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

//

//  File: PrefTimer.m

//

//  Abstract: Simple performance timer utility toolkit

//

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//

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

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

#import <mach/mach.h>

#import <mach/mach_time.h>

#import <unistd.h>

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

#import "PrefTimer.h"

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

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

static const double kPrefTimerMachScaleFactor  = 0.000000001;

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

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

struct PrefTimerData

{

    double  mnTimeBase;

    double  mnMarkTime;

    double  mnFPS;

    long    mnCounter;

};

typedef struct PrefTimerData  PrefTimerData;

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

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

@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[%d]: Pref Timer - Getting mach timebase info!", err );

    } // if

    else

    {

        double numer = (double)timebaseInfo.numer;

        double denom = (double)timebaseInfo.denom;

        mpPrefTimer->mnTimeBase = kPrefTimerMachScaleFactor * ( numer / denom );

    } // else

} // initTimeBaseInfo

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

- (id) init

{

    self = [super init];

    if( self )

    {

        mpPrefTimer = (PrefTimerDataRef)calloc(1, sizeof(PrefTimerData));

        if( mpPrefTimer != NULL )

        {

            [self initTimeBaseInfo];

        } // if

        else

        {

            NSLog( @">> ERROR: Pref Timer - Failure Allocating Memory For Attributes!" );

        }  // else

    } // if

    return( self );

} // init

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

+ (id) prefTimer

{

    return( [[[PrefTimer allocWithZone:[self zone]] init] autorelease] );

} // prefTimer

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

- (void) dealloc

{

    if( mpPrefTimer != NULL )

    {

        free( mpPrefTimer );

        mpPrefTimer = NULL;

    } // if

    [super dealloc];

} // dealloc

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

- (double) machAbsoluteTime

{

    // Get Mach absolute time.

    double machTime = (double)mach_absolute_time();

    // Convert to seconds.

    double machTimeSec = mpPrefTimer->mnTimeBase * machTime;

    return( machTimeSec );

} // machAbsoluteTime

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

- (double) perfTick

{

    double deltaTime   = 0.0;

    double currentTime = 0.0;

    mpPrefTimer->mnCounter++;

    currentTime = [self machAbsoluteTime];

    deltaTime   = currentTime - mpPrefTimer->mnMarkTime;

    if( deltaTime > 1.0 )

    {

        mpPrefTimer->mnFPS      = mpPrefTimer->mnCounter / deltaTime;

        mpPrefTimer->mnMarkTime = [self machAbsoluteTime];

        mpPrefTimer->mnCounter  = 0;

    } // if

    return( mpPrefTimer->mnFPS );

} // perfTick

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

@end

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

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