/*

    File:       SomeTasks.cp

    Contains:   Some Multi Processing Tasks and utility functions.

    Version:    1.0

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*/

#include "SomeTasks.h"

#include "HIObjectThreadController.h"

/*****************************************************

*

* SendEventToUI(kind, params, iterator, result) 

*

* Purpose:  Posts an event to the main thread which is handling the User Interface

*

* Inputs:   kind      - the kind of event (in this sample code: kEventUpdateThreadUI or kEventTerminateThread)

*           params    - a pointer to the task params

*           iterator  - the current value of the iteration index

*           result    - the current value of the variable being calculated, in this sample code: pi

*

*/

void SendEventToUI(UInt32 kind, GeneralTaskWorkParamsPtr params, double iterator, double result)

    {

    params->iterator = iterator;

    params->result = result;

    EventRef theEvent;

    CreateEvent(NULL, kEventClassHIObjectThreadController, kind, GetCurrentEventTime(), kEventAttributeUserEvent, &theEvent);

    SetEventParameter(theEvent, kEventParamPostTarget, typeEventTargetRef, sizeof(params->threadControllerTarget), &params->threadControllerTarget);

    PostEventToQueue(GetMainEventQueue(), theEvent, kEventPriorityStandard);

    ReleaseEvent(theEvent);

    }

// pi = 4 ( 1 - 1/3 + 1/5 - 1/7 + 1/9 - ...)   

OSStatus CalculatingPiUsingLeibnizSimpleTask(void *p)

    {

    LeibnizTaskWorkParamsPtr params = (LeibnizTaskWorkParamsPtr)p;

    Boolean sign = params->sign;

    double denominator = params->general.iterator;

    double result = params->general.result;

    double lastDenominator = denominator + kSTEndIteration;

    double lastUIChange = denominator + kSTUIIteration;

    Duration updateInterval = 200 * durationMillisecond;

    AbsoluteTime nextTime = AddDurationToAbsolute(updateInterval, UpTime());

    for (; denominator < lastDenominator; )

        {

        if (sign)

            result += 4.0/denominator;

        else

            result -= 4.0/denominator;

        sign = ! sign;

        denominator += 2.0;

        // we don't want to submerge the main thread with too many events

        // so we check first if it's a good time to send one.

        // we also don't want to call too many APIs checking so we first

        // test if we did enough iterations.

        if (denominator > lastUIChange)

            {

            lastUIChange = denominator + kSTUIIteration;

            AbsoluteTime newTime = UpTime();

            if (S64Compare(UnsignedWideToUInt64(nextTime), UnsignedWideToUInt64(newTime)) < 0)

                {

                SendEventToUI(kEventUpdateThreadUI, (GeneralTaskWorkParamsPtr)params, denominator, result);

                nextTime = AddDurationToAbsolute(updateInterval, newTime);

                }

            }

        }

    // iteration is finished, we send the appropriate event to the main thread.

    SendEventToUI(kEventTerminateThread, (GeneralTaskWorkParamsPtr)params, denominator, result);

    return noErr;

    }

void * SetUpLeibniz(void)

    {

    LeibnizTaskWorkParamsPtr params = (LeibnizTaskWorkParamsPtr)malloc(sizeof(LeibnizTaskWorkParams));

    params->sign = true;

    params->general.iterator = 1.0;

    params->general.result = 0.0;

    return params;

    }

void TermLeibniz(void * p)

    {

    free(p);

    }

// pi = 2 ( (2/1) * (2/3) * (4/3) * (4/5) * (6/5) * (6/7) * (...) )

OSStatus CalculatingPiUsingWallisSimpleTask(void *p)

    {

    WallisTaskWorkParamsPtr params = (WallisTaskWorkParamsPtr)p;

    double numerator = params->general.iterator;

    double denominator = params->denominator;

    double result = params->general.result;

    double lastNumerator = numerator + kSTEndIteration;

    double lastUIChange = numerator + kSTUIIteration;

    AbsoluteTime interval, newTime, lastTime = UpTime();

    for (; numerator < lastNumerator; )

        {

        result *= numerator;

        result /= denominator;

        denominator += 2.0;

        result *= numerator;

        result /= denominator;

        numerator += 2.0;

        // we don't want to submerge the main thread with too many events

        // so we check first if it's a good time to send one.

        // we also don't want to call too many APIs checking so we first

        // test if we did enough iterations.        

        if (numerator > lastUIChange)

            {

            lastUIChange = numerator + kSTUIIteration;

            newTime = UpTime();

            interval = SubAbsoluteFromAbsolute(newTime, lastTime);

            Duration duration = AbsoluteToDuration(interval) / -1000;

            if (duration > 200)

                {

                lastTime = newTime;

                SendEventToUI(kEventUpdateThreadUI, (GeneralTaskWorkParamsPtr)params, numerator, result);

                }

            }

        }

    // iteration is finished, we send the appropriate event to the main thread.

    SendEventToUI(kEventTerminateThread, (GeneralTaskWorkParamsPtr)params, numerator, result);

    return noErr;

    }

void * SetUpWallis(void)

    {

    WallisTaskWorkParamsPtr params = (WallisTaskWorkParamsPtr)malloc(sizeof(WallisTaskWorkParams));

    params->general.iterator = 2.0;

    params->denominator = 1.0;

    params->general.result = 2.0;

    return params;

    }

void TermWallis(void * p)

    {

    free(p);

    }