Timed Transactions: Adding delays to TLM calls.

A TLM call does not interact with the SystemC kernel or advance time.

To study system performance, however, we must model the time taken by the real transaction over the bus or network-on chip (NoC).

We continue to use SystemC EDS kernel with its tnow variable defined by the head of the event queue.

Note: In SystemC, we can always print the kernel tnow with:

  cout << ``Time now is : `` << simcontext()->time_stamp() << `` \n'';

We want to minimise context SystemC thread context switches for good performance par so, ideally, only enter EDS kernel when inter-thread communication is needed.