rsp2k
a6aa1991a1
The router began as a port of FreeRouting and has grown its own engine (negotiated congestion, tree nets, exact checks, axis escapes), and 'freeroute' was one letter from the project it no longer follows. The package, module and command are now rpmroute; the freeroute command stays as an alias, and the RPMROUTE / RPMROUTE_ORACLE_JAVA variables fall back to the old FREEROUTE names. Version 2026.10.07. Routing is unchanged: a PCBench board routes to a byte-identical session either way.
61 lines
2.7 KiB
Markdown
61 lines
2.7 KiB
Markdown
# FreeRouting → Python porting plan
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> Seed document. The routing agent expands this after studying the upstream
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> Java source. Treat sections marked _(TBD from source study)_ as the first
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> research deliverable.
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## Ground truth: study the source
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Port from the **actual FreeRouting Java source**, not from the Specctra spec
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alone. The algorithm details (rip-up-and-retry ordering, cost functions,
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45°/free-angle geometry, autoroute vs. optimize passes) live in the code.
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```bash
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# Cloned into ./reference (gitignored — we don't vendor GPL source into history)
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git clone --depth 1 https://github.com/freerouting/freerouting reference/freerouting
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```
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Key upstream packages to map first (verify paths against the clone):
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- `app/freerouting/designforms/specctra/` — DSN/SES read/write. This is the
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I/O boundary we must match byte-compatibly enough for `kicad-cli` to import.
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- `app/freerouting/autoroute/` — the maze/rip-up router core.
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- `app/freerouting/board/` — the routing board data model (items, traces, vias,
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nets, clearance matrix).
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- `app/freerouting/geometry/planar/` — points, lines, tile shapes, the
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45°/free-angle geometry primitives.
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## The contract (fixed)
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Input: Specctra `.dsn`. Output: Specctra `.ses`. `kicad-cli pcb export
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specctra-dsn` produces the input; `kicad-cli pcb import specctra-ses` consumes
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the output. Match that I/O and the rest of `kicad-mcp` is unchanged.
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## Phased roadmap
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1. **DSN parser** — tokenize + parse the S-expression DSN into a typed board
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model (layers, components, padstacks, nets, keepouts, rules/clearances).
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First concrete, fully-testable module. Round-trip fixtures from `kicad-cli`.
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2. **SES writer** — emit a minimal valid session file KiCad imports cleanly,
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starting with an empty/no-op route to prove the I/O loop end to end.
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3. **Board model + geometry** — planar primitives and the item/net/clearance
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model the router operates on. _(TBD from source study.)_
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4. **Autorouter core** — maze routing with rip-up-and-retry. Start grid-based
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Manhattan/45° for an MVP; converge toward FreeRouting's approach. _(TBD.)_
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5. **Optimize pass** — via minimization, trace smoothing. _(TBD.)_
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6. **CLI + kicad-mcp integration** — `rpmroute board.dsn -o board.ses`, then
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swap it in behind `kicad_mcp/utils/freerouting_engine.py`'s JAR step.
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## Validation strategy
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For any `.dsn`, FreeRouting's JAR gives a reference `.ses`. Diff our output
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against it (connectivity first — every ratsnest resolved — then geometry).
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The JVM stays available as an oracle during development even though the
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shipped product has no Java dependency.
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## Conventions
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`uv` for everything, src-layout, ruff, pytest. Author: Ryan Malloy. Keep
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modules small and single-purpose. Tests alongside every parser/writer from
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the first commit.
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