ext/systemc/src/sysc/communication/sc_writer_policy.h

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

  sc_writer_policy.h -- The sc_signal<T> writer policy definition

  Original Author: Philipp A: Hartmann, OFFIS

  CHANGE LOG IS AT THE END OF THE FILE
 *****************************************************************************/


#ifndef SC_WRITER_POLICY_H_INCLUDED_
#define SC_WRITER_POLICY_H_INCLUDED_

#if !defined(SC_DEFAULT_WRITER_POLICY)
#  if defined(SC_NO_WRITE_CHECK)
#    define SC_DEFAULT_WRITER_POLICY SC_UNCHECKED_WRITERS
#  else
#    define SC_DEFAULT_WRITER_POLICY SC_ONE_WRITER
#  endif
#endif

namespace sc_core {

class sc_object;
class sc_port_base;
extern
void
sc_signal_invalid_writer( sc_object* target, sc_object* first_writer,
                          sc_object* second_writer, bool check_delta );

// SIGNAL WRITING POLICIES
//
// Note: if you add a new policy to the enum below you will need to add
// an additional overload of sc_reset::reset_signal_is() for the sc_signal<bool>
// instance. That will require changes to sysc/kernel/sc_reset.cpp and 
// sysc/kernel/sc_reset.h

enum sc_writer_policy
{
  SC_ONE_WRITER        = 0, ///< unique writer (from a unique port)
  SC_MANY_WRITERS      = 1, ///< allow multiple writers (with different ports)
  SC_UNCHECKED_WRITERS = 3  ///< even allow delta cycle conflicts (non-standard)
};

// signal forward declaration
template< typename T, sc_writer_policy POL = SC_DEFAULT_WRITER_POLICY >
class sc_signal;

template< sc_writer_policy >
struct sc_writer_policy_check;

struct sc_writer_policy_nocheck_write
{
  bool check_write( sc_object* /* target */, bool /* value_changed */ )
    { return true; }
  void update(){}
};

struct sc_writer_policy_check_write
{
  bool check_write( sc_object* target, bool value_changed );
  void update(){}
protected:
  sc_writer_policy_check_write( bool check_delta = false )
    : m_check_delta( check_delta ), m_writer_p(NULL) {}
  const bool         m_check_delta;
  sc_object*         m_writer_p;
};

struct sc_writer_policy_check_delta
    : sc_writer_policy_check_write
{

  sc_writer_policy_check_delta()
    : sc_writer_policy_check_write(true) {}

  bool check_write( sc_object* target, bool value_changed )
  {
      if( value_changed )
          return sc_writer_policy_check_write::check_write( target, true );
      return true;
  }

  void update(){ m_writer_p = NULL; }
};

struct sc_writer_policy_nocheck_port
{
  bool check_port( sc_object*, sc_port_base*, bool )
    { return true; }
};

struct sc_writer_policy_check_port
{
  bool check_port( sc_object* target, sc_port_base* port, bool is_output );

protected:
  sc_writer_policy_check_port() : m_output(0) {}
  sc_port_base* m_output;
};

template<>
struct sc_writer_policy_check<SC_ONE_WRITER>
  : sc_writer_policy_check_port
  , sc_writer_policy_check_write
{};

template<>
struct sc_writer_policy_check<SC_MANY_WRITERS>
  : sc_writer_policy_nocheck_port
  , sc_writer_policy_check_delta
{};

template<>
struct sc_writer_policy_check<SC_UNCHECKED_WRITERS>
  : sc_writer_policy_nocheck_port
  , sc_writer_policy_nocheck_write
{};

} // namespace sc_core

#endif

// Taf!