Hole spacing also from through-hole pads and fixed vias

A route could drop a via next to (or onto) a through-hole pad of its own
net, where it changes layer for free, and a via reusing a fixed via's
cell came out a little off the fixed via's centre, beside it. No via now
goes within hole spacing of a through-hole pad of any net; a via in a pad
is checked exactly against every via and hole; and a routed via on a
fixed via of its net is not written. charge-sense: 4 hole_to_hole to 0;
flight controller: 2 to 0, unconnected unchanged.

src/freeroute/route/exact_router.py

@@ -215,7 +215,8 @@ def route_board_exact(
         # connections of one net that end on the same plane cell share its
         # via: write it once, and never on top of a via already on the board
         acc.vias.extend(
-            v for v in dict.fromkeys(vias) if v not in acc.vias and (net_no, v) not in fixed_vias
+            v for v in dict.fromkeys(vias)
+            if v not in acc.vias and not _on_fixed_via(net_no, v, fixed_vias, via_half)
         )
         for box, box_layers in boxes:
             oid = next(owner)
@@ -645,6 +646,15 @@ def _end_in_rule_area(tree, wires, half_width) -> bool:
     return False
 
 
+def _on_fixed_via(net_no, point, fixed_vias, via_half) -> bool:
+    """A routed via that reuses a via already on the board: the grid put it
+    on the fixed via's cell, a little off its centre, and it is not written."""
+    return any(
+        net == net_no and abs(loc.x - point.x) <= via_half and abs(loc.y - point.y) <= via_half
+        for net, loc in fixed_vias
+    )
+
+
 def _copper_boxes(wires, vias, half_width, via_layers, via_half=None):
     via_half = via_half or half_width
     boxes: list[tuple[IntBox, frozenset[int]]] = []

src/freeroute/route/grid_router.py

@@ -257,6 +257,7 @@ class GridRouter:
         # an own-net via at the very same cell, which it simply reuses.
         drill = via_drill if via_drill else 2 * self.via_half
         need = drill + max(hole_to_hole, 0)
+        self._via_drill, self._hole_gap, self._hole_need = drill, max(hole_to_hole, 0), need
         reach = math.ceil(need / self.step)
         self._hole_offsets = [
             (dx, dy)
@@ -265,6 +266,7 @@ class GridRouter:
             if (dx or dy) and math.hypot(dx, dy) * self.step < need
         ]
         self._via_nets: dict[Cell, dict[int, int]] = {}  # routed via centres
+        self._via_centres: list[IntPoint] | None = None  # cache for _hole_clear_at
         self._fixed_vias: dict[Cell, int] = {}
         self._fixed_via_points: set[tuple[int, IntPoint]] = set()
 
@@ -299,6 +301,21 @@ class GridRouter:
             if isinstance(item, Via) and item.fixed and item.net_nos:
                 self._fixed_vias[self._cell_of(item.location)] = item.net_nos[0]
                 self._fixed_via_points.add((item.net_nos[0], item.location))
+        # Through-hole pads have holes too, and a route changes layer at one
+        # for free, so no via (of any net) goes within hole spacing of one.
+        # The DSN has no drill for a pad; its smaller half size stands in.
+        self._tht_holes: list[tuple[IntPoint, int]] = []
+        self._tht_block: set[Cell] = set()
+        for pin in board.get_pins():
+            if pin.shape is None or sum(1 for layer in pin.layers if layer in self.layers) < 2:
+                continue
+            box = pin.shape.bounding_box()
+            radius = min(box.ur.x - box.ll.x, box.ur.y - box.ll.y) // 2
+            reach = radius + self._via_drill // 2 + self._hole_gap
+            self._tht_holes.append((pin.location, reach))
+            ring = IntBox(pin.location.x, pin.location.y, pin.location.x, pin.location.y)
+            for cell in self._cells_in_box(ring, reach):
+                self._tht_block.add(cell)
 
     # --- grid helpers -------------------------------------------------------
 
@@ -524,7 +541,10 @@ class GridRouter:
         return nets
 
     def _holes_clear(self, cell: Cell, net_no: int) -> bool:
-        """No via centre within hole-to-hole reach, but an own-net one here."""
+        """No via centre within hole-to-hole reach, but an own-net one here,
+        and no through-hole pad's hole within reach at all."""
+        if cell in self._tht_block:
+            return False
         if self._via_nets_at(cell) - {net_no}:
             return False
         cx, cy = cell
@@ -717,7 +737,23 @@ class GridRouter:
             ]
             copper += [(box, net) for net, _, box in self.board.get_fixed_copper()]
             self._static_copper = copper
-        return not any(net != net_no and box.overlaps(grown) for box, net in self._static_copper)
+        if any(net != net_no and box.overlaps(grown) for box, net in self._static_copper):
+            return False
+        return self._hole_clear_at(point)
+
+    def _hole_clear_at(self, point: IntPoint) -> bool:
+        """Hole spacing measured exactly from ``point`` to every via and
+        through-hole pad (a via moved into a pad is not on its cell's centre)."""
+        need = self._hole_need
+        if self._via_centres is None:  # rebuilt only after vias change
+            self._via_centres = [loc for _net, loc in self._fixed_via_points] + [
+                self._cell_center(c) for c, count in self._via_nets.items() if any(count.values())
+            ]
+        if any(math.hypot(c.x - point.x, c.y - point.y) < need for c in self._via_centres):
+            return False
+        return not any(
+            math.hypot(loc.x - point.x, loc.y - point.y) < reach for loc, reach in self._tht_holes
+        )
 
     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."""
@@ -993,6 +1029,8 @@ class GridRouter:
         for cell in conn.via_cells:
             count = self._via_nets.setdefault(cell, {})
             count[conn.net_no] = count.get(conn.net_no, 0) + 1
+        if conn.via_cells:
+            self._via_centres = None
         for cell, layer in conn.trace_cells:
             self._cell_owner[(*cell, layer)] = conn.index
         conn.half = half = self._conn_half(conn)
@@ -1071,6 +1109,8 @@ class GridRouter:
             count = self._via_nets.get(cell)
             if count and count.get(conn.net_no):
                 count[conn.net_no] -= 1
+        if conn.via_cells:
+            self._via_centres = None
         conn.via_cells = []
         conn.wires = []
         conn.vias = []

tests/route/test_via_spacing.py

@@ -54,3 +54,47 @@ def test_connections_sharing_a_plane_via_write_it_once():
     vias = exact.result.vias[1]
     assert len(vias) < 8, "no via is shared, so this board no longer tests sharing"
     assert len(set(vias)) == len(vias), "a shared via written more than once"
+
+
+def _router(dsn_text):
+    from freeroute.board import build_board
+    from freeroute.route.grid_router import GridRouter
+    from freeroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn
+
+    dsn = parse_dsn(dsn_text)
+    s = dsn.resolution.value
+    return GridRouter(
+        build_board(dsn), trace_width=round(_rule_width_dsn(dsn) * s),
+        clearance=round(_rule_clearance_dsn(dsn) * s), resolution=2, orthogonal=True,
+        via_drill=300 * s, hole_to_hole=250 * s,
+    ), s
+
+
+_THT = """(pcb tht (parser) (resolution um 10) (unit um)
+  (structure (layer F.Cu (type signal)) (layer B.Cu (type signal))
+    (boundary (path pcb 0  0 0  20000 0  20000 -20000  0 -20000  0 0))
+    (via "Via[0-1]_500:300_um") (rule (width 150) (clearance 150)))
+  (placement (component T (place J1 10000 -10000 front 0)))
+  (library (image T (pin tht 1 0 0))
+    (padstack tht (shape (circle F.Cu 1700)) (shape (circle B.Cu 1700)) (attach off))
+    (padstack "Via[0-1]_500:300_um" (shape (circle F.Cu 500)) (shape (circle B.Cu 500)) (attach off)))
+  (network (net SIG (pins J1-1))))"""
+
+
+def test_no_via_goes_near_a_through_hole_pads_hole_even_of_its_own_net():
+    router, s = _router(_THT)
+    pin = router._cell_of(router.board.get_pins()[0].location)
+    assert not router._holes_clear(pin, 1)  # own net, right on the pad
+    far = (pin[0] + 40, pin[1])
+    assert router._holes_clear(far, 1)
+
+
+def test_a_via_in_a_pad_keeps_hole_spacing_from_a_fixed_via():
+    from freeroute.geometry import IntPoint
+
+    text = _THT.replace("(network (net SIG (pins J1-1))))",
+                        "(network (net SIG (pins J1-1)))\n"
+                        "  (wiring (via \"Via[0-1]_500:300_um\"  3000 -3000 (net SIG) (type route))))")
+    router, s = _router(text)
+    assert not router._hole_clear_at(IntPoint(3400 * s, -3000 * s))  # 0.4 mm < 0.55 mm
+    assert router._hole_clear_at(IntPoint(3600 * s, -3000 * s))