--reduce-vias is a last stage: each net that has vias is routed again on
its own with vias made eight times dearer, everything else held as fixed
copper (the window stage's board), and its new copper is kept only if the
net fails nothing new and has fewer vias; the nets with the most vias go
first, within a share of the routing's own time. --via-cost exposes the
search's layer-change price (default 10 grid steps). bench.py records
each run's via count and prints via totals per variant.
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.
A QFN placed at 45 degrees had no exit on the grid: every horizontal or
vertical step from a pin passes its neighbours inside clearance. A pin whose
pad is turned more than ten degrees off the grid axes now leaves along the
pad's own axis, away from the part, until an L from there to a grid cell
clears every other net's pad, then searches as usual. The slanted leg is
checked and stored as an exact slab (segment_slab), not its bounding box,
in the grid stub checks and in the exact engine.
Where pins leave side by side, a cell names only its first owner, so stubs
are also indexed per cell for every connection near them; the exact
stub-vs-stub check, trace entry and rip-up all consult that index. A pin
with an axis exit and no clear cell reports no way out instead of falling
back to a cell on another net's route. diagnose.py replays with the exits.
A circle pad was its bounding box in both the grid and the exact check, so a
4 mm mounting hole's square corners refused legal routes 0.8 mm clear of the
real copper. It is now a 16-sided polygon whose sides touch the circle, so
the router is never closer than KiCad measures. diagnose.py takes --seed.
Rotated oval pads were built from padded corners that are not in outline
order, so they fell back to their bounding box; neighbouring boxes of a
rotated socket overlap, and the grid's own-pad exemption opened the
overlap to the pin's net, which the exact check then refused. Pads are now
the convex hull of their corners, the exact tree checks a rotated pad
against that outline, and the grid blocks cells against the same outline.
A via reused by a second connection of its net left that connection with
no claim on the via's footprint, so ripping the first owner freed cells
around a via still on the board. Footprint cells now keep every claimant.
A net class wider than the default was searched as a default trace: its
spread was empty below half a cell, halos were circular while the exact
check compares boxes, and a rip-up route only counted what its centre
crossed. The spread now covers the extra width in whole cells, halos are
square, and rip-up victims include what the spread crosses.
bench/diagnose.py now routes with net-class widths and hole spacing, as
the CLI does.
Copies the board (stripping its tracks unless --keep), exports the DSN
through mckicad, routes, applies the session and runs DRC with zones
refilled, counting hole problems whatever their severity. FREEROUTE and
MCK choose the builds under test.
A route may not leave a cell inside a wire keepout as a wire, nor reach
a pin there by one: it changes layer instead, and the via goes in the
pad. A pin whose every stub enters a keepout is reached by a via only.
A structure keepout named rule_area... (mckicad names KiCad rule areas
so) is checked for overlap only, as KiCad's DRC does, with the free ends
of each wire tested for their round caps.
--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.
rejected by the exact check, unroutable even alone, walled in (a pin's
free region is closed off by other copper, with the nets that close it),
or congestion. The board state is the best pass's, rebuilt by replaying
its paths.
Runs every board with every variant under the same seeds and compares
them seed by seed, so a change is judged against the routing-order
noise rather than one lucky or unlucky run.
rsp2k