From d9ab99499881fcfc7c93c9c0b02809a474b39bc7 Mon Sep 17 00:00:00 2001
From: Thomas Kramer <code@tkramer.ch>
Date: Thu, 23 Feb 2023 08:50:13 +0100
Subject: [PATCH] compute costs of terminal nodes and apply them to the graph
edges
---
lclayout/router.py | 26 ++++++++++++++++++++++++++
lclayout/routing_graph.py | 30 ++++++++++++++++++++++++++++++
2 files changed, 56 insertions(+)
diff --git a/lclayout/router.py b/lclayout/router.py
index 5b30982..de990f0 100644
--- a/lclayout/router.py
+++ b/lclayout/router.py
@@ -462,6 +462,32 @@ class DefaultRouter():
else:
assert False, 'Routing graph is not connected.'
+ # Set via weights based on terminal costs.
+ regions_by_layer = {
+ # Convert Shapes objects into db.Region for fast 'inside' checks.
+ layer: db.Region(s) for layer, s in shapes.items()
+ }
+ for net, ts in terminals_by_net:
+ for terminal_node in ts:
+ layer, (x, y) = terminal_node
+ possible_via_layers = (data['layer'] for _, _, data in via_layers.edges(layer, data=True))
+
+ for via_layer in possible_via_layers:
+ via_cost = compute_terminal_cost(
+ via_layer,
+ layer,
+ (x, y),
+ regions_by_layer[layer],
+ tech
+ )
+
+ other_node = via_layer, (x, y) # Node on the other side of the via.
+
+ if terminal_node in graph and other_node in graph:
+ # Scale the via cost
+ graph[terminal_node][other_node]['weight'] *= via_cost + 1
+
+
self._routing_graph = graph
# TODO: SPLIT HERE
diff --git a/lclayout/routing_graph.py b/lclayout/routing_graph.py
index 2354178..f1b8fe3 100644
--- a/lclayout/routing_graph.py
+++ b/lclayout/routing_graph.py
@@ -396,6 +396,36 @@ def _extract_terminal_nodes_from_shape(routing_nodes: Dict[Any, Set[Tuple[int, i
logger.debug(f"routing_terminals: {routing_terminals}")
return routing_terminals
+def compute_terminal_cost(
+ via_layer: str,
+ layer: str,
+ coord: Tuple[int, int],
+ layer_region: db.Region,
+ tech
+ ) -> int:
+ """
+ Compute the cost of placing a via on `via_layer` which connects to `layer` at `(x, y)`.
+ The cost is derived from the existing geometries on the layer.
+
+ TODO: Move to new module 'pin_access_analysis'
+
+ Returns an unscaled cost. 0 for vias which can be placed without extending the pin shape,
+ 1 for vias which would extend the pin shape.
+ """
+
+ enc = tech.minimum_enclosure.get((layer, via_layer), 0)
+ via_size = tech.via_size[via_layer]
+
+ d = enc + via_size // 2
+
+ # Test if the via would be completely enclosed in existing shapes.
+ is_enclosed = is_inside(coord, layer_region, d)
+
+ if is_enclosed:
+ # Via can be placed without extending the pin shape.
+ return 0
+ else:
+ return 1
def extract_terminal_nodes_by_lvs(graph: nx.Graph,
pin_shapes_by_net: Dict[str, List[List[Tuple[str, db.Polygon]]]],
--
GitLab