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

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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); 
        }

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