Perform only one connexion to the power supplies and the corona ring.

* Bug: In cumulus/plugins.chip.pads, we were connecting the ground and
    power supplies to all the horizontal wires in the corona ring.
    But, when there are more than one and especially at the outer
    border of the pad, the vertical connecting wire will create
    various shorts over the pad.
      Now we connect only to the innermost horizontal wire only.
    Had to chech if the core side of the pad is north or south.

cumulus/src/plugins/alpha/chip/configuration.py

@@ -94,6 +94,7 @@ class ChipConf ( BlockConf ):
 #       trace( 550, '\tONE LAMBDA = %s\n' % DbU.getValueString(DbU.fromLambda(1.0)) )
         self.validated = True
         # Block Corona parameters (triggers loading from disk).
+        self.cfg.chip.padCoreSide          = None
         self.cfg.chip.supplyRailWidth      = None
         self.cfg.chip.supplyRailPitch      = None
         self.cfg.chip.block.rails.count    = None
@@ -112,6 +113,10 @@ class ChipConf ( BlockConf ):
         self.padsHavePosition = False
         trace( 550, '-' )
 
+    @property
+    def padCoreSide ( self ):
+        return self.cfg.chip.padCoreSide
+
     @property
     def railsCount ( self ):
         return self._railsCount

cumulus/src/plugins/alpha/chip/pads.py

@@ -16,6 +16,7 @@
 from   __future__   import print_function
 import sys
 import re
+import copy
 from   operator     import itemgetter  
 from   Hurricane    import DbU, Point, Transformation, Interval, Box,   \
                            Path, Occurrence, UpdateSession, Layer,      \
@@ -952,6 +953,7 @@ class Corona ( object ):
                                                   , component.getLayer()
                                                   , axis
                                                   , width ) )
+        self.padRails.sort( key=itemgetter(2) )
   
     def _createCoreWire ( self, chipIntNet, padNet, padInstance, count ):
         trace( 550, ',+', '\tCorona._createCoreWire()\n' )
@@ -1136,8 +1138,13 @@ class Corona ( object ):
         chipLayer        = self.conf.getRoutingLayer( self.conf.routingGauge.getPowerSupplyGauge().getDepth() - 1 )
         coronaAb         = self.conf.icorona.getAbutmentBox()
         chipAxis         = coronaAxis + self.conf.icorona.getTransformation().getTx()
+        rails = []
         trace( 550, '\tchipLayer={}\n'.format(chipLayer) )
         for rail in self.padRails:
+            rails.append( [ rail[0], rail[1], rail[2], rail[3] ] )
+        if self.conf.padCoreSide == 'North':
+            rails.reverse()
+        for rail in rails:
             net      = rail[0]
             layer    = rail[1]
             railAxis = rail[2]
@@ -1145,6 +1152,7 @@ class Corona ( object ):
             if net != chipNet or chipLayer.getMask() != layer.getMask():
                 continue
             if side == North:
+                trace( 550, '\tNorth side supply\n' )
                 trace( 550, '\tcoronaAb={}\n'.format(coronaAb) )
                 trace( 550, '\tcoronaAxis={}\n'.format(DbU.getValueString(coronaAxis)) ) 
                 trace( 550, '\tchipAxis={}\n'.format(DbU.getValueString(chipAxis)) )
@@ -1180,7 +1188,14 @@ class Corona ( object ):
                                 )
                 trace( 550, '\tpin={}\n'.format(pin) )
                 self.powerCount += 1
+                break
             elif side == South:
+                trace( 550, '\tSouth side supply\n' )
+                trace( 550, '\tcoronaAb={}\n'.format(coronaAb) )
+                trace( 550, '\tcoronaAxis={}\n'.format(DbU.getValueString(coronaAxis)) ) 
+                trace( 550, '\tchipAxis={}\n'.format(DbU.getValueString(chipAxis)) )
+                trace( 550, '\trailNet={} <-> {}\n'.format(net,chipNet) )
+                trace( 550, '\trailAxis={}\n'.format(DbU.getValueString(railAxis)) )
                 Vertical.create( chipNet
                                , supplyLayer
                                , chipAxis
@@ -1209,6 +1224,7 @@ class Corona ( object ):
                                 , DbU.fromLambda( 1.0 )
                                 )
                 self.powerCount += 1
+                break
         trace( 550, '-' )
 
     def doLayout ( self ):