examples/Base/IPC/Async/Fibonacci1/Fibonacci1.cpp

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Description:
Example wraps a console in an active object.
Calculates Fibonacci number as chosen by the user. Note that, in this
example, the calculation is done as part of the console active object's 
RunL() and can take a long time to complete. It also means that nothing
else can happen (including responding to keyboard events) until the 
calculation is complete.   
*/



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


LOCAL_D CConsoleBase* console;

_LIT(KTxtMainInstructions,"\n\nPress 'F' to start\n      'ESC' to exit.\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 CExampleScheduler : public CActiveScheduler
        {
public:
        void Error (TInt aError) const;
        void WaitForAnyRequest();
        void SetActiveObject(CActiveConsole* aActiveConsole);
private:
          // data members defined for this class
        CActiveConsole* iActiveConsole;
        };


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

class TFibonacciEngine
        {
public:
        void Calculate (TInt aTerms) ;

        TInt iResult ;
        } ;


//
// -----> CFibonacciApplication (definition)
//
// This class encapsulates the fibonacci calculation engine
//

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

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

          // service request
        void ProcessKeyPress(TChar aChar) ;

private:
        CConsoleBase* iConsole ;
        TFibonacciEngine iFibonacciEngine ;
        };


//
// -----> 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;
        }


// CFibonacciApplication 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 ;
                if (input == 'c') value = -1;
                }
        while (input != EKeyEnter && input != 'c') ;

        return value ;
        }


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

CFibonacciApplication::CFibonacciApplication(CConsoleBase* aConsole )
        : CActiveConsole(aConsole)
          // construct zero-priority active object
        {
        iConsole = aConsole ;
        __DECLARE_NAME(_S("CFibonacciApplication"));
        } 


CFibonacciApplication* CFibonacciApplication::NewLC(CConsoleBase* aConsole )
        {
        CFibonacciApplication* self=new (ELeave) CFibonacciApplication(aConsole);
        CleanupStack::PushL(self);
        self->ConstructL();
        return self;
        }


void CFibonacciApplication::ConstructL()
        {
          // Add to active scheduler
        CActiveScheduler::Add(this);
          // Make this the active object
        ((CExampleScheduler*)(CActiveScheduler::Current()))->SetActiveObject(this);
        }


void CFibonacciApplication::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"
          //   cancel any outstanding request
          //   issue a fibonacci request.
        if (aChar == 'f' || aChar == 'F') 
                {
                _LIT(KTxtStartingFibonacci,"\nStarting Fibonacci....  \n");
                _LIT(KTxtReturnTermNumber,"\nENTER selects number, and starts calculation\nUP    arrow increases num\nDOWN  arrow decreases num\nC     cancels\n\n");
                _LIT(KTxtCalculating,"\nCalculating...\n");
                _LIT(KFormat2,"\nResult : %u \n");
                _LIT(KTxtCancelled,"Cancelled");

                iConsole->Printf(KTxtStartingFibonacci);
                
                TInt iterations = GetValueFromKeyboard(5,1,2,46, KTxtReturnTermNumber, iConsole) ;
                if (iterations == -1)  // convenient if awkward but allows us to indicate a request to cancel.
                        {
                        iConsole->Printf(KTxtCancelled);
                        iConsole->Printf(KTxtMainInstructions);
                        return;
                        }

                iConsole->Printf(KTxtCalculating);
                iFibonacciEngine.Calculate(iterations);
                
                iConsole->Printf(KFormat2, iFibonacciEngine.iResult) ;
                iConsole->Printf(KTxtMainInstructions);
                return;
                }

       // any other key ignore
        _LIT(KTxtNotRecognised,"\nUnwanted key pressed");
        iConsole->Printf(KTxtNotRecognised);
        iConsole->Printf(KTxtMainInstructions);
        }

//
// -----> TFibonacciEngine (implementation)
//

void TFibonacciEngine::Calculate (TInt aTerms) 
        {
        TInt iterations = aTerms ;

        TInt currentTotal = 1 ;
        TInt previousTotal = 0 ;
        _LIT(KTxtTooManyIterations,"Too many iterations");
        __ASSERT_ALWAYS(iterations<47,User::Panic(KTxtTooManyIterations,iterations));

        // if limit not yet reached
        while (iterations-- > 0)        
                {
                // calculate next number in series
                TInt newTotal = currentTotal + previousTotal ;

                // update variables
                previousTotal = currentTotal ;
                currentTotal = newTotal ;

                // introduce a delay
                User::After(1000000) ;
                }  

        iResult = currentTotal ;

        } 


// 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(KTxtFibSingActObj,"Single Active Object");
        console=Console::NewL(KTxtFibSingActObj, 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
        CExampleScheduler*  exampleScheduler = new (ELeave) CExampleScheduler;

          // Push onto the cleanup stack
        CleanupStack::PushL(exampleScheduler);
         
          // Install as the active scheduler
        CActiveScheduler::Install(exampleScheduler);

          // Create CFibonacciApplication active object.
        CFibonacciApplication* fibonacci = CFibonacciApplication::NewLC(console);

          // issue initial request
        fibonacci->RequestCharacter() ;
                        
        // Main part of the program:
        //    wait loop that cycles until ActiveScheduler::Stop called
        CActiveScheduler::Start();

        // Remove from the cleanup stack and destroy:
        // 1. the CFibonacciApplication active object.
        // 2. exampleScheduler
        CleanupStack::PopAndDestroy(); 
        CleanupStack::PopAndDestroy(); 
        }

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