The custom constructor passes its arguments directly to the base class constructor. It then uses the Or1ksim library function, or1ksim_set_time_point to set an initial time point at the start of simulation. The first call to or1ksim_get_time_period will return the time since the ISS started.

The doTrans function (which is used for both read and write) is extended from the version used with Or1ksimExtSC to synchronize with the SystemC clock.

There are two components to the time taken in this model, the time taken by the Or1ksim ISS and the time taken in any peripherals. At the time of an upcall, the SystemC wrapper thread will not have yielded control since either initialization or the last upcall, when a time point was set in the ISS using or1ksim_set_time_point.

A call to or1ksim_get_time_period gives the time used by the ISS in this period. This is used as the argument to wait, allowing any other threads in the SystemC world to run until the calculated simulation time is reached.

  wait( sc_core::sc_time( or1ksim_get_time_period(), sc_core::SC_SEC ));
	  

At this time the blocking transport function of the simple initiator socket is called with the payload and specifying a zero time offset (since the call to wait means the thread is synchronized with the SystemC clock).

  sc_core::sc_time  delay = sc_core::SC_ZERO_TIME;
  dataBus->b_transport( trans, delay );
	  

On return, the delay parameter will have been updated with any additional delay due to the transaction—in this case an estimate of the number of cycles to read or write the relevant UART register. This delay represents the additional time modeled since this thread last called wait. The thread should wait for this time, to allow other threads to catch up.

However, since this is a synchronized model, the target (which is still part of this thread of control, just in a different object) will have already called wait to model the time taken to read or write. So in this case, delay will still be zero on return.

The read or write is now complete. A new time point is set with set_time_point before control is returned to the ISS. The ISS will start measuring time from this start point, ready for use in the next upcall.

  or1ksim_set_time_point();
	  

The utility getClockRate is a simple wrapper for the underlying Or1ksim library function (see Section 8.3.1). It will be used in the main program (see Section 8.6).

unsigned long int
Or1ksimSyncSC::getClockRate()
{
  return or1ksim_clock_rate();

}       // getClockRate()
	  

The definition of the Or1ksim ISS wrapper module class with synchronized timing, Or1ksimSyncSC may be found in sys-models/sync-soc/Or1ksimSyncSC.cpp in the distribution.