Cleanup + helper functions

Removing redundant code from Danube River, moving it into a LibrePDK
helper function and removing redundancies within LibrePDK

contact.py

@@ -4,10 +4,37 @@ from gdsfactory.components.compass import compass
 from librepdk.structure import LibrePDKStructure
 import librepdk.helper as lph
 
-class ViaStripe(LibrePDKStructure):
-	device_layers = ['nwell','ndiffusion','pdiffusion', 'poly', 'pwell',]
-	min_row_vias = 1
+min_vias = 1
+
+device_layers = ['nwell','ndiffusion','pdiffusion', 'poly', 'pwell',]
+
+def get_biggest_via(config, from_layer, conlayer_name):
+	if from_layer in device_layers:
+		origlayer = 1
+	else:
+		origlayer = int(from_layer.replace("metal","").strip())
+
+	# what's the highest metal layer number?
+	toplayer = int(conlayer_name.replace("metal","").strip())
 
+	maxdim = 0
+	spacing = 0
+	for lidx in range(origlayer, toplayer):
+		vln = "via"+str(lidx)
+		vdim = config.get_via_size(vln)
+		space = config.get_min_spacing((vln,vln))
+		# find spacing of largest via layer
+		if vdim > maxdim:
+			maxdim = vdim
+			spacing = space
+
+	return maxdim, spacing
+
+def get_min_viagroup_pad_size(config, from_layer, conlayer_name):
+	maxdim, spacing = get_biggest_via(config, from_layer, conlayer_name)
+	return min_vias*(maxdim+spacing)
+
+class ViaStripe(LibrePDKStructure):
 	def __init__(self, config, name, from_layer, w, h, conlayer_name, less_vias=False):
 		LibrePDKStructure.__init__(self, config, name)
 		# the layers:
@@ -21,7 +48,7 @@ class ViaStripe(LibrePDKStructure):
 		viastackup = []
 		metalstackup = []
 
-		if self.from_layer in self.device_layers:
+		if self.from_layer in device_layers:
 			origlayer = 1
 			metalstackup.append(self.from_layer)
 		else:
@@ -46,8 +73,7 @@ class ViaStripe(LibrePDKStructure):
 		# the interconnects
 		via = gf.Component(self.name+"_single_via")
 
-		maxdim = 0
-		spacing = 0
+		maxdim, spacing = get_biggest_via(self.config, self.from_layer, self.conlayer_name)
 
 		for vln in viastackup:
 			vlid = self.config.get_layer_id(vln)
@@ -66,14 +92,14 @@ class ViaStripe(LibrePDKStructure):
 			col = w/(spacing+maxdim)
 			col = int(col)
 
-			if col < self.min_row_vias:
-				col = self.min_row_vias
+			if col < min_vias:
+				col = min_vias
 
 			row = h/(spacing+maxdim)
 			row = int(row)
 
-			if row < self.min_row_vias:
-				row = self.min_row_vias
+			if row < min_vias:
+				row = min_vias
 
 			if (maxdim+spacing)*col < w and not self.less_vias:
 				col += 1