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.
After the exact engine, every net routed wholly inside a window around a
stuck connection's pins is ripped, the rest of the board is laid down as
fixed copper, and the window alone is routed again at --window-resolution
(default 4) with the stuck net and the ripped nets only. The result is kept
only if fewer connections are left unrouted; each round doubles the margin.
The grid and exact routers gain only_nets and bounds for it. Off by default.
A net's pin groups were joined as a chain in pin order, and each
connection had to end on one chosen pin. Groups are now paired by a
minimum spanning tree (Manhattan distance between their nearest pins), and
a connection may start or end on any copper its net has already routed on
that side (path cells, via cells on every layer; not walled cells, whose
via moves into the pad). Plane nets keep their drops to the plane.
A connection that tees onto another records it as an anchor. Ripping a
connection rips what hangs on it, transitively, inside the same rip-up
transaction, so rollback restores all of them. The exact engine gets the
connections in commit order with their anchors and drops a T whose anchor
it rejects. --no-tree restores the chain.
Every connection is routed N times on the empty board, where routes may
share cells at a price that doubles each round for every other net on a
cell, and a cell that stays shared gains history. The real routing then
pays that history on free cells, so the first routes stop taking the space
later routes (a fine-pitch part's escapes) have no way round. Off by
default.
The old history term never steered: it only accrued at rip-up fights,
after the first routes had claimed the contested space, and routed
connections are never revisited in later passes.
Over 8 net orders it left 25 to 30 fewer connections unrouted on the
dense sense boards and 16 to 18 fewer on two PCBench boards, and was
never clearly worse. KiCad DRC on the sense harness: 41 opens to 28.
The connections a rip-up route crosses are rerouted at once in free
space. If that leaves fewer connections routed than before, the new
route comes out and every displaced connection goes back on its old
path, with its rip count as it was. Even trades are kept.
--access-cost C makes a route pay C to pass where it would close another
pin's way out (its end cells, the via it may need there, and the
clearance around both) while that pin still has connections to route.
A pin inside a wire keepout can only leave by a via; its stub to the
cell centre was track inside the keepout, which the exact check refused.
The via now goes on the pin itself. Pin stubs are also checked exactly
against wire keepouts, as the exact engine will check them.
bench/diagnose.py reports what each refused connection collided with.
Each round routes every connection that has failed so far ahead of the
rest, which keep their order. The promoted set only grows, so two groups
cannot take turns failing; the best round is kept.
The router is deterministic, but its result depends heavily on which
connection routes first. A seed shuffles that order reproducibly, so a
change can be judged over several orders instead of the one it happened
to get.
Add the GPLv3 text (the package declared the licence but never shipped it),
a py.typed marker, and an sdist include/exclude allowlist so the distribution
carries only src/, docs/, README, LICENSE and pyproject. reference/ is a clone
of the GPL FreeRouting Java tree kept purely as a porting reference and must
never be redistributed inside this package; tests, caches and build output are
excluded too.
Switch to the PEP 639 SPDX licence expression with license-files, widen the
classifiers, and add an -o alias for -do. Rewrite the README around the engine
matrix: what each track and pass actually does, and what this is not (no
FreeRouting density parity on dense boards, and --diagonal is a recovery and
shortening pass, not a diagonal-native search).
The grid MVP was the only track reachable from the command line, so the
continuous room engine, channel packing, shove, and 45-degree routing were
unusable by anything shelling out to freeroute.
Add --engine {grid,exact,room} (default grid, unchanged behaviour) plus
--pack / --shove / --diagonal, and honour -mp on the tracks that implement
rip-up passes. Not every engine supports every pass; ENGINE_OPTIONS is the
matrix and an unsupported combination exits 2 with a message naming the
engines that do support the flag, rather than silently no-opping.
The pyproject declared a freeroute script but freeroute.cli was missing, so the
entry point was broken. Add it: reads a Specctra .dsn, routes (rip-up on by
default), writes SES. Accepts FreeRouting-compatible -de/-do flags so it can be
dropped in wherever 'java -jar freerouting.jar' was called.
rsp2k