Controlling Seed to multi langauge verification environment

To be perfectly honest I'm not really familiar with doing randomisation in C++ either, there's no need when e and SV have such powerful randomisation capabilities. From looking at the man page for rand() and srand(), it looks like you get the default seed of 1 every time you start the program, unless you re-seed it with srand. You only use srand() once to set the seed, thereafter you call rand() to get the next random number in the sequence.

Now, returning to your question about where to do the randomisation, I would recommend doing it all in your chosen verification language (SV or e) because as I said, you have tool-provided random stability, you get constraint-based randomisation and you get a debugger for the randomisation. In contrast in C/C++ you get no guarantee of random stability (depends on how you interact with the model), nothing but basic random integers, no constraint syntax and no debugger.

I would also question whether you "model" is truly a model (in the which case why is it doing ANY randomisation)? We normally refer to a model as something that mimics the behaviour of the DUT so that we can predict the RTL outputs. If you really meant a BFM or other stimulus generator then I can understand why you want randomisation, but again I'd suggest that you code as much as possible in e or SV so that all of your stimulus can be controlled in the normal UVM fashion, top-down and coordinated by sequences. If you have even one component in C++ doing its own thing and not directly controlled by UVM sequences, it'll be really hard to write tests and to debug.

To be perfectly honest I'm not really familiar with doing randomisation in C++ either, there's no need when e and SV have such powerful randomisation capabilities. From looking at the man page for rand() and srand(), it looks like you get the default seed of 1 every time you start the program, unless you re-seed it with srand. You only use srand() once to set the seed, thereafter you call rand() to get the next random number in the sequence.

Now, returning to your question about where to do the randomisation, I would recommend doing it all in your chosen verification language (SV or e) because as I said, you have tool-provided random stability, you get constraint-based randomisation and you get a debugger for the randomisation. In contrast in C/C++ you get no guarantee of random stability (depends on how you interact with the model), nothing but basic random integers, no constraint syntax and no debugger.

I would also question whether you "model" is truly a model (in the which case why is it doing ANY randomisation)? We normally refer to a model as something that mimics the behaviour of the DUT so that we can predict the RTL outputs. If you really meant a BFM or other stimulus generator then I can understand why you want randomisation, but again I'd suggest that you code as much as possible in e or SV so that all of your stimulus can be controlled in the normal UVM fashion, top-down and coordinated by sequences. If you have even one component in C++ doing its own thing and not directly controlled by UVM sequences, it'll be really hard to write tests and to debug.