From 7598485a4f8167e32db9b124594a5a3f1a240dfe Mon Sep 17 00:00:00 2001
From: Jean-Paul Chaput <Jean-Paul.Chaput@lip6.fr>
Date: Sat, 14 Jan 2023 22:38:36 +0100
Subject: [PATCH] Allow the BigVia to stack the cuts in some cases.

---
 cumulus/src/plugins/alpha/block/bigvia.py | 31 +++++++++++++++++++----
 cumulus/src/plugins/alpha/chip/corona.py  | 10 ++++++--
 2 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/cumulus/src/plugins/alpha/block/bigvia.py b/cumulus/src/plugins/alpha/block/bigvia.py
index a395e915..f7095210 100644
--- a/cumulus/src/plugins/alpha/block/bigvia.py
+++ b/cumulus/src/plugins/alpha/block/bigvia.py
@@ -41,6 +41,7 @@ class BigVia ( object ):
     AllowBotMetalExpand   = 0x0002
     AllowHorizontalExpand = 0x0004
     AllowVerticalExpand   = 0x0008
+    StackVias             = 0x0010
     AllowAllExpand        = AllowTopMetalExpand   \
                           | AllowBotMetalExpand   \
                           | AllowHorizontalExpand \
@@ -162,11 +163,22 @@ class BigVia ( object ):
                               , self.widths [depth] - DbU.fromLambda( 1.0 )
                               , self.heights[depth] - DbU.fromLambda( 1.0 ) )
         else:
+            cutMatrixes = []
             for depth in range(self.bottomDepth,self.topDepth):
-                self._doCutMatrix( depth )
+                cutMatrixes.append( self._computeCutMatrix( depth ))
+            if self.flags & BigVia.StackVias:
+                maxCutMatrix = cutMatrixes[0]
+                for cutMatrix in cutMatrixes:
+                    if maxCutMatrix[0] + maxCutMatrix[1] < cutMatrix[0] + cutMatrix[1]:
+                        maxCutMatrix = cutMatrix
+                for cutMatrix in cutMatrixes:
+                    cutMatrix[1] = maxCutMatrix[0] + maxCutMatrix[1] - cutMatrix[0]
+                    cutMatrix[2] = maxCutMatrix[2]
+            for depth in range(self.bottomDepth,self.topDepth):
+                self._doCutMatrix( depth, cutMatrixes[ depth - self.bottomDepth ] )
         self.hasLayout = True
 
-    def _doCutMatrix ( self, depth ):
+    def _computeCutMatrix ( self, depth ):
         viaLayer     = rg.getContactLayer( depth )
         cutLayer     = viaLayer.getCut()
         cutSide      = cutLayer.getMinimalSize()
@@ -207,9 +219,18 @@ class BigVia ( object ):
                                          .format( cutLayer.getName(), self )
                                        , 'Height is too small to fit a single VIA cut.' 
                                        ] )
-        cutArea.inflate( -hEnclosure, -vEnclosure )
-        xoffset = (cutArea.getWidth () % (cutSide+cutSpacing)) // 2
-        yoffset = (cutArea.getHeight() % (cutSide+cutSpacing)) // 2
+        return [cutSide, cutSpacing, hEnclosure]
+
+    def _doCutMatrix ( self, depth, cutMatrix ):
+        cutSide    = cutMatrix[0]
+        cutSpacing = cutMatrix[1]
+        hEnclosure = cutMatrix[2]
+        viaLayer   = rg.getContactLayer( depth )
+        cutLayer   = viaLayer.getCut()
+        cutArea    = self.plates[ depth ].getBoundingBox()
+        cutArea.inflate( -hEnclosure, -hEnclosure )
+        xoffset    = (cutArea.getWidth () % (cutSide+cutSpacing)) // 2
+        yoffset    = (cutArea.getHeight() % (cutSide+cutSpacing)) // 2
         cutArea.translate( xoffset, yoffset )
         self.vias[ depth ] = []
         y = cutArea.getYMin()
diff --git a/cumulus/src/plugins/alpha/chip/corona.py b/cumulus/src/plugins/alpha/chip/corona.py
index 65e41802..aa61d69f 100644
--- a/cumulus/src/plugins/alpha/chip/corona.py
+++ b/cumulus/src/plugins/alpha/chip/corona.py
@@ -138,9 +138,12 @@ class HorizontalRail ( Rail ):
     def connect ( self, contact ):
         viaWidth  = contact.getWidth()
         viaHeight = self.side.hRailWidth
+        viaFlags  = BigVia.AllowAllExpand
         if self.conf.routingGauge.isSymbolic():
             viaWidth  -= DbU.fromLambda( 1.0 )
             viaHeight -= DbU.fromLambda( 1.0 )
+        if self.conf.cfg.katana.disableStackedVias:
+            viaFlags |= BigVia.StackVias
         self.vias[ contact.getX() ] = [ contact.getX()
                                       , BigVia( self.net
                                               , self.side.getLayerDepth(self.side.getHLayer())
@@ -148,7 +151,7 @@ class HorizontalRail ( Rail ):
                                               , self.axis
                                               , viaWidth
                                               , viaHeight
-                                              , flags=BigVia.AllowAllExpand )
+                                              , flags=viaFlags )
                                       , contact ]
         trace( 550, '\tADD "{}" contact "{}" @ [{} {}]\n' \
                .format( contact.getNet().getName()
@@ -286,9 +289,12 @@ class VerticalRail ( Rail ):
             return False
         viaWidth  = self.side.vRailWidth
         viaHeight = contact.getHeight()
+        viaFlags  = BigVia.AllowAllExpand
         if self.conf.routingGauge.isSymbolic():
             viaWidth  -= DbU.fromLambda( 1.0 )
             viaHeight -= DbU.fromLambda( 1.0 )
+        if self.conf.cfg.katana.disableStackedVias:
+            viaFlags |= BigVia.StackVias
         self.vias[ contact.getY() ] = [ contact.getY()
                                       , BigVia( self.net
                                               , self.side.getLayerDepth(self.side.getVLayer())
@@ -296,7 +302,7 @@ class VerticalRail ( Rail ):
                                               , contact.getY()
                                               , self.side.vRailWidth - DbU.fromLambda(1.0)
                                               , contact.getHeight()  - DbU.fromLambda(1.0)
-                                              , flags=BigVia.AllowAllExpand )
+                                              , flags=viaFlags )
                                       , contact ]
         self.vias[ contact.getY() ][1].mergeDepth( self.side.getLayerDepth(contact.getLayer()) )
         trace( 550, '\t-> BigVIA {}\n'.format(self.vias[ contact.getY() ][1]) )