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  Licensed to Accellera Systems Initiative Inc. (Accellera) under one or
  more contributor license agreements.  See the NOTICE file distributed
  with this work for additional information regarding copyright ownership.
  Accellera licenses this file to you under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with the
  License.  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
  implied.  See the License for the specific language governing
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 *****************************************************************************/

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

  stepwise_simulation.cpp -- Test step-wise simulation

  Original Author: Philipp A. Hartmann, OFFIS, 2011-01-21

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

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

  MODIFICATION LOG - modifiers, enter your name, affiliation, date and
  changes you are making here.

      Name, Affiliation, Date:
  Description of Modification:

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

#include <systemc.h>

const int num_events = 2;
const sc_time delay( 10, SC_NS );

//#define EXPLICIT_DELTA // should not modify the trace
#define DELAYED_EVENTS

SC_MODULE(echo)
{
  sc_event ev[num_events];
  SC_CTOR(echo)
    : self_trigger(3)
  {
    SC_METHOD(do_print);
#   ifdef DELAYED_EVENTS
      dont_initialize();
#   endif
      for( int i=0; i<num_events; ++i )
        sensitive << ev[i];
  }

  void do_print()
  {
    std::cout << "`" << sc_get_current_process_handle().name()
              << "' triggered at " << sc_time_stamp()
              << " - delta: " << sc_delta_count()
              << std::endl;

    if( --self_trigger > 1 )
      next_trigger( delay/2 );
    else if( self_trigger == 1 )
      next_trigger( SC_ZERO_TIME );
    else
      self_trigger = 3;

  }
  int self_trigger;
};

void do_step( sc_time const & step )
{
    sc_dt::uint64 delta       = sc_delta_count();
    static bool   start_delta = ( delta == 0 ) && ( step == SC_ZERO_TIME );
    std::cout
       << " ----- running for "
       << ( ( step == SC_ZERO_TIME ) ? "delta" : step.to_string() )
       << std::endl;

    sc_time start = sc_time_stamp();
    if( step > SC_ZERO_TIME ) 
    {
      std::cout << "   --- No-op start (warning) - ";
      sc_start( step / 2, SC_EXIT_ON_STARVATION );
      sc_assert( start == sc_time_stamp() );

      sc_start( step / 2, SC_RUN_TO_TIME );
      sc_assert( start + step / 2 == sc_time_stamp() );

      sc_start( step / 2 ); // complete step
    }
    else
    {
      sc_start( SC_ZERO_TIME );
    }
    sc_assert( start + step == sc_time_stamp() );

    std::cout
       << "    -- stopped at - "
       << sc_time_stamp() << " - delta: " << sc_delta_count()
       << std::endl;

    // delta has only increased, when a delta has been run
    sc_assert( sc_delta_count()
                 == delta + ( !start_delta && step == SC_ZERO_TIME ) );
    start_delta = false;
}

int sc_main(int, char*[])
{
  sc_assert( !sc_pending_activity() );
  sc_assert( sc_time_to_pending_activity()
             == sc_max_time() - sc_time_stamp() );

  sc_signal<bool> toggle("toggle");
  echo dut("echo");

  // notify future events
  for( int i=0; i<num_events; ++i )
    dut.ev[i].notify( (i+1) * delay );

  sc_assert( sc_pending_activity_at_future_time() );
  sc_assert( sc_time_to_pending_activity() == delay );

  do_step( SC_ZERO_TIME ); // elaborate

  while( sc_pending_activity() )
  {
    sc_assert( sc_pending_activity_at_current_time()
               || sc_time_to_pending_activity() > SC_ZERO_TIME );

    sc_assert( sc_pending_activity_at_future_time()
               || sc_time_to_pending_activity() == SC_ZERO_TIME );

    // run single (time) step
    do_step( sc_time_to_pending_activity() );

#   ifdef EXPLICIT_DELTA
      // run remaining current deltas (optional)
      while( sc_pending_activity_at_current_time() ) {
        sc_assert( sc_time_to_pending_activity() == SC_ZERO_TIME );
        do_step( SC_ZERO_TIME );
      }
#   endif // EXPLICIT_DELTA
  }

  // force one empty evaluate (w/ non-empty update)
  toggle.write( !toggle.read() );
  sc_assert(  sc_pending_activity_at_current_time() );
  sc_start( SC_ZERO_TIME );

  sc_assert( !sc_pending_activity() );
  sc_assert( sc_time_to_pending_activity()
             == sc_max_time() - sc_time_stamp() );

  std::cout << "Success" << std::endl;
  return 0;
}