sc_context.h

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  set forth in the SystemC Open Source License Version 2.4 (the "License");
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/*****************************************************************************

  sc_context.h - 

  Original Author: Martin Janssen, Synopsys, Inc.

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

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  MODIFICATION LOG - modifiers, enter your name, affiliation, date and
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// $Log: sc_context.h,v $
// Revision 1.1.1.1  2006/12/15 20:31:36  acg
// SystemC 2.2
//
// Revision 1.4  2006/03/21 00:00:31  acg
//   Andy Goodrich: changed name of sc_get_current_process_base() to be
//   sc_get_current_process_b() since its returning an sc_process_b instance.
//
// Revision 1.3  2006/01/13 18:53:57  acg
// Andy Goodrich: added $Log command so that CVS comments are reproduced in
// the source.
//

#ifndef SC_CONTEXT_H
#define SC_CONTEXT_H


#include "sysc/datatypes/fx/sc_fx_ids.h"
#include "sysc/kernel/sc_simcontext.h"
#include "sysc/utils/sc_hash.h"

namespace sc_core {
    class sc_process_b;
}

using sc_core::default_ptr_hash_fn;

namespace sc_dt
{

// classes defined in this module
class sc_without_context;
template <class T> class sc_global;
template <class T> class sc_context;


// ----------------------------------------------------------------------------
//  CLASS : sc_without_context
//
//  Empty class that is used for its type only.
// ----------------------------------------------------------------------------

class sc_without_context {};


// ----------------------------------------------------------------------------
//  TEMPLATE CLASS : sc_global
//
//  Template global variable class; singleton; co-routine safe.
// ----------------------------------------------------------------------------

template <class T>
class sc_global
{

    sc_global();

    void update();

public:

    static sc_global<T>* instance();

    const T*& value_ptr();

private:

    static sc_global<T>* m_instance;

    sc_core::sc_phash<const sc_core::sc_process_b*,const T*> m_map;
    const sc_core::sc_process_b*                             m_proc;
    const T*                                                    m_value_ptr;

};


// ----------------------------------------------------------------------------
//  ENUM : sc_context_begin
//
//  Enumeration of context begin options.
// ----------------------------------------------------------------------------

enum sc_context_begin
{
    SC_NOW,
    SC_LATER
};


// ----------------------------------------------------------------------------
//  CLASS : sc_context
//
//  Template context class; co-routine safe.
// ----------------------------------------------------------------------------

template <class T>
class sc_context
{
    sc_context( const sc_context<T>& );
    void* operator new( std::size_t );

public:

    explicit sc_context( const T&, sc_context_begin = SC_NOW );
    ~sc_context();

    void begin();
    void end();

    static const T& default_value();
    const T& value() const;

private:

    const T   m_value;
    const T*& m_def_value_ptr;
    const T*  m_old_value_ptr;
};


// IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

// ----------------------------------------------------------------------------
//  TEMPLATE CLASS : sc_global
//
//  Template global variable class; singleton; co-routine safe.
// ----------------------------------------------------------------------------

template <class T>
sc_global<T>* sc_global<T>::m_instance = 0;


template <class T>
inline
sc_global<T>::sc_global()
: m_proc( 
    reinterpret_cast<const sc_core::sc_process_b*>( -1 ) ), 
    m_value_ptr( 0 )
{}


template <class T>
inline
void
sc_global<T>::update()
{
    const sc_core::sc_process_b* p = sc_core::sc_get_current_process_b();
    if( p != m_proc )
    {
        const T* vp = m_map[p];
        if( vp == 0 )
        {
            vp = new T( sc_without_context() );
            m_map.insert( p, vp );
        }
        m_proc = p;
        m_value_ptr = vp;
    }
}


template <class T>
inline
sc_global<T>*
sc_global<T>::instance()
{
    if( m_instance == 0 )
    {
        m_instance = new sc_global<T>;
    }
    return m_instance;
}


template <class T>
inline
const T*&
sc_global<T>::value_ptr()
{
    update();
    return m_value_ptr;
}


// ----------------------------------------------------------------------------
//  CLASS : sc_context
//
//  Template context class; co-routine safe.
// ----------------------------------------------------------------------------

template <class T>
inline
sc_context<T>::sc_context( const sc_context<T>& )
: m_value(),
  m_def_value_ptr( sc_global<T>::instance()->value_ptr() ),
  m_old_value_ptr( 0 )
{
    // this constructor should never be called
    SC_REPORT_FATAL( sc_core::SC_ID_INTERNAL_ERROR_, "should never be called" );
}

template <class T>
inline
void*
sc_context<T>::operator new( std::size_t )
{
    // this method should never be called
    SC_REPORT_FATAL( sc_core::SC_ID_INTERNAL_ERROR_, "should never be called" );
    return (void*)0;
}


template <class T>
inline
sc_context<T>::sc_context( const T& value_, sc_context_begin begin )
: m_value( value_ ),
  m_def_value_ptr( sc_global<T>::instance()->value_ptr() ),
  m_old_value_ptr( 0 )
{
    if( begin == SC_NOW )
    {
    m_old_value_ptr = m_def_value_ptr;
    m_def_value_ptr = &m_value;
    }
}

template <class T>
inline
sc_context<T>::~sc_context()
{
    if( m_old_value_ptr != 0 )
    {
        m_def_value_ptr = m_old_value_ptr;
    m_old_value_ptr = 0;
    }
}


template <class T>
inline
void
sc_context<T>::begin()
{
    if( m_old_value_ptr == 0 )
    {
    m_old_value_ptr = m_def_value_ptr;
    m_def_value_ptr = &m_value;
    }
    else
    {
        SC_REPORT_ERROR( sc_core::SC_ID_CONTEXT_BEGIN_FAILED_, 0 );
    }
}

template <class T>
inline
void
sc_context<T>::end()
{
    if( m_old_value_ptr != 0 )
    {
        m_def_value_ptr = m_old_value_ptr;
    m_old_value_ptr = 0;
    }
    else
    {
        SC_REPORT_ERROR( sc_core::SC_ID_CONTEXT_END_FAILED_, 0 );
    }
}


template <class T>
inline
const T&
sc_context<T>::default_value()
{
    return *sc_global<T>::instance()->value_ptr();
}

template <class T>
inline
const T&
sc_context<T>::value() const
{
    return m_value;
}

} // namespace sc_dt


#endif

// Taf!

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