Prevent multiple dog-legs in non-preferred direction

compiler/router/hanan_graph.py

@@ -96,7 +96,7 @@ class hanan_graph:
             if name == pin_name:
                 continue
             for pin in pins:
-                blockages.append(deepcopy(pin).inflated_pin(spacing=offset, multiple=1))
+                blockages.append(deepcopy(pin).inflated_pin(multiple=1, extra_spacing=offset))
         return blockages
 
 
@@ -110,13 +110,16 @@ class hanan_graph:
         y_values = set()
 
         # Add the source and target values
+        offset = self.router.layer_widths[0] / 2
+        x_offset = vector(offset, 0)
+        y_offset = vector(0, offset)
         for shape in [self.source, self.target]:
             aspect_ratio = shape.width() / shape.height()
             # If the pin is tall or fat, add two points on the ends
             if aspect_ratio <= 0.5: # Tall pin
-                points = [shape.uc(), shape.bc()]
+                points = [shape.bc() + y_offset, shape.uc() - y_offset]
             elif aspect_ratio >= 2: # Fat pin
-                points = [shape.lc(), shape.rc()]
+                points = [shape.lc() + x_offset, shape.rc() - x_offset]
             else: # Square-like pin
                 points = [shape.center()]
             for p in points:
@@ -251,9 +254,14 @@ class hanan_graph:
                 path.append(current)
                 return path
 
+            # Get the previous node to better calculate the next costs
+            prev_node = None
+            if current.id in came_from:
+                prev_node = came_from[current.id]
+
             # Update neighbor scores
             for node in current.neighbors:
-                tentative_score = current.get_edge_cost(node) + g_scores[current.id]
+                tentative_score = current.get_edge_cost(node, prev_node) + g_scores[current.id]
                 if node.id not in g_scores or tentative_score < g_scores[node.id]:
                     came_from[node.id] = current
                     g_scores[node.id] = tentative_score

compiler/router/hanan_node.py

@@ -5,6 +5,7 @@
 #
 from openram.base.vector import vector
 from openram.base.vector3d import vector3d
+from openram.tech import drc
 
 
 class hanan_node:
@@ -48,14 +49,28 @@ class hanan_node:
             neighbor.neighbors.remove(self)
 
 
-    def get_edge_cost(self, other):
+    def get_direction(self, b):
+        """ Return the direction of path from a to b. """
+
+        horiz = self.center.x == b.center.x
+        vert = self.center.y == b.center.y
+        return (horiz, vert)
+
+
+    def get_edge_cost(self, other, prev_node=None):
         """ Get the cost of going from this node to the other node. """
 
         if other in self.neighbors:
             is_vertical = self.center.x == other.center.x
             layer_dist = self.center.distance(other.center)
+            # Edge is on non-preferred direction
             if is_vertical != bool(self.center.z):
                 layer_dist *= 2
+                # Wire bends towards non-preferred direction
+                # NOTE: Adding a fixed cost prevents multiple dog-legs in
+                # non-preferred direction
+                if prev_node and self.get_direction(prev_node) != self.get_direction(other):
+                    layer_dist += drc["grid"]
             via_dist = abs(self.center.z - other.center.z) * 2
             return layer_dist + via_dist
         return float("inf")

compiler/router/hanan_router.py

@@ -142,7 +142,7 @@ class hanan_router(router_tech):
         # Inflate the shapes to prevent DRC errors
         offset = self.layer_widths[0] / 2
         for blockage in blockages:
-            self.blockages.append(blockage.inflated_pin(spacing=offset, multiple=1))
+            self.blockages.append(blockage.inflated_pin(multiple=1, extra_spacing=offset))
 
 
     def add_path(self, path):
@@ -160,19 +160,13 @@ class hanan_router(router_tech):
         the layout.
         """
 
-        def get_direction(a, b):
-            """ Return the direction of path from a to b. """
-            horiz = a.center.x == b.center.x
-            vert = a.center.y == b.center.y
-            return (horiz, vert)
-
         last_added = path[0]
         coordinates = [path[0].center]
-        direction = get_direction(path[0], path[1])
+        direction = path[0].get_direction(path[1])
         candidate = path[1]
         for i in range(2, len(path)):
             node = path[i]
-            current_direction = get_direction(candidate, node)
+            current_direction = node.get_direction(candidate)
             # Skip the previous candidate since the current node follows the
             # same direction
             if direction == current_direction:

compiler/router/hanan_shape.py

@@ -19,16 +19,13 @@ class hanan_shape(pin_layout):
         pin_layout.__init__(self, name, rect, layer_name_pp)
 
 
-    def inflated_pin(self, spacing=None, multiple=0.5):
+    def inflated_pin(self, spacing=None, multiple=0.5, extra_spacing=0):
         """ Override the default inflated_pin behavior. """
 
-        if not spacing:
-            spacing = 0
-        drc_spacing = multiple * drc("{0}_to_{0}".format(self.layer))
-        spacing = vector([spacing + drc_spacing] * 2)
-        (ll, ur) = self.rect
-        newll = ll - spacing
-        newur = ur + spacing
+        ll, ur = self.inflate(spacing, multiple)
+        extra = vector([extra_spacing] * 2)
+        newll = ll - extra
+        newur = ur + extra
         inflated_area = (newll, newur)
         return hanan_shape(self.name, inflated_area, self.layer)