Additional ngspice and Spectre simulation support

[rohanku]

• Add support for additional simulator-specific flags
  • Using Spectre as an example, will need to modify Tran for transient simulation parameters and Options for simulator flags.
• Add support for additional analysis types
  • Add additional structs that follow the example of Tran. Will need to update Spectre's Input type and simulate_inputs function to invoke the necessary analyses correctly.
  • May need to modify the nutlex crate to parse different analysis types.
• Add support for additional simulation primitives
  • Add additional blocks, following the example of Vsource.

[kcaisley]

I'm working on this now. I see that you some refactoring in #347, moving Tran under the spectre::analysis module and adding the Montecarlo simulation type.

I'd like to create an Op DC operating point with support for variable sweeps, and add support for options like transient noise to the existing Tran under spectre::analysis::tran. Then, I will make a unit test creating some inverters, and simulating their jitter and DC transfer characteristic.

Regarding your point

Add support for additional simulation primitives

Does this essentially equate to extending the built-in "schema", as discussed here?

[rohanku]

Yes, that is correct. One thing to note, we are now using https://github.com/rahulk29/psfparser for parsing Spectre output (though we are still using nutlex for ngspice). If you are interested in working on Spectre, you will need to update the parser to parse additional analysis outputs.