From 37f2ddffe8e8d6141b1abebbdd0bfe49fd174b3f Mon Sep 17 00:00:00 2001
From: Tim Edwards <tim@opencircuitdesign.com>
Date: Sun, 7 Apr 2024 10:42:59 -0400
Subject: [PATCH] Modified the deep nwell generation routine to draw the nwell
 boundary in four separate rectangles, because the method of drawing nwell
 over the area and erasing from the center causes unexpected/unwanted
 interactions with any existing layout in the center of the deep nwell region.

---
 VERSION                 |  2 +-
 sky130/magic/sky130.tcl | 33 +++++++++++++++++++++++++++++++--
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/VERSION b/VERSION
index 81b2e4af..c2126aa9 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.0.474
+1.0.475
diff --git a/sky130/magic/sky130.tcl b/sky130/magic/sky130.tcl
index c4d85172..48cec26a 100644
--- a/sky130/magic/sky130.tcl
+++ b/sky130/magic/sky130.tcl
@@ -549,9 +549,38 @@ proc sky130::deep_nwell_draw {} {
    pushbox
    pushbox
    box grow c 0.4um
+   # Note:  Previous implementation was to draw nwell over the whole
+   # area and then erase it from the center.  That can interact with
+   # any layout already drawn in the center area.  Instead, draw four
+   # separate rectangles.
+   # -----------------
+   # paint nwell
+   # box grow c -1.43um
+   # erase nwell
+   # -----------------
+   pushbox
+   box width 1.43um
+   paint nwell
+   popbox
+   pushbox
+   box height 1.43um
+   paint nwell
+   popbox
+   pushbox
+   box move n ${h}um
+   box move n 0.8um
+   box move s 1.43um
+   box height 1.43um
+   paint nwell
+   popbox
+   pushbox
+   box move e ${w}um
+   box move e 0.8um
+   box move w 1.43um
+   box width 1.43um
    paint nwell
-   box grow c -1.43um
-   erase nwell
+   popbox
+
    popbox
    box grow c 0.03um