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Controlling Seed to multi langauge verification environment

jaichandra

Hi

   I working on a multi language environment (UVM + C++)for an IP verification. I am new to C++. We are using a C++ model in our verification environment. We are precompiling the C++ model and call the C++ model through A DPI function. srand() function is called to generate random value in C++ file. We can control seed to UVM with -seed or -svseed irun command line option. Does C++ also use seed to generate its variables. If it does how can we control seed from irun command line?

 - regards

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  • As far as I'm aware, srand() would not be modified / re-implemented by the simulator so you'll be getting the default seed (1) unless you explicitly seed srand() itself, as per "man srand". Note the caveats in the man page regarding the lack of thread safety and hence stability of the sequence generated.

    You should really consider generating all your random numbers in SV, certainly if you want any kind of constraint on the sequence you really do not want to be doing this in C++!

    If you have random generation in SV and in C++, it will be hard for you to ensure the random sequence is stable and repeatable for debugging, whereas in SV and UVM this would be taken care of for you.

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  • As far as I'm aware, srand() would not be modified / re-implemented by the simulator so you'll be getting the default seed (1) unless you explicitly seed srand() itself, as per "man srand". Note the caveats in the man page regarding the lack of thread safety and hence stability of the sequence generated.

    You should really consider generating all your random numbers in SV, certainly if you want any kind of constraint on the sequence you really do not want to be doing this in C++!

    If you have random generation in SV and in C++, it will be hard for you to ensure the random sequence is stable and repeatable for debugging, whereas in SV and UVM this would be taken care of for you.

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