From ea5eda91fcacdcb211d106abf51d885da33a392c Mon Sep 17 00:00:00 2001
From: Matt Guthaus <mrg@ucsc.edu>
Date: Fri, 2 Feb 2018 12:27:24 -0800
Subject: [PATCH] Connect all gnd rails of RBL.

---
 compiler/replica_bitline.py | 31 +++++++++++++------------------
 1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/compiler/replica_bitline.py b/compiler/replica_bitline.py
index bed1ebb2..9345cb48 100644
--- a/compiler/replica_bitline.py
+++ b/compiler/replica_bitline.py
@@ -242,16 +242,11 @@ class replica_bitline(design.design):
         # Add a rail in M1 from bottom to two along delay chain
         gnd_start = self.rbl_inv_inst.get_pin("gnd").ll() - self.offset_fix
         
-        # It is the height of the entire RBL and bitcell
-        self.add_rect(layer="metal2",
-                      offset=gnd_start,
-                      width=self.m2_width,
-                      height=self.rbl.height+self.bitcell.height+self.inv.width+self.m2_pitch)
         self.add_layout_pin(text="gnd",
-                            layer="metal1",
+                            layer="metal2",
                             offset=gnd_start.scale(1,0),
                             width=self.m2_width,
-                            height=2*self.inv.width)
+                            height=self.rbl_inst.uy()+2*self.m2_pitch)
                       
         # Connect the WL pins directly to gnd
         for row in range(self.rows):
@@ -275,20 +270,20 @@ class replica_bitline(design.design):
         self.add_via(layers=("metal1", "via1", "metal2"),
                      offset=offset)
 
-        # Connect the bitcell gnd pin to the rail
+        # Connect the bitcell gnd pins to the rail
         gnd_pins = self.get_pins("gnd")
-        gnd_start = gnd_pins[0].uc()
+        gnd_start = gnd_pins[0].ul()
+        self.add_via_center(layers=("metal1", "via1", "metal2"),
+                            offset=gnd_pins[0].uc())
         rbl_gnd_pins = self.rbl_inst.get_pins("gnd")
-        # Find the left most rail on M2
-        gnd_pin = None
+        # Add L shapes to each vertical gnd rail
         for pin in rbl_gnd_pins:
-            if gnd_pin == None or (pin.layer=="metal2" and pin.lx()<gnd_pin.lx()):
-                gnd_pin = pin
-        gnd_end = gnd_pin.uc()
-        # Add a couple midpoints so that the wire will drop a via and then route horizontal on M1
-        gnd_mid1 = gnd_start + vector(0,self.m2_pitch)
-        gnd_mid2 = gnd_end + vector(0,self.m2_pitch)
-        self.add_wire(("metal1","via1","metal2"), [gnd_start, gnd_mid1, gnd_mid2, gnd_end])
+            if pin.layer != "metal2":
+                continue
+            gnd_end = pin.uc()
+            gnd_mid = vector(gnd_end.x, gnd_start.y)
+            self.add_wire(("metal1","via1","metal2"), [gnd_start, gnd_mid, gnd_end])
+            gnd_start = gnd_mid
         
 
         # Add a second gnd pin to the second delay chain rail. No need for full length.