#!/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", "extract do resistance", "extract all", "ext2sim labels on", "ext2sim", "extresist simplify off", "extresist 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()