better docs and vscode config

.vscode/settings.json

@@ -0,0 +1,4 @@
+{
+    "python.defaultInterpreterPath": "${workspaceFolder}/.venv/bin/python",
+    "python.analysis.extraPaths": ["${workspaceFolder}/kyupy/src"]
+}

README.md

@@ -13,7 +13,7 @@ This project uses [Nix](https://nixos.org) to manage reproducible programming en
 
 Run `nix develop` to enter a shell with all necessary software.
 
-If `nix` is not installed, follow this [guide](https://librelane.readthedocs.io/en/stable/installation/nix_installation/index.html). No need to clone `librelane` here, but it is good to set up the `extra-substituters` as described in the guide for using LibreLane in the future (for making layouts with SkyWater 130nm technology).
+If `nix` is not installed, follow this [guide](https://librelane.readthedocs.io/en/stable/installation/nix_installation/index.html). No need to clone `librelane` here, but it is good to set up the `extra-substituters` as described in the guide for using LibreLane for making layouts with SkyWater 130nm technology.
 
 ## Usage
 
@@ -25,3 +25,11 @@ make
 uv run jpeg_core_tb_run_plasma.py
 ```
 
+Load synthesized circuits and display statistics (example code):
+
+```
+uv run load_sky130_circuits.py
+```
+
+Works also outside a `nix develop` shell if [uv](https://docs.astral.sh/uv/) is installed on the base system. The script demonstrates how to obtain synthesized netlists via nix derivations [published in this github repository](https://github.com/s-holst/benchmark-circuits). These circuits along with layout and timings are built on-demand (using LibreLane) if not yet available in local nix store.
+

load_sky130_circuits.py

@@ -15,10 +15,11 @@ def path_for(circuit: str):
 def verilog_nl_path_for(circuit: str):
     return next(path_for(circuit).glob("*/nl/*.nl.v"))
 
-def main():
-    c = verilog.load(verilog_nl_path_for("picorv32-sky130"), tlib=SKY130)
+def print_circuit_stats(circuit: str):
+    print(circuit)
+    c = verilog.load(verilog_nl_path_for(circuit), tlib=SKY130)
     c.resolve_tlib_cells(SKY130)
     for kind, count in sorted(c.stats.items()): print(f'  {kind:10s} {count}')
 
 if __name__ == "__main__":
-    main()
+    print_circuit_stats("picorv32-sky130")