

 		if (result == KERN_SUCCESS) {

 			LOG(@"success.\n");

 		} else {

 			LOG_ARG(@"failure, with return value 0x%x.\n", result);

 			if (failure_result < SMS_FAIL_LIST_SERVICES) {

 				failure_result = SMS_FAIL_LIST_SERVICES;

 			}

 			continue;

 		}

 		LOG(@"    Getting first device in list: ");

 		device = IOIteratorNext(iterator);	

 		if (device == 0) {

 			LOG(@"failure.\n");

 			if (failure_result < SMS_FAIL_NO_SERVICES) {

 				failure_result = SMS_FAIL_NO_SERVICES;

 			}

 			continue;

 		} else {

 			LOG(@"success.\n");

 			LOG(@"    Opening device: ");

 		}

 		result = IOServiceOpen(device, mach_task_self(), 0, &connection);

 		if (result != KERN_SUCCESS) {

 			LOG_ARG(@"failure, with return value 0x%x.\n", result);

 			IOObjectRelease(device);

 			if (failure_result < SMS_FAIL_OPENING) {

 				failure_result = SMS_FAIL_OPENING;

 			}

 			continue;

 		} else if (connection == 0) {

 			LOG_ARG(@"'success', but didn't get a connection (return value was: 0x%x).\n", result);

 			IOObjectRelease(device);

 			if (failure_result < SMS_FAIL_CONNECTION) {

 				failure_result = SMS_FAIL_CONNECTION;

 			}

 			continue;

 		} else {

 			IOObjectRelease(device);

 			LOG(@"success.\n");

 		}

 		LOG(@"    Testing device.\n");

 		defaultCalibration();

 		iRecord = (char*) malloc(recordSize);

 		oRecord = (char*) malloc(recordSize);

 		running = YES;

 		result = getData(&accel, true, logObject, logSelector);

 		running = NO;

 		if (result) {

 			LOG_ARG(@"    Failure testing device, with result 0x%x.\n", result);

 			free(iRecord);

 			iRecord = 0;

 			free(oRecord);

 			oRecord = 0;

 			if (failure_result < SMS_FAIL_ACCESS) {

 				failure_result = SMS_FAIL_ACCESS;

 			}

 			continue;

 		} else {

 			LOG(@"    Success testing device!\n");

 			running = YES;

 			return SMS_SUCCESS;

 		}

 	}

 	return failure_result;

 }

 // This starts up the library in debug mode, ignoring the actual hardware.

 // Returned data is in the form of 1Hz sine waves, with the X, Y and Z

 // axes 120 degrees out of phase; "calibrated" data has range +/- (1.0/5);

 // "uncalibrated" data has range +/- (256/5). X and Y axes centered on 0.0,

 // Z axes centered on 1 (calibrated) or 256 (uncalibrated). 

 // Don't use smsGetBufferLength or smsGetBufferData. Always returns SMS_SUCCESS.

 int smsDebugStartup(id logObject, SEL logSelector) {

 	LOG(@"Starting up in debug mode\n");

 	debugging = YES;

 	return SMS_SUCCESS;

 }

 // Returns the current calibration values.

 void smsGetCalibration(sms_calibration *calibrationRecord) {

 	int x;

 	for (x = 0; x < 3; x++) {

 		calibrationRecord->zeros[x] = (debugging ? 0 : zeros[x]);

 		calibrationRecord->onegs[x] = (debugging ? 256 : onegs[x]);

 	}

 }

 // Sets the calibration, but does NOT store it as a preference. If the argument

 // is nil then the current calibration is set from the built-in value table.

 void smsSetCalibration(sms_calibration *calibrationRecord) {

 	int x;

 	if (!debugging) {

 		if (calibrationRecord) {

 			for (x = 0; x < 3; x++) {

 				zeros[x] = calibrationRecord->zeros[x];

 				onegs[x] = calibrationRecord->onegs[x];

 			}

 		} else {

 			defaultCalibration();

 		}

 	}

 }

 // Stores the current calibration values as a stored preference.

 void smsStoreCalibration(void) {

 	if (!debugging)

 		storeCalibration();

 }

 // Loads the stored preference values into the current calibration.

 // Returns YES if successful.

 BOOL smsLoadCalibration(void) {

 	if (debugging) {

 		return YES;

 	} else if (loadCalibration()) {

 		return YES;

 	} else {

 		defaultCalibration();

 		return NO;

 	}

 }

 // Deletes any stored calibration, and then takes the current calibration values

 // from the built-in value table.

 void smsDeleteCalibration(void) {

 	if (!debugging) {

 		deleteCalibration();

 		defaultCalibration();

 	}

 }

 // Fills in the accel record with calibrated acceleration data. Takes

 // 1-2ms to return a value. Returns 0 if success, error number if failure.

 int smsGetData(sms_acceleration *accel) {

 	NSTimeInterval time;

 	if (debugging) {

 		usleep(1500);						// Usually takes 1-2 milliseconds

 		time = [NSDate timeIntervalSinceReferenceDate];

 		accel->x = fakeData(time)/5;

 		accel->y = fakeData(time - 1)/5;

 		accel->z = fakeData(time - 2)/5 + 1.0;

 		return true;

 	} else {

 		return getData(accel, true, nil, nil);

 	}

 }

 // Fills in the accel record with uncalibrated acceleration data.

 // Returns 0 if success, error number if failure.

 int smsGetUncalibratedData(sms_acceleration *accel) {

 	NSTimeInterval time;

 	if (debugging) {

 		usleep(1500);						// Usually takes 1-2 milliseconds

 		time = [NSDate timeIntervalSinceReferenceDate];

 		accel->x = fakeData(time) * 256 / 5;

 		accel->y = fakeData(time - 1) * 256 / 5;

 		accel->z = fakeData(time - 2) * 256 / 5 + 256;

 		return true;

 	} else {

 		return getData(accel, false, nil, nil);

 	}

 }

 // Returns the length of a raw block of data for the current type of sensor.

 int smsGetBufferLength(void) {

 	if (debugging) {

 		return 0;

 	} else if (running) {

 		return sensors[sensorNum].recordSize;

 	} else {

 		return 0;

 	}

 }

 // Takes a pointer to accelGetRawLength() bytes; sets those bytes

 // to return value from sensor. Make darn sure the buffer length is right!

 void smsGetBufferData(char *buffer) {

 	IOItemCount iSize = recordSize;

 	IOByteCount oSize = recordSize;

 	kern_return_t result;

 	if (debugging || running == NO) {

 		return;

 	}

 	memset(iRecord, 1, iSize);

 	memset(buffer, 0, oSize);

 #if __MAC_OS_X_VERSION_MIN_REQUIRED  >= 1050

 	const size_t InStructSize = recordSize;

 	size_t OutStructSize = recordSize;

 	result = IOConnectCallStructMethod(connection,

 						function,				// magic kernel function number

 						(const void *)iRecord,

 						InStructSize,

 						(void *)buffer,

 						&OutStructSize

 					);

 #else // __MAC_OS_X_VERSION_MIN_REQUIRED 1050

 	result = IOConnectMethodStructureIStructureO(connection,

 						function,				// magic kernel function number

 						iSize,

 						&oSize,

 						iRecord,

 						buffer

 					);

 #endif // __MAC_OS_X_VERSION_MIN_REQUIRED 1050

 	if (result != KERN_SUCCESS) {

 		running = NO;

 	}

 }

 // This returns an NSString describing the current calibration in

 // human-readable form. Also include a description of the machine.

 NSString *smsGetCalibrationDescription(void) {

 	BOOL success;

 	NSMutableString *s = [[NSMutableString alloc] init];

 	if (debugging) {

 		[s release];

 		return @"Debugging!";

 	}

 	[s appendString:@"---- SeisMac Calibration Record ----\n \n"];

 	[s appendFormat:@"Machine model: %@\n", 

 		getModelName()];

 	[s appendFormat:@"OS X build: %@\n", 

 		getOSVersion()];

 	[s appendFormat:@"SeisMacLib version %s, record %d\n \n", 

 		SMSLIB_VERSION, sensorNum];

 	[s appendFormat:@"Using service \"%s\", function index %d, size %d\n \n",

 		serviceName, function, recordSize];

 	if (prefIntRead(CALIBRATED_NAME, &success) && success) {

 		[s appendString:@"Calibration values (from calibration):\n"];

 	} else {

 		[s appendString:@"Calibration values (from defaults):\n"];

 	}

 	[s appendFormat:@"    X-Axis-Zero  = %.2f\n", zeros[0]];

 	[s appendFormat:@"    X-Axis-One-g = %.2f\n", onegs[0]];

 	[s appendFormat:@"    Y-Axis-Zero  = %.2f\n", zeros[1]];

 	[s appendFormat:@"    Y-Axis-One-g = %.2f\n", onegs[1]];

 	[s appendFormat:@"    Z-Axis-Zero  = %.2f\n", zeros[2]];

 	[s appendFormat:@"    Z-Axis-One-g = %.2f\n \n", onegs[2]];

 	[s appendString:@"---- End Record ----\n"];

 	return s;

 }

 // Shuts down the accelerometer.

 void smsShutdown(void) {

 	if (!debugging) {

 		running = NO;

 		if (iRecord) free(iRecord);

 		if (oRecord) free(oRecord);

 		IOServiceClose(connection);

 	}

 }

 #pragma mark Internal functions

 // Loads the current calibration from the stored preferences.

 // Returns true iff successful.

 BOOL loadCalibration(void) {

 	BOOL thisSuccess, allSuccess;

 	int x;

 	prefSynchronize();

 	if (prefIntRead(CALIBRATED_NAME, &thisSuccess) && thisSuccess) {

 		// Calibrated. Set all values from saved values.

 		allSuccess = YES;

 		for (x = 0; x < 3; x++) {

 			zeros[x] = prefFloatRead(ZERO_NAME(x), &thisSuccess);

 			allSuccess &= thisSuccess;

 			onegs[x] = prefFloatRead(ONEG_NAME(x), &thisSuccess);

 			allSuccess &= thisSuccess;

 		}

 		return allSuccess;

 	}

 	return NO;

 }

 // Stores the current calibration into the stored preferences.

 static void storeCalibration(void) {

 	int x;

 	prefIntWrite(CALIBRATED_NAME, 1);

 	for (x = 0; x < 3; x++) {

 		prefFloatWrite(ZERO_NAME(x), zeros[x]);

 		prefFloatWrite(ONEG_NAME(x), onegs[x]);

 	}	

 	prefSynchronize();

 }

 // Sets the calibration to its default values.

 void defaultCalibration(void) {

 	int x;

 	for (x = 0; x < 3; x++) {

 		zeros[x] = sensors[sensorNum].axes[x].zerog;

 		onegs[x] = sensors[sensorNum].axes[x].oneg;

 	}

 }

 // Deletes the stored preferences.

 static void deleteCalibration(void) {

 	int x;

 	prefDelete(CALIBRATED_NAME);

 	for (x = 0; x < 3; x++) {

 		prefDelete(ZERO_NAME(x));

 		prefDelete(ONEG_NAME(x));

 	}

 	prefSynchronize();

 }

 // Read a named floating point value from the stored preferences. Sets

 // the success boolean based on, you guessed it, whether it succeeds.

 static float prefFloatRead(NSString *prefName, BOOL *success) {

 	float result = 0.0f;

 	CFPropertyListRef ref = CFPreferencesCopyAppValue((CFStringRef)prefName, 

 													   APP_ID);

 	// If there isn't such a preference, fail

 	if (ref == NULL) {

 		*success = NO;

 		return result;

 	}

 	CFTypeID typeID = CFGetTypeID(ref);

 	// Is it a number?

 	if (typeID == CFNumberGetTypeID()) {

 		// Is it a floating point number?

 		if (CFNumberIsFloatType((CFNumberRef)ref)) {

 			// Yup: grab it.

 			*success = CFNumberGetValue((__CFNumber*)ref, kCFNumberFloat32Type, &result);

 		} else {

 			// Nope: grab as an integer, and convert to a float.

 			long num;

 			if (CFNumberGetValue((CFNumberRef)ref, kCFNumberLongType, &num)) {

 				result = num;

 				*success = YES;

 			} else {

 				*success = NO;

 			}

 		}

 	// Or is it a string (e.g. set by the command line "defaults" command)?

 	} else if (typeID == CFStringGetTypeID()) {

 		result = (float)CFStringGetDoubleValue((CFStringRef)ref);

 		*success = YES;

 	} else {

 		// Can't convert to a number: fail.

 		*success = NO;

 	}

 	CFRelease(ref);

 	return result;

 }

 // Writes a named floating point value to the stored preferences.

 static void prefFloatWrite(NSString *prefName, float prefValue) {

 	CFNumberRef cfFloat = CFNumberCreate(kCFAllocatorDefault,

 										 kCFNumberFloatType,

 										 &prefValue);

 	CFPreferencesSetAppValue((CFStringRef)prefName,

 							 cfFloat,

 							 APP_ID);

 	CFRelease(cfFloat);

 }

 // Reads a named integer value from the stored preferences.

 static int prefIntRead(NSString *prefName, BOOL *success) {

 	Boolean internalSuccess;

 	CFIndex result = CFPreferencesGetAppIntegerValue((CFStringRef)prefName,

 													 APP_ID, 

 													 &internalSuccess);

 	*success = internalSuccess;

 	return result;

 }

 // Writes a named integer value to the stored preferences.

 static void prefIntWrite(NSString *prefName, int prefValue) {

 	CFPreferencesSetAppValue((CFStringRef)prefName,

 							 (CFNumberRef)[NSNumber numberWithInt:prefValue],

 							 APP_ID);

 }

 // Deletes the named preference values.

 static void prefDelete(NSString *prefName) {

 		CFPreferencesSetAppValue((CFStringRef)prefName,

 								 NULL,

 								 APP_ID);

 }

 // Synchronizes the local preferences with the stored preferences.

 static void prefSynchronize(void) {

 	CFPreferencesAppSynchronize(APP_ID);

 }

 // Internal version of accelGetData, with logging

 int getData(sms_acceleration *accel, int calibrated, id logObject, SEL logSelector) {

 	IOItemCount iSize = recordSize;

 	IOByteCount oSize = recordSize;

 	kern_return_t result;

 	if (running == NO) {

 		return -1;

 	}

 	memset(iRecord, 1, iSize);

 	memset(oRecord, 0, oSize);

 	LOG_2ARG(@"    Querying device (%u, %d): ", 

 			 sensors[sensorNum].function, sensors[sensorNum].recordSize);

 #if __MAC_OS_X_VERSION_MIN_REQUIRED  >= 1050

 	const size_t InStructSize = recordSize;

 	size_t OutStructSize = recordSize;

 	result = IOConnectCallStructMethod(connection,

 						function,				// magic kernel function number

 						(const void *)iRecord,

 						InStructSize,

 						(void *)oRecord,

 						&OutStructSize

 					);

 #else // __MAC_OS_X_VERSION_MIN_REQUIRED 1050

 	result = IOConnectMethodStructureIStructureO(connection,

 						function,				// magic kernel function number

 						iSize,

 						&oSize,

 						iRecord,

 						oRecord

 					);

 #endif // __MAC_OS_X_VERSION_MIN_REQUIRED 1050

 	if (result != KERN_SUCCESS) {

 		LOG(@"failed.\n");

 		running = NO;

 		return result;

 	} else {

 		LOG(@"succeeded.\n");

 		accel->x = getAxis(0, calibrated);

 		accel->y = getAxis(1, calibrated);

 		accel->z = getAxis(2, calibrated);

 		return 0;

 	}

 }

 // Given the returned record, extracts the value of the given axis. If

 // calibrated, then zero G is 0.0, and one G is 1.0.

 float getAxis(int which, int calibrated) {

 	// Get various values (to make code cleaner)

 	int indx = sensors[sensorNum].axes[which].index;

 	int size = sensors[sensorNum].axes[which].size;

 	float zerog = zeros[which];

 	float oneg = onegs[which];

 	// Storage for value to be returned

 	int value = 0;

 	// Although the values in the returned record should have the proper

 	// endianness, we still have to get it into the proper end of value.

 #if (BYTE_ORDER == BIG_ENDIAN)

 	// On PowerPC processors

 	memcpy(((char *)&value) + (sizeof(int) - size), &oRecord[indx], size);

 #endif

 #if (BYTE_ORDER == LITTLE_ENDIAN)

 	// On Intel processors

 	memcpy(&value, &oRecord[indx], size);

 #endif

 	value = signExtend(value, size);

 	if (calibrated) {

 		// Scale and shift for zero.

 		return ((float)(value - zerog)) / oneg;

 	} else {

 		return value;

 	}

 }

 // Extends the sign, given the length of the value.

 int signExtend(int value, int size) {

 	// Extend sign

 	switch (size) {

 		case 1:

 			if (value & 0x00000080)

 				value |= 0xffffff00;

 			break;

 		case 2:

 			if (value & 0x00008000)

 				value |= 0xffff0000;

 			break;

 		case 3:

 			if (value & 0x00800000)

 				value |= 0xff000000;

 			break;

 	}

 	return value;

 }

 // Returns the model name of the computer (e.g. "MacBookPro1,1")

 NSString *getModelName(void) {

 	char model[32];

 	size_t len = sizeof(model);

 	int name[2] = {CTL_HW, HW_MODEL};

 	NSString *result;

 	if (sysctl(name, 2, &model, &len, NULL, 0) == 0) {

 		result = [NSString stringWithFormat:@"%s", model];

 	} else {

 		result = @"";

 	}

 	return result;

 }

 // Returns the current OS X version and build (e.g. "10.4.7 (build 8J2135a)")

 NSString *getOSVersion(void) {

 	NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:

 		@"/System/Library/CoreServices/SystemVersion.plist"];

 	NSString *versionString = [dict objectForKey:@"ProductVersion"];

 	NSString *buildString = [dict objectForKey:@"ProductBuildVersion"];

 	NSString *wholeString = [NSString stringWithFormat:@"%@ (build %@)", 

 		versionString, buildString];

 	return wholeString;

 }

 // Returns time within the current second in microseconds.

 // long getMicroseconds() {

 //	struct timeval t;

 //	gettimeofday(&t, 0);

 //	return t.tv_usec;

 //}

 // Returns fake data given the time. Range is +/-1.

 float fakeData(NSTimeInterval time) {

 	long secs = lround(floor(time));

 	int secsMod3 = secs % 3;

 	double angle = time * 10 * M_PI * 2;

 	double mag = exp(-(time - (secs - secsMod3)) * 2);

 	return sin(angle) * mag;

 }