Interactive simulation

[oscargus]

CXXRTL has defined a protocol for simulator-waveform viewer interaction: https://cxxrtl.org/protocol.html (the protocol and simulator seems to share the same name) and, e.g., Surfer, https://surfer-project.org/ , has some preliminary support for interacting with a simulator and showing the waveforms through it.

I believe that it would be really nice if NVC supports interactive simulation, one way or the other. I believe that from the Surfer side we can probably support other protocols as well, but CXXRTL will make it a bit simpler as there is some support already and one can avoid reinventing something else.

The main benefit is that you can start looking at your waveform early, even though your complete test bench may take a long time to simulate...

(Currently, there is no way defined to set signal values through CXXRTL, but that may of course also be a nice feature in the long run, to quickly simulate something without writing a test bench.)