#!/usr/bin/env python3 import argparse import glob import os import re import subprocess import sys import tempfile from pathlib import Path def die(message: str, exit_code: int = 1) -> None: print(f"Error: {message}", file=sys.stderr) sys.exit(exit_code) def tcl_brace(value: str) -> str: """ Quote a value for Tcl using braces. This is sufficient for normal filesystem paths and cell names. """ return "{" + value.replace("\\", "\\\\").replace("}", "\\}") + "}" def slug(value: str) -> str: """ Make a filesystem-friendly tag. """ value = str(value) value = value.replace(".", "p") value = value.replace("-", "m") value = value.replace("+", "") value = value.replace("/", "_") value = re.sub(r"[^A-Za-z0-9_]+", "_", value) return value.strip("_") def resolve_magic_rc(pdk_root: str, pdk: str) -> Path: """ Resolve the Magic rcfile from PDK_ROOT and PDK. Expected Open PDKs layout: $PDK_ROOT/$PDK/libs.tech/magic/$PDK.magicrc """ pdk_root_path = Path(pdk_root).expanduser().resolve() candidates = [ pdk_root_path / pdk / "libs.tech" / "magic" / f"{pdk}.magicrc", # Fallback for cases where PDK_ROOT already points directly at the PDK dir. pdk_root_path / "libs.tech" / "magic" / f"{pdk}.magicrc", ] for candidate in candidates: if candidate.exists(): return candidate searched = "\n ".join(str(c) for c in candidates) die(f"Could not find Magic rcfile. Searched:\n {searched}") def find_magic_binary() -> str: if os.path.exists("/usr/local/bin/magic"): return "/usr/local/bin/magic" return "magic" def parse_args() -> argparse.Namespace: parser = argparse.ArgumentParser( description="Extract parasitic SPICE from a GDS using Magic." ) parser.add_argument( "gds_file", help="Input GDS file.", ) parser.add_argument( "--pdk-root", default=os.environ.get("PDK_ROOT"), help="PDK root directory. Defaults to $PDK_ROOT.", ) parser.add_argument( "--pdk", default=os.environ.get("PDK"), help="PDK name, for example sky130A or gf180mcuC. Defaults to $PDK.", ) parser.add_argument( "--cthresh", type=float, default=None, help=( "Optional ext2spice capacitance threshold. " "If omitted, Magic's default is used." ), ) parser.add_argument( "--subcircuit-top", action="store_true", help=( "Emit 'ext2spice subcircuit top on'. " "Default behavior is Magic's default, equivalent to off." ), ) parser.add_argument( "--hierarchy-off", action="store_true", help=( "Emit 'ext2spice hierarchy off'. " "Default behavior is Magic's default, equivalent to hierarchy on." ), ) return parser.parse_args() def main() -> None: args = parse_args() if not args.pdk_root: die("PDK_ROOT is not set. Set $PDK_ROOT or pass --pdk-root.") if not args.pdk: die("PDK is not set. Set $PDK or pass --pdk.") gds_file_abs = os.path.abspath(args.gds_file) if not os.path.exists(gds_file_abs): die(f"GDS file does not exist: {gds_file_abs}") basename = os.path.splitext(os.path.basename(args.gds_file))[0] out_dir = os.path.dirname(gds_file_abs) app_dir = os.getcwd() magic_rc = resolve_magic_rc(args.pdk_root, args.pdk) cthresh_tag = "cthresh_default" if args.cthresh is None else f"cthresh_{slug(f'{args.cthresh:g}')}" subckt_tag = "subckt_top_on" if args.subcircuit_top else "subckt_top_off" hier_tag = "hier_off" if args.hierarchy_off else "hier_on" pdk_tag = f"pdk_{slug(args.pdk)}" output_tag = "__".join([pdk_tag, cthresh_tag, subckt_tag, hier_tag]) final_spice_path = os.path.join(out_dir, f"{basename}_pex__{output_tag}.spice") with tempfile.TemporaryDirectory() as temp_dir: os.chdir(temp_dir) temp_gds = os.path.join(temp_dir, f"{basename}.gds") os.symlink(gds_file_abs, temp_gds) klayout_script = f""" import sys import os try: import klayout.db as kdb except ImportError: sys.path.insert(0, os.path.join({app_dir!r}, ".venv", "lib", "python3.12", "site-packages")) import klayout.db as kdb layout = kdb.Layout() layout.read({temp_gds!r}) top_cell = None for cell in layout.top_cells(): if not cell.name.startswith("$$$"): top_cell = cell break if top_cell is None: sys.exit(1) print(top_cell.name) """ klayout_py_path = os.path.join(temp_dir, "find_top.py") with open(klayout_py_path, "w") as f: f.write(klayout_script) try: top_cell = subprocess.check_output( ["uv", "run", "python", klayout_py_path], cwd=app_dir, text=True, ).strip().split("\n")[0] except Exception as e: die(f"Error finding top cell with KLayout: {e}") magic_commands = [ "drc off", f"gds read {tcl_brace(temp_gds)}", f"load {tcl_brace(top_cell)}", "select top cell", "port makeall", "ext2spice lvs", "ext2spice rthresh 0", "ext2spice merge conservative" "extresist simplify on", "extresist minres 100", "extresist threshold 1000", "extract do resistance", "extract all", "ext2spice extresist on", "ext2spice resistor tee on", ] if args.cthresh is not None: magic_commands.append(f"ext2spice cthresh {args.cthresh:g}") if args.subcircuit_top: magic_commands.append("ext2spice subcircuit top on") if args.hierarchy_off: magic_commands.append("ext2spice hierarchy off") magic_commands.extend( [ "ext2spice", "quit -noprompt", ] ) with open("magic_extract.tcl", "w") as f: f.write("\n".join(magic_commands) + "\n") env = os.environ.copy() env["PDK_ROOT"] = str(Path(args.pdk_root).expanduser().resolve()) env["PDK"] = args.pdk print(f"Using PDK_ROOT: {env['PDK_ROOT']}") print(f"Using PDK: {env['PDK']}") print(f"Using magicrc: {magic_rc}") print(f"Top cell: {top_cell}") print("Running Magic extraction...") magic_bin = find_magic_binary() result = subprocess.run( [ magic_bin, "-dnull", "-noconsole", "-rcfile", str(magic_rc), "magic_extract.tcl", ], env=env, ) if result.returncode != 0: die(f"Magic failed with exit code {result.returncode}") spice_files = glob.glob("*.spice") spice_path = f"{top_cell}.spice" if not os.path.exists(spice_path) and spice_files: spice_path = spice_files[0] if not os.path.exists(spice_path): die("Magic did not produce a SPICE file.") with open(spice_path, "r") as f: lines = f.readlines() with open(final_spice_path, "w") as f: f.writelines(lines) print(f"Done. Extracted SPICE file: {final_spice_path}") if __name__ == "__main__": main()