Ryan Malloy
3bf4f6bed2
Ports the read path of FreeRouting's io/specctra/parser package to a Java-free Python implementation: - tokenizer: S-expression lexer mirroring SpecctraFileDescription.flex (comments, quoted strings, the string_quote IGNORE_QUOTE directive, case-insensitive keywords, and hash-prefixed names) - sexp: nested S-expression tree builder - shapes: rect/circle/polygon/path plus area-with-holes scopes - model: typed dataclasses for layers, padstacks, images, placements, nets, net classes, rules, keepouts - reader: recursive-descent scope readers producing a DsnBoard, one _read_* function per FreeRouting read_scope method 46 pytest cases cover the tokenizer, tree, shapes, and end-to-end parsing against hand-crafted fixtures modeled on FreeRouting's own test DSN files. Parses 90 of 91 upstream fixtures (the one failure is a binary OLE file, not text DSN).
freeroute
A native Python PCB autorouter — a Java-free port of the FreeRouting engine.
Why
kicad-mcp currently autoroutes by shelling out to freerouting.jar, which
drags in a JVM dependency. freeroute reimplements the routing engine in
pure Python so the toolchain needs no Java at all.
The contract
The entire integration surface is two Specctra files:
board.dsn ──▶ freeroute ──▶ board.ses
(unrouted) (routed session: traces + vias)
kicad-cli already exports .dsn and imports .ses, so freeroute is a
drop-in replacement for the JAR step — nothing else in the pipeline changes.
Status
Pre-alpha. Under active development. See docs/PORTING_PLAN.md
for the architecture and porting roadmap.
Usage (target)
freeroute board.dsn -o board.ses
Development
uv sync
uv run pytest
uv run ruff check src/ tests/
License
GPL-3.0-or-later, matching the FreeRouting source it is ported from.