Route wider net classes at their width, falling back where they don't fit

The grid is laid out for the default width; a wider trace also needs the
cells its extra half width reaches to be free, and claims a wider halo.
A connection that does not fit at its class width (typically at a
fine-pitch pin) is routed at the default instead and reported. A net is
written at its class width when all of its connections went in at it,
and the exact check verifies it at that width; nets that shove or the
diagonal pass reshaped go out at the default.

src/freeroute/cli.py

@@ -287,6 +287,14 @@ def main(argv: list[str] | None = None) -> int:
         print(f"freeroute: {len(missing)} connection(s) not routed:", file=sys.stderr)
         for net, a, b, _zone in missing:
             print(f"  {net}: {a} to {b}", file=sys.stderr)
+    if result.narrowed:
+        print(
+            f"freeroute: {len(result.narrowed)} connection(s) of a wider net class only fitted "
+            "at the default width; their nets are written at the default width:",
+            file=sys.stderr,
+        )
+        for net, a, b in result.narrowed:
+            print(f"  {net}: {a} to {b}", file=sys.stderr)
     if in_zone:
         print(
             f"freeroute: {len(in_zone)} more connection(s) left to a zone fill that may join them:",

src/freeroute/route/exact_router.py

@@ -99,6 +99,7 @@ def route_board_exact(
     route_first: frozenset | None = None,
     access_cost: float = 0.0,
     rollback: bool = True,
+    net_widths: dict[int, int] | None = None,
 ) -> ExactRouteResult:
     """Route ``board`` orthogonally and verify the result with exact geometry.
 
@@ -131,6 +132,7 @@ def route_board_exact(
         route_first=route_first,
         access_cost=access_cost,
         rollback=rollback,
+        net_widths=net_widths,
     )
     edge = 0 if edge_clearance is None else edge_clearance
     outline = board.outline
@@ -177,18 +179,22 @@ def route_board_exact(
     # 25-pin supply net costs that one connection, not the whole net.
     rejected: list[tuple[int, str, str]] = []
     ends_list = result.connection_ends or [("?", "?", "")] * len(result.connections)
+    # each net is checked at the width it will be written at: its class's
+    # when all of its connections went in at that, else the default
+    net_half = dict(result.net_half)
     for (net_no, wires, vias), ends in sorted(
         zip(result.connections, ends_list, strict=False), key=lambda c: c[0][0]
     ):
-        boxes = _copper_boxes(wires, vias, half_width, via_layers, via_half)
+        wire_half = net_half.get(net_no, half_width)
-        wire_count = len(_copper_boxes(wires, [], half_width, via_layers, via_half))
+        boxes = _copper_boxes(wires, vias, wire_half, via_layers, via_half)
+        wire_count = len(_copper_boxes(wires, [], wire_half, via_layers, via_half))
         if any(
             tree.clearance_conflict(
                 box, net_no, layer, clearance, "wire" if i < wire_count else "via"
             )
             for i, (box, box_layers) in enumerate(boxes)
             for layer in box_layers
-        ) or _end_in_rule_area(tree, wires, half_width) or (
+        ) or _end_in_rule_area(tree, wires, wire_half) or (
             outline is not None and not all(outline.box_clear(b, edge) for b, _ in boxes)
         ):
             rejected.append((net_no, *ends))
@@ -247,6 +253,17 @@ def route_board_exact(
     for net_no, acc in accepted.items():
         clean.wires[net_no] = acc.wires
         clean.vias[net_no] = acc.vias
+    # shove and the diagonal pass lay copper at the default width: nets they
+    # recovered, and nets whose traces shove pushed aside
+    reshaped = (set(accepted) - accepted_before_recovery) | {
+        net for net, acc in accepted.items() if acc.shove_count
+    }
+    if diagonal:
+        reshaped = set(accepted)
+    clean.net_half = {
+        net: half for net, half in net_half.items() if net in accepted and net not in reshaped
+    }
+    clean.narrowed = list(result.narrowed)
 
     drc_clean = tree.has_violation(clearance) is None
     return ExactRouteResult(result=clean, tree=tree, drc_clean=drc_clean, shoves=shoves)

src/freeroute/route/grid_router.py

@@ -61,7 +61,10 @@ class RouteResult:
     ``routed_net_numbers`` are the nets that got any wire or via.
     """
 
-    __slots__ = ("wires", "vias", "half_width", "unrouted", "connections", "connection_ends", "failed")
+    __slots__ = (
+        "wires", "vias", "half_width", "unrouted", "connections", "connection_ends", "failed",
+        "net_half", "narrowed",
+    )
 
     def __init__(self, half_width: int) -> None:
         self.wires: dict[int, list[tuple[int, list[IntPoint]]]] = {}
@@ -76,6 +79,10 @@ class RouteResult:
         self.connection_ends: list[tuple[str, str, str]] = []
         #: connections left unrouted: (net_no, one end, the other end)
         self.failed: list[tuple[int, str, str]] = []
+        #: half width of each net routed wider than the default (its class)
+        self.net_half: dict[int, int] = {}
+        #: connections of a wider class that only fitted at the default width
+        self.narrowed: list[tuple[int, str, str]] = []
 
     def add_wire(self, net_no: int, layer: int, path: list[IntPoint]) -> None:
         self.wires.setdefault(net_no, []).append((layer, path))
@@ -114,6 +121,8 @@ class _Connection:
         "a_end",
         "b_end",
         "path",
+        "narrow",
+        "half",
     )
 
     def __init__(self, index: int, net_no: int, a: Pin, b: Pin) -> None:
@@ -137,6 +146,10 @@ class _Connection:
         self.b_end: Pin | None = b
         # the node path last committed, so a rip-up can be undone
         self.path: list[Node] | None = None
+        # a connection of a wider class that did not fit at that width is
+        # routed at the default width instead; the half width it went in at
+        self.narrow = False
+        self.half = 0
 
 
 class GridRouter:
@@ -163,6 +176,7 @@ class GridRouter:
         route_first: frozenset | None = None,
         access_cost: float = 0.0,
         rollback: bool = True,
+        net_widths: dict[int, int] | None = None,
     ) -> None:
         self.board = board
         # Pin access: while a pin still has connections to route, the cells
@@ -223,6 +237,17 @@ class GridRouter:
         self.edge_clearance = 0 if edge_clearance is None else edge_clearance
         need = self.via_half + self.clearance + self.half_width
         self.via_reach = max(0, math.ceil(need / self.step) - 1)
+        # Net classes wider than the default: the grid is laid out for the
+        # default width, so a wider trace must also find the cells around its
+        # own free, out to its extra half width, and claims a wider halo.
+        self._net_half = {
+            net: max(width // 2, 1)
+            for net, width in (net_widths or {}).items()
+            if width // 2 > self.half_width
+        }
+        self._spread: list[tuple[int, int]] = []  # the current search's
+        self._cur_half = self.half_width
+        self._halo_by_half: dict[int, list[tuple[int, int]]] = {self.half_width: self._halo_offsets}
 
         if layers is None:
             layers = [i for i, layer in enumerate(board.layer_structure.arr) if layer.is_signal]
@@ -386,6 +411,30 @@ class GridRouter:
         allow_ripup: bool,
         conns: list[_Connection],
         wire_keepout: bool = True,
+    ) -> float | None:
+        """:meth:`_enter_cost_base`, and for a trace wider than the default
+        the same for every cell its extra width reaches (the worst of them)."""
+        cost = self._enter_cost_base(cell, layer, net_no, allow_ripup, conns, wire_keepout)
+        if cost is None or not self._spread:
+            return cost
+        for dx, dy in self._spread:
+            c = (cell[0] + dx, cell[1] + dy)
+            if not (0 <= c[0] < self.cols and 0 <= c[1] < self.rows):
+                return None
+            more = self._enter_cost_base(c, layer, net_no, allow_ripup, conns, wire_keepout)
+            if more is None:
+                return None
+            cost = max(cost, more)
+        return cost
+
+    def _enter_cost_base(
+        self,
+        cell: Cell,
+        layer: int,
+        net_no: int,
+        allow_ripup: bool,
+        conns: list[_Connection],
+        wire_keepout: bool = True,
     ) -> float | None:
         """Cost to enter ``(cell, layer)`` for ``net_no``; ``None`` if blocked.
 
@@ -440,14 +489,58 @@ class GridRouter:
             for layer in self.layers:
                 if (*c, layer) in self._via_keepout:
                     return False
-                if self._enter_cost(c, layer, net_no, False, conns, wire_keepout=False) != 0.0:
+                if self._enter_cost_base(c, layer, net_no, False, conns, wire_keepout=False) != 0.0:
                     return False
         return True
 
     # --- A* search ----------------------------------------------------------
 
+    def _conn_half(self, conn: _Connection) -> int:
+        """The half width a connection is routed at: its class's, unless it
+        has fallen back to the default."""
+        return self.half_width if conn.narrow else self._net_half.get(conn.net_no, self.half_width)
+
+    def _spread_for(self, half: int) -> list[tuple[int, int]]:
+        """Cells a trace of ``half`` also needs free: those whose centre is
+        within its extra half width (plus half a cell, for the grid)."""
+        extra = half - self.half_width
+        if extra <= 0:
+            return []
+        reach = math.ceil(extra / self.step) + 1
+        limit = extra + self.step / 2
+        return [
+            (dx, dy)
+            for dx in range(-reach, reach + 1)
+            for dy in range(-reach, reach + 1)
+            if (dx or dy) and math.hypot(dx, dy) * self.step <= limit
+        ]
+
+    def _halo_for(self, half: int) -> list[tuple[int, int]]:
+        """Cells a committed trace of ``half`` claims from default-width traces."""
+        offsets = self._halo_by_half.get(half)
+        if offsets is None:
+            need = half + self.clearance + self.half_width
+            reach = math.ceil(need / self.step)
+            offsets = self._halo_by_half[half] = [
+                (dx, dy)
+                for dx in range(-reach, reach + 1)
+                for dy in range(-reach, reach + 1)
+                if (dx or dy) and math.hypot(dx, dy) * self.step < need
+            ]
+        return offsets
+
     def _search(
         self, conn: _Connection, allow_ripup: bool, conns: list[_Connection]
+    ) -> list[Node] | None:
+        half = self._conn_half(conn)
+        self._cur_half, self._spread = half, self._spread_for(half)
+        try:
+            return self._search_at_width(conn, allow_ripup, conns)
+        finally:
+            self._cur_half, self._spread = self.half_width, []
+
+    def _search_at_width(
+        self, conn: _Connection, allow_ripup: bool, conns: list[_Connection]
     ) -> list[Node] | None:
         goal_cell = self._group_target(conn.b_group)
         if not conn.b_group[0] and any(z.layer in self._power_layers for z in conn.b_group[1]):
@@ -589,12 +682,12 @@ class GridRouter:
             self._static_copper = copper
         return not any(net != net_no and box.overlaps(grown) for box, net in self._static_copper)
 
-    def _stub_cells(self, pin_location: IntPoint, cell: Cell) -> list[Cell]:
+    def _stub_cells(self, pin_location: IntPoint, cell: Cell, half: int | None = None) -> list[Cell]:
         """Cells where another net's trace would come too close to the stub."""
         from freeroute.board.outline import _point_segment
 
         end = self._cell_center(cell)
-        reach = 2 * self.half_width + self.clearance
+        reach = (half or self._cur_half) + self.half_width + self.clearance
         box = IntBox(
             min(pin_location.x, end.x), min(pin_location.y, end.y),
             max(pin_location.x, end.x), max(pin_location.y, end.y),
@@ -616,12 +709,12 @@ class GridRouter:
 
             end = self._cell_center(cell)
             if end != pin.location:
-                for tile in PolylineShape(Polyline([pin.location, end]), self.half_width).tiles():
+                for tile in PolylineShape(Polyline([pin.location, end]), self._cur_half).tiles():
                     grown = tile.offset(self.clearance)
                     if any(k.overlaps(grown if needs else tile) for k, needs in keepouts):
                         return False
                 # the track's round end at the pin, for a rule area
-                cap = corner_box(pin.location, self.half_width)
+                cap = corner_box(pin.location, self._cur_half)
                 if any(not needs and k.overlaps(cap) for k, needs in keepouts):
                     return False
         if keepouts_only:
@@ -862,9 +955,11 @@ class GridRouter:
         conn.via_cells = list(via_cells)
         for cell, layer in conn.trace_cells:
             self._cell_owner[(*cell, layer)] = conn.index
+        conn.half = half = self._conn_half(conn)
+        halo = self._halo_for(half)
         conn.halo_nodes = []
         for (cx, cy), layer in conn.trace_cells:
-            for dx, dy in self._halo_offsets:
+            for dx, dy in halo:
                 x, y = cx + dx, cy + dy
                 if 0 <= x < self.cols and 0 <= y < self.rows:
                     node = (x, y, layer)
@@ -881,7 +976,7 @@ class GridRouter:
             if not isinstance(pin, Pin):
                 continue  # ended on a zone or a plane: no stub
             cell = cells[at]
-            for c in self._stub_cells(pin.location, cell):
+            for c in self._stub_cells(pin.location, cell, half):
                 node = (*c, layer)
                 if node not in self._cell_owner:
                     self._cell_owner[node] = conn.index
@@ -1012,6 +1107,7 @@ class GridRouter:
         best_count = -1
         best_snapshot: list[tuple[int, list, list]] | None = None
         best_unrouted = len(conns)
+        best_widths: tuple[dict[int, int], list] = ({}, [])
         # conns[i].index == i is what rip-up relies on, so shuffle a view
         order = list(conns)
         if self.seed is not None:
@@ -1031,13 +1127,25 @@ class GridRouter:
                 best_count = routed_count
                 best_unrouted = len(conns) - routed_count
                 best_snapshot = self._snapshot(conns)
+                best_widths = self._net_widths(conns)
             if routed_count == len(conns):
                 break
             if not changed:
                 break
-        return self._result_from(best_snapshot or [], best_unrouted)
+        result = self._result_from(best_snapshot or [], best_unrouted)
+        result.net_half, result.narrowed = best_widths
+        return result
 
     def _try_route(self, conn: _Connection, conns: list[_Connection]) -> bool:
+        if self._route_once(conn, conns):
+            return True
+        if conn.narrow or conn.net_no not in self._net_half:
+            return False
+        # a wider class that does not fit: route it at the default width
+        conn.narrow = True
+        return self._route_once(conn, conns)
+
+    def _route_once(self, conn: _Connection, conns: list[_Connection]) -> bool:
         path = self._search(conn, allow_ripup=False, conns=conns)
         if path is None:
             if not self.rip_up:
@@ -1124,6 +1232,21 @@ class GridRouter:
                 by_net.setdefault(net_no, []).append(pin)
         return by_net
 
+    def _net_widths(self, conns: list[_Connection]) -> tuple[dict[int, int], list]:
+        """Half width of each wider-class net whose routed connections all went
+        in at it (a net is written at one width), and the connections that
+        had to fall back to the default."""
+        halves: dict[int, int] = {}
+        narrowed = []
+        for c in conns:
+            if not c.routed:
+                continue
+            halves[c.net_no] = min(halves.get(c.net_no, c.half), c.half)
+            if c.narrow:
+                narrowed.append((c.net_no, *_ends_of(c)))
+        wide = {net: half for net, half in halves.items() if half > self.half_width}
+        return wide, narrowed
+
     def _snapshot(self, conns: list[_Connection]) -> list[tuple]:
         return [
             (c.net_no, [(layer, list(pts)) for layer, pts in c.wires], list(c.vias),
@@ -1284,6 +1407,7 @@ def route_board(
     route_first: frozenset | None = None,
     access_cost: float = 0.0,
     rollback: bool = True,
+    net_widths: dict[int, int] | None = None,
 ) -> RouteResult:
     """Convenience wrapper: build a :class:`GridRouter` and route the board."""
     router = GridRouter(
@@ -1303,5 +1427,6 @@ def route_board(
         route_first=route_first,
         access_cost=access_cost,
         rollback=rollback,
+        net_widths=net_widths,
     )
     return router.route()

src/freeroute/route/pipeline.py

@@ -34,6 +34,25 @@ def _rule_width_dsn(dsn: DsnBoard) -> float:
     return rules[0].value if rules else _DEFAULT_WIDTH_DSN
 
 
+def _net_widths_board(dsn: DsnBoard, scale: int) -> dict[int, int]:
+    """Track width of every net whose class asks for more than the default,
+    in board units, by net number (build_board numbers nets in DSN order)."""
+    default = _rule_width_dsn(dsn)
+    by_name: dict[str, float] = {}
+    for net_class in dsn.net_classes:
+        if not net_class.width_rules:
+            continue
+        width = net_class.width_rules[0].value
+        if width > default:
+            for name in net_class.net_names:
+                by_name[name] = max(by_name.get(name, 0.0), width)
+    return {
+        i + 1: round(by_name[net.name] * scale)
+        for i, net in enumerate(dsn.nets)
+        if net.name in by_name
+    }
+
+
 def _rule_clearance_dsn(dsn: DsnBoard) -> float:
     for rule in dsn.structure_rules.clearance_rules:
         if not rule.class_pairs:  # the layer-wide default clearance
@@ -108,6 +127,7 @@ def route_dsn_board(
         route_first=route_first,
         access_cost=access_cost,
         rollback=rollback,
+        net_widths=_net_widths_board(dsn, scale),
     )
     return result, scale, [layer.name for layer in dsn.layers]
 
@@ -122,6 +142,9 @@ def _to_routing_result(route, dsn: DsnBoard, scale: int, layer_names: list[str])
     result = RoutingResult()
     for net_no, segments in route.wires.items():
         name = numbers_to_names.get(net_no, str(net_no))
+        # its class's width when every connection of the net went in at it
+        half = getattr(route, "net_half", {}).get(net_no)
+        net_width = 2 * half / scale if half else width_dsn
         for layer_index, path in segments:
             layer_name = layer_names[layer_index] if layer_index < len(layer_names) else "F.Cu"
             coords: list[float] = []
@@ -129,7 +152,7 @@ def _to_routing_result(route, dsn: DsnBoard, scale: int, layer_names: list[str])
                 coords.append(point.x / scale)
                 coords.append(point.y / scale)
             if len(coords) >= 4:
-                result.add_wire(name, RoutedWire(layer=layer_name, width=width_dsn, coords=coords))
+                result.add_wire(name, RoutedWire(layer=layer_name, width=net_width, coords=coords))
     for net_no, locations in route.vias.items():
         name = numbers_to_names.get(net_no, str(net_no))
         for loc in locations:
@@ -137,6 +160,9 @@ def _to_routing_result(route, dsn: DsnBoard, scale: int, layer_names: list[str])
     result.unrouted = [
         (numbers_to_names.get(n, str(n)), a, b, zone) for n, a, b, zone in getattr(route, "failed", [])
     ]
+    result.narrowed = [
+        (numbers_to_names.get(n, str(n)), a, b) for n, a, b in getattr(route, "narrowed", [])
+    ]
     return result
 
 
@@ -207,6 +233,7 @@ def route_dsn_board_exact(
         route_first=route_first,
         access_cost=access_cost,
         rollback=rollback,
+        net_widths=_net_widths_board(dsn, scale),
     )
     return exact, scale, [layer.name for layer in dsn.layers]
 

src/freeroute/ses/model.py

@@ -60,6 +60,9 @@ class RoutingResult:
     #: connections the router could not make: (net name, one end, other end,
     #: the zone both ends sit in or "") -- a zone's fill may join the latter
     unrouted: list[tuple[str, str, str, str]] = field(default_factory=list)
+    #: connections of a wider net class that only fitted at the default width
+    #: (net name, one end, other end); their net is written at the default
+    narrowed: list[tuple[str, str, str]] = field(default_factory=list)
 
     def net(self, name: str, *, create: bool = False) -> RoutedNet | None:
         """Return the :class:`RoutedNet` with ``name`` (creating it if asked)."""

tests/route/test_net_widths.py

@@ -0,0 +1,42 @@
+"""Net classes wider than the default are routed at their width where it fits."""
+
+from __future__ import annotations
+
+from freeroute.dsn import parse_dsn
+from freeroute.route.pipeline import build_exact_routing_result
+
+_BOARD = """(pcb widths (parser) (resolution um 10) (unit um)
+  (structure
+    (layer F.Cu (type signal))
+    (boundary (path pcb 0  0 0  20000 0  20000 -10000  0 -10000  0 0))
+    {keepouts}
+    (rule (width 150) (clearance 150)))
+  (placement (component S (place P1 2000 -5000 front 0) (place P2 18000 -5000 front 0)))
+  (library (image S (pin pad 1 0 0)) (padstack pad (shape (rect F.Cu -600 -600 600 600)) (attach off)))
+  (network (net PWR (pins P1-1 P2-1))
+    (class Power PWR (rule (width 400) (clearance 150)))))"""
+
+# two keepouts leave a 0.65 mm channel: room for 0.15 mm (0.45), not for 0.4 mm (0.7)
+_CHANNEL = (
+    '(keepout "" (polygon F.Cu 0  9000 0  11000 0  11000 -4675  9000 -4675))\n'
+    '    (keepout "" (polygon F.Cu 0  9000 -5325  11000 -5325  11000 -10000  9000 -10000))'
+)
+
+
+def _route(keepouts=""):
+    return build_exact_routing_result(parse_dsn(_BOARD.format(keepouts=keepouts)), resolution=2)
+
+
+def test_a_wider_class_is_routed_and_written_at_its_width():
+    result = _route()
+    assert result.unrouted == [] and result.narrowed == []
+    widths = {w.width for net in result.nets for w in net.wires}
+    assert widths == {400.0}
+
+
+def test_a_wider_class_that_does_not_fit_falls_back_to_the_default():
+    result = _route(_CHANNEL)
+    assert result.unrouted == []
+    assert [net for net, _a, _b in result.narrowed] == ["PWR"]
+    widths = {w.width for net in result.nets for w in net.wires}
+    assert widths == {150.0}