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Blocking and Eventing

A SystemC thread can block for a given amount of time using the wait function in the SystemC library (not the Posix namesake).

Waiting for an arbitrary boolean expression to hold is hard to implement on top of C++ owing to its compiled nature:

C++ does not have a reflection API that enables a user's expression to be re-evaluated by the event kernel.
Yet we still want a reasonably neat and efficient way of passing an uninterpreted function.
Original solution: the delayed evaluation class:

     waituntil(mycount.delayed() > 5 && !reset.delayed());

Poor user had to just insert the delayed keyword where needed and then ignore it when reading the code.

It was too unwieldly, now removed. So today (pre C++11) use the less-efficient:

     do { wait(10, SC_NS); }  while(!((mycount > 5 && !reset)));

Within SystenC, there is no direct equivalent to the continuous assignment of Veriog. But the `fully-supported' sensitivity list always @(*) or always_comb can be reproduced with an SC_METHOD if you manually list the supporting nets.

More-efficient performance gained by putting the continuous assignment behaviour in a method and remembering to call just after whenever the support is changed in other parts of the model.

Fortunately, for TLM designs, there will be very little continuous assignment needed (e.g. perhaps just for interrupt routing).