//---------------------------------------------------------------------------
//
//	File: Timer.m
//
//  Abstract: Simple performance timer utility toolkit 
// 			 
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//
//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#include <mach/mach.h>
#include <mach/mach_time.h>
#include <unistd.h>

//---------------------------------------------------------------------------

#import "PrefTimer.h"

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

static const double kNanosecondConvScale  = 0.000000001;

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

struct PrefTimerAttributes
{
	double  machTimebaseInfoRatio;
	double  lastPrintTime;
	double  framesPerSecond;
	long    framesSinceLastPrint;
};

typedef struct PrefTimerAttributes  PrefTimerAttributes;

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

@implementation PrefTimer

//---------------------------------------------------------------------------

- (void) initTimeBaseInfo
{
	kern_return_t err = KERN_SUCCESS;
	
	mach_timebase_info_data_t  timebaseInfo;

	timebaseInfo.numer = 0;
	timebaseInfo.denom = 0;
	
	err = mach_timebase_info(&timebaseInfo);
	
	// Check errors
	
	check(err == KERN_SUCCESS);
	
	if( err != KERN_SUCCESS )
	{
		NSLog( @">> ERROR[%ld]: Pref Timer - Getting mach timebase info!", err );
	} // if
	else
	{
		double numer = (double)timebaseInfo.numer;
		double denom = (double)timebaseInfo.denom;
		
		prefTimerAttribs->machTimebaseInfoRatio = kNanosecondConvScale * ( numer / denom );
	} // else
} // initTimeBaseInfo

//---------------------------------------------------------------------------

- (id) init
{
	self = [super init];
	
	if( self )
	{
		prefTimerAttribs = (PrefTimerAttributesRef)malloc(sizeof(PrefTimerAttributes));
		
		if ( prefTimerAttribs != NULL )
		{
			prefTimerAttribs->lastPrintTime        = 0.0;
			prefTimerAttribs->framesSinceLastPrint = 0.0;
			prefTimerAttribs->framesPerSecond      = 0;
			
			[self initTimeBaseInfo];
		} // if
		else
		{
			NSLog( @">> ERROR: Pref Timer - Failure Allocating Memory For Attributes!" );
		}  // else
	} // if
	
	return( self );
} // init

//---------------------------------------------------------------------------

- (void) dealloc
{
	if( prefTimerAttribs != NULL )
	{
		free( prefTimerAttribs );
		
		prefTimerAttribs = NULL;
	} // if
	
    [super dealloc];
} // dealloc

//---------------------------------------------------------------------------

- (double) machAbsoluteTime
{
	// Get Mach absolute time.

	double machTime = (double)mach_absolute_time();

	// Convert to seconds.
	
	double machTimeSec = prefTimerAttribs->machTimebaseInfoRatio * machTime;

	return( machTimeSec );
} // machAbsoluteTime

//---------------------------------------------------------------------------

- (double) perfTick
{
	double deltaTime   = 0.0;
	double currentTime = 0.0;
	
	prefTimerAttribs->framesSinceLastPrint++;
	
	currentTime = [self machAbsoluteTime];
	deltaTime   = currentTime - prefTimerAttribs->lastPrintTime;
	
	if( deltaTime > 1.0 ) 
	{
		prefTimerAttribs->framesPerSecond      = prefTimerAttribs->framesSinceLastPrint / deltaTime;
		prefTimerAttribs->lastPrintTime        = [self machAbsoluteTime];
		prefTimerAttribs->framesSinceLastPrint = 0;
	} // if
	
	return( prefTimerAttribs->framesPerSecond );
} // perfTick

//---------------------------------------------------------------------------

@end

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

