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examples/Base/IPC/Async/Fibonacci3/Fibonacci3.cpp

// Copyright (c) 1997-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// This component and the accompanying materials are made available
// under the terms of "Eclipse Public License v1.0"
// which accompanies this distribution, and is available
// at the URL "http://www.eclipse.org/legal/epl-v10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
// Example wraps a console in an active object and performs the 
// Fibonacci calculation as a background active object.
// The technique used is similar to, but not identical, to that used by CIdle, where
// the background active object is repeatedly called provided the other (higher priority)
// active objects are not ready to run. 
// Fibonacci Active Objects example
//

#include <e32cons.h>
#include <e32base.h>
#include <e32std.h>

//nclude <e32hal.h>


LOCAL_D CConsoleBase* console;

_LIT(KTxtMainInstructions,"\n\nPress 'F' to start\n      'ESC' to exit\n      'C' to cancel, anytime\n");

//
// -----> CActiveConsole (definition)
//
// An abstract class which provides the facility to issue key requests. 
//
class CActiveConsole : public CActive
        {
public:
          // Construction
        CActiveConsole(CConsoleBase* aConsole);
        void ConstructL();

          // Destruction
        ~CActiveConsole();

          // Issue request
        void RequestCharacter();
        
          // Cancel request.
          // Defined as pure virtual by CActive;
          // implementation provided by this class.
        void DoCancel();

          // Service completed request.
          // Defined as pure virtual by CActive;
          // implementation provided by this class,
        void RunL();

          // Called from RunL() - an implementation must be provided
          // by derived classes to handle the completed request
        virtual void ProcessKeyPress(TChar aChar) = 0; 
          
protected:
          // Data members defined by this class
        CConsoleBase* iConsole; // A console for reading from
        };


//
// -----> CExampleScheduler (definition)
//
class CActiveConsole;

class CExampleScheduler : public CActiveScheduler
        {
public:
        void Error (TInt aError) const;
        void WaitForAnyRequest();
        void SetActiveObject(CActiveConsole* aActiveConsole);
private:
          // data members defined for this class
        CActiveConsole* iActiveConsole;
        };



//
// -----> CFibonacciEngine (definition)
//
// This class provides the fibonacci calculation engine
//

class CFibonacciEngine : public CBase
        {
public:
        CFibonacciEngine() ;
        void StartCalculate (TInt aTerms) ;
        void StepCalculate () ;
        
        TUint iResult ;

        enum TEngineState {eInactive, eCalculating, eCompleted}   ;
        TEngineState iState ;

private:
        TUint iCurrentTotal ;
        TUint iPreviousTotal ;
        TInt iTermsLeftToDo ;
        } ;


//
// -----> CFibonacciApplication (definition)
//
// This class encapsulates the fibonacci thread that runs the fibonacci engine
//

class CFibonacciApplication : public CActive
        {
public:
        CFibonacciApplication(CConsoleBase* aConsole, CFibonacciEngine* aFibonacciEngine) ;
        ~CFibonacciApplication() ;

        void CalculateFibonacci(TInt aIterations) ;

private:
        void DoCancel() ;
        void RunL() ;

private:
        CConsoleBase* iConsole ;
        CFibonacciEngine* iFibonacciEngine ;
        } ;


//
// -----> CFibonacciKeyHandler (definition)
//
// This class encapsulates the fibonacci keyboard handler
//

class CFibonacciKeyHandler : public CActiveConsole
        {
public:
        CFibonacciKeyHandler(   CConsoleBase* aConsole, 
                                                        CFibonacciApplication* aApplication) ;
        void ConstructL();

          // Static construction
        static CFibonacciKeyHandler* NewLC(CConsoleBase* aConsole, CFibonacciApplication* aHandler) ;

          // service request
        void ProcessKeyPress(TChar aChar) ;

private:
        CConsoleBase* iConsole ;
        CFibonacciApplication* iApplication ;
        };


//
// -----> CActiveConsole (implementation)
//
CActiveConsole::CActiveConsole( CConsoleBase* aConsole) 
        : CActive(CActive::EPriorityUserInput)
          // Construct high-priority active object
        {
        iConsole = aConsole;
        __DECLARE_NAME(_S("CActiveConsole"));

        }

void CActiveConsole::ConstructL()
        {
          // Add to active scheduler
        CActiveScheduler::Add(this);
        }

CActiveConsole::~CActiveConsole()
        {
        // Make sure we're cancelled
        Cancel();
        }

void  CActiveConsole::DoCancel()
        {
        iConsole->ReadCancel();
        }

void  CActiveConsole::RunL()
        {
          // Handle completed request
        ProcessKeyPress(TChar(iConsole->KeyCode()));
        }

void CActiveConsole::RequestCharacter()
        {
          // A request is issued to the CConsoleBase to accept a
          // character from the keyboard.
        iConsole->Read(iStatus); 
        SetActive();
        }


//
// -----> CExampleScheduler (implementation)
//
void CExampleScheduler::Error(TInt aError) const
        {
        _LIT(KTxtSchedulerError,"CExampleScheduler - error");
        User::Panic(KTxtSchedulerError,aError);
        }


void CExampleScheduler::WaitForAnyRequest()
        {
        if (!(iActiveConsole->IsActive()))
                iActiveConsole->RequestCharacter();     
        CActiveScheduler::WaitForAnyRequest();
        }

void CExampleScheduler::SetActiveObject(CActiveConsole* aActiveConsole)
        {
        iActiveConsole = aActiveConsole;
        }



// CFibonacciKeyHandler support routine
//   uses up arrow & down arrow to change number, Enter to select

TInt GetValueFromKeyboard (TInt aInitial, TInt aStep, TInt lowerLimit, TInt upperLimit, const TDesC& aPrompt, CConsoleBase* aConsole)
        {
        TChar input ;
        TInt value = aInitial ;

        aConsole->Printf(aPrompt) ;
        do
                {
                aConsole->SetPos(0);
                _LIT(KFormat1,"%d  ");
                aConsole->Printf(KFormat1, value);
                input = aConsole->Getch() ;
                if (input == EKeyUpArrow && value < upperLimit) value = value + aStep ;
                if (input == EKeyDownArrow && value > lowerLimit) value = value - aStep ;
                }
        while (input != EKeyEnter) ;

        return value ;
        }


//
// -----> CFibonacciKeyHandler (implementation)
//

CFibonacciKeyHandler::CFibonacciKeyHandler(CConsoleBase* aConsole, CFibonacciApplication* aApplication)
        : CActiveConsole(aConsole)
          // construct zero-priority active object
        {
        iConsole = aConsole ;
        iApplication = aApplication ;

        __DECLARE_NAME(_S("CFibonacciApplication"));
          // Add to active scheduler
        CActiveScheduler::Add(this);
          // Make this the active object
        ((CExampleScheduler*)(CActiveScheduler::Current()))->SetActiveObject(this);
        } 


void CFibonacciKeyHandler::ProcessKeyPress(TChar aChar)
        {
          // if key is ESC, cancel any outstanding request & stop the scheduler
        if (aChar == EKeyEscape)
                {
                CActiveScheduler::Stop();
                return;
                }

          // If key is "f" or "F", issue a Fibonacci request if none is in progress
        if (aChar == 'f' || aChar == 'F') 
                {
                if (!(iApplication->IsActive()))
                        {
                        _LIT(KTxtReturnTermNumber,"\nENTER selects num\nUP    arrow increases num\nDOWN  arrow decreases num\n\n");
                        TInt iterations = GetValueFromKeyboard(5,1,2,46, KTxtReturnTermNumber, iConsole) ;
                        iApplication->CalculateFibonacci(iterations);
                        }
                else
                        {
                        _LIT(KTxtAlreadyInProgress,"[Already in progress]");
                        iConsole->Printf(KTxtAlreadyInProgress);
                        }
                return;
                }

      // If key is "c" or "C", cancel any outstanding request   
        if (aChar == 'c' || aChar == 'C')
                {
                _LIT(KTxtCancelFibonacci,"\nCancelling Fibonacci....  \n");
                iConsole->Printf(KTxtCancelFibonacci);
                iApplication->Cancel();
                iConsole->Printf(KTxtMainInstructions);
                return;
                }
        
        _LIT(KTxtNotRecognised,"\nUnwanted key pressed");
        iConsole->Printf(KTxtNotRecognised);
        iConsole->Printf(KTxtMainInstructions);
        }


//
// -----> CFibonacciApplication (implementation)
//

CFibonacciApplication::CFibonacciApplication(CConsoleBase* aConsole, CFibonacciEngine* aFibonacciEngine)
//
// Constructor
//
        : CActive(EPriorityStandard)
        {
        iConsole = aConsole ;
        iFibonacciEngine = aFibonacciEngine ;
        CActiveScheduler::Add(this);
        __DECLARE_NAME(_S("CFibonacciApplication"));
        };


// destructor
CFibonacciApplication::~CFibonacciApplication() 
        {
        // cancel any requests and tell server 
        Cancel() ;
        }


void CFibonacciApplication::DoCancel() 
        {
        // cancel the active object request 
        iFibonacciEngine->iState = CFibonacciEngine::eInactive ;
        }



// initiate a request
void CFibonacciApplication::CalculateFibonacci(TInt aIterations)
        {
        // initialize engine
        // no neeed to set iStatus to KRequestPending, as request completes below
        iFibonacciEngine->StartCalculate(aIterations) ;

        // schedule the request
        SetActive() ;

        // send signal that this request has completed
        TRequestStatus* status = &iStatus ;
        User::RequestComplete(status, KErrNone) ;
        }



void CFibonacciApplication::RunL() 
// implements a simple state engine: {eInactive, eCalculating, eCompleted}
        {
        if (iFibonacciEngine->iState == CFibonacciEngine::eInactive )
                {
                _LIT(KTxtEngineNotInitialized,"Engine not initialized");
                User::Panic(KTxtEngineNotInitialized, KErrNotReady) ;
                }
        else if (iFibonacciEngine->iState == CFibonacciEngine::eCalculating )
                {               
                // unnecessary - just provides feedback on progression of the calculation
                _LIT(KTxtDot,".");
                iConsole->Printf(KTxtDot) ;

                // no neeed to set iStatus to KRequestPending, as request completes below

                // request next step
                iFibonacciEngine->StepCalculate() ;

                // schedule request
                SetActive() ;

                // send signal that this request has completed
                TRequestStatus* status = &iStatus ;
                User::RequestComplete(status, KErrNone) ;
                }
        else if (iFibonacciEngine->iState == CFibonacciEngine::eCompleted )
                {
                // finished calculation: print result and reset state engine
                _LIT(KFormat2,"\n    Result : %u \n");  //not used
                iConsole->Printf(KFormat2, iFibonacciEngine->iResult) ; 
                iConsole->Printf(KTxtMainInstructions) ; 
                iFibonacciEngine->iState = CFibonacciEngine::eInactive ;
                }
        }



//
// -----> CFibonacciEngine (implementation)
//
CFibonacciEngine::CFibonacciEngine() 
        {
        iState = eInactive ;
        }


void CFibonacciEngine::StartCalculate (TInt aTerms) 
        {
        // initialise all internal variables to initial state
        iCurrentTotal = 1 ;
        iPreviousTotal = 0 ;
        iResult = 0 ;
        iTermsLeftToDo = aTerms + 1 ;   // first step completed in variable initialization
        iState = eCalculating ;
        }



void CFibonacciEngine::StepCalculate () 
        {

        // if full calculation not yet complete, but in progress (i.e. not cancelled)
        if (--iTermsLeftToDo > 0 && iState == eCalculating)     
                {
                // calculate next number in series
                TInt newTotal = iCurrentTotal + iPreviousTotal ;

                // update internal variables
                iPreviousTotal = iCurrentTotal ;
                iCurrentTotal = newTotal ;

                // introduce a delay to make us a long-running service
                User::After(1000000) ;

                // not necessary, but allows running total to be used during the calculation
                // (say for putting values into a chart or graph)
                iResult = iCurrentTotal ;
                }
        else if (iTermsLeftToDo <= 0)
                {
                // flag that calculation has finished and ensure final result is available
                iState = eCompleted ;
                iResult = iCurrentTotal ;
                }
        } 



// This section deals with initialisation and ensuring we have a console active

void doExampleL () ;

void SetupConsoleL();

GLDEF_C TInt E32Main()                          // main function called by E32
    {
        CTrapCleanup* cleanup=CTrapCleanup::New();              // get clean-up stack
        TRAPD(error,SetupConsoleL());                           // more initialization, then do example
        _LIT(KTxtFibonacciExampleError,"Fibonacci example error");
        __ASSERT_ALWAYS(!error,User::Panic(KTxtFibonacciExampleError,error));
        delete cleanup;                                         // destroy clean-up stack
        return 0;                                                                               // and return
    }

void SetupConsoleL()                             // initialize and call example code under cleanup stack
    {
        _LIT(KTxtFibActObjBackground,"Background Active Object");
        console=Console::NewL(KTxtFibActObjBackground, TSize(KConsFullScreen,KConsFullScreen));
        CleanupStack::PushL(console);
        console->Printf(KTxtMainInstructions) ;
        TRAPD(error, doExampleL());                                                     // perform example function
        if (error)
                {
                _LIT(KFormat3,"failed: leave code=%d");
                console->Printf(KFormat3, error);
                }
        _LIT(KTxtPressAnyKey,"[Press any key to exit]");
        console->Printf(KTxtPressAnyKey);
        console->Getch();                                                               // get and ignore character
        CleanupStack::PopAndDestroy();                                  // close console
    }


//
// Do the example
//
void doExampleL()
    {
          // Construct and install the active scheduler; push onto the cleanup stack
        CExampleScheduler*  exampleScheduler = new (ELeave) CExampleScheduler;
        CleanupStack::PushL(exampleScheduler);
         
          // Install as the active scheduler
        CActiveScheduler::Install(exampleScheduler);

        // Create CFibonacciEngine active object; push onto the cleanup stack
        CFibonacciEngine* fibEngine = new (ELeave) CFibonacciEngine ;
    CleanupStack::PushL(fibEngine);
    
          // Create CFibonacciApplication handler active object; push onto the cleanup stack
        CFibonacciApplication* fibApplication = new CFibonacciApplication(console, fibEngine);
    CleanupStack::PushL(fibApplication);

          // Create CFibonacciKeyHandler active object; push onto the cleanup stack
        CFibonacciKeyHandler* fibKeyHandler = new CFibonacciKeyHandler(console, fibApplication);
    CleanupStack::PushL(fibKeyHandler);

          // issue initial request
        fibKeyHandler->RequestCharacter() ;
                        
        // Main part of the program:
        //    wait loop that cycles until ActiveScheduler::Stop called
        CActiveScheduler::Start();
           
        // Remove items from the cleanup stack and destroy them
        CleanupStack::PopAndDestroy(4); 
        }

---

Copyright ©2010 Nokia Corporation and/or its subsidiary(-ies).
All rights reserved. Unless otherwise stated, these materials are provided under the terms of the Eclipse Public License v1.0.