Ryan Malloy
89c0481ccc
Implements a working autorouter and the Java-free replacement for the freerouting.jar step: dsn_text -> parse_dsn -> build_board -> route -> write_ses. GridRouter is a single-layer A* maze search over a uniform occupancy grid: a cell is blocked by another net's pad (inflated by clearance + half trace width) or a keepout; each net's ratsnest is connected pin to pin; a routed trace then blocks other nets. The cell path becomes a trace polyline whose endpoints are the exact pin locations. Board-unit paths are converted back to DSN units for the SES (wire (path ...)) scopes. This is an MVP, not a port of FreeRouting's expansion-room maze: free-space rooms, rip-up-and-retry, multi-layer via search, and shove are deferred (they raise quality/coverage, not the connectivity milestone). It reaches connectivity on boards whose nets route on one layer without crossing. Adds tests/dsn/fixtures/simple_2net.dsn (a guaranteed-routable 2-net board). Invariant tests: both nets route, the emitted SES parses, every trace stays on a valid layer and within the board outline, and every routed net's trace endpoints sit exactly on its two pads. An oracle-gated test asserts connectivity parity with the reference FreeRouting JAR on the simple board.
DSN test fixtures
Hand-crafted minimal Specctra DSN files, written to exercise the parser. They
are modeled on the real fixtures shipped in the upstream FreeRouting repo
(fixtures/empty_board.dsn and fixtures/SMD-routing-issue-demo.dsn) so the
grammar and formatting match what kicad-cli pcb export specctra-dsn and
FreeRouting itself produce, but they were typed fresh here (no upstream file is
copied into this tree).
empty_board.dsn— the smallest valid board: parser, resolution, unit, and a structure with two signal layers and apcbboundary path. Modeled on FreeRoutingfixtures/empty_board.dsn.smd_demo.dsn— a fuller board exercising every scope the parser handles: quoted board/padstack/image names,via, defaultrule(width + clearance with a(type smd_smd)pair), akeepout, padstacks (rect and circle pads), images with pins, placement withfront/rotation, nets withComp-Pinreferences, and aclasswithcircuit/use_viaand arule. Modeled on FreeRoutingfixtures/SMD-routing-issue-demo.dsn.