RegisterState.hh

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/*
    Copyright (c) 2002-2009 Tampere University.
 
    This file is part of TTA-Based Codesign Environment (TCE).
 
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/**
 * @file RegisterState.hh
 *
 * Declaration of RegisterState class.
 *
 * @author Jussi Nykänen 2004 (nykanen-no.spam-cs.tut.fi)
 * @author Pekka Jääskeläinen 2005 (pjaaskel-no.spam-cs.tut.fi)
 * @note rating: red
 */
 
#ifndef TTA_REGISTER_STATE_HH
#define TTA_REGISTER_STATE_HH
 
#include <string>
 
#include "StateData.hh"
#include "SimValue.hh"
 
 
//////////////////////////////////////////////////////////////////////////////
// RegisterState
//////////////////////////////////////////////////////////////////////////////
 
/**
 * Class that represents the contents of a register.
 */
class RegisterState : public StateData {
public:
    RegisterState(int width, bool constantZero = false);
    RegisterState(SimValue& sharedRegister);
    virtual ~RegisterState();
    
    virtual void setValue(const SimValue& value);
    virtual const SimValue& value() const;
    
protected:
    /// Value of the RegisterState. @todo Fix this mutable mess.
    /// It's needed because OutputPortState needs to mask the value_ in
    /// its value() implementation.
    SimValue& value_;
 
private:
    /// Copying not allowed.
    RegisterState(const RegisterState&);
    /// Assignment not allowed.
    RegisterState& operator=(const RegisterState&);    
    /// Is the storage of this RegisterState shared with someone else?
    bool shared_;
    /// Is this register constant zero?
    bool constantZero_;
};
 
//////////////////////////////////////////////////////////////////////////////
// NullRegisterState
//////////////////////////////////////////////////////////////////////////////
 
/**
 * Models non-existing RegisterState.
 */
class NullRegisterState : public RegisterState {
public:
    static NullRegisterState& instance();
 
    virtual ~NullRegisterState();
    
    virtual void setValue(const SimValue& value);
    virtual const SimValue& value() const;
 
private:
    NullRegisterState();
    /// Copying not allowed.
    NullRegisterState(const NullRegisterState&);
    /// Assignment not allowed.
    NullRegisterState& operator=(const NullRegisterState&);
 
    /// Unique instance of NullRegisterState.
    static NullRegisterState* instance_;
};
 
#endif