From c8da4a343d3e38f576606f4f6bcacf825c2191ae Mon Sep 17 00:00:00 2001
From: Niko Savola <nikosavola@google.com>
Date: Fri, 13 Oct 2023 18:16:56 -0700
Subject: [PATCH 1/2] Generate technology if needed for netlist export

---
 gplugins/common/config.py       |  2 ++
 gplugins/klayout/get_netlist.py | 22 +++++++++++++++-------
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/gplugins/common/config.py b/gplugins/common/config.py
index 8393351a..a529eb29 100644
--- a/gplugins/common/config.py
+++ b/gplugins/common/config.py
@@ -22,6 +22,8 @@ class Path:
     results_tidy3d = home / ".tidy3d"
     test_data = repo / "test-data"
     sparameters_repo = test_data / "sp"
+    klayout = module_path / "klayout"
+    klayout_tech = klayout / "tech.lyt"
     extra = repo / "extra"
     cwd = pathlib.Path.cwd()
 
diff --git a/gplugins/klayout/get_netlist.py b/gplugins/klayout/get_netlist.py
index 63a5fa0b..dfc55708 100644
--- a/gplugins/klayout/get_netlist.py
+++ b/gplugins/klayout/get_netlist.py
@@ -1,7 +1,12 @@
+from pathlib import Path
+
+import gdsfactory as gf
 import kfactory as kf
 import klayout.db as kdb
 from gdsfactory.typings import PathType
 
+from gplugins.common.config import PATH
+
 
 def get_l2n(
     gdspath: PathType, klayout_tech_path: PathType | None = None
@@ -20,13 +25,18 @@ def get_l2n(
     lib.read(filename=str(gdspath))
     c = lib[0]
 
-    if klayout_tech_path:
-        technology = kdb.Technology()
-        technology.load(str(klayout_tech_path))
+    tech_dir = PATH.klayout
+    tech_dir.mkdir(exist_ok=True, parents=True)
+    if not klayout_tech_path:
+        gf.get_active_pdk().klayout_technology.write_tech(tech_dir)
+        klayout_tech_path = Path(tech_dir) / "tech.lyt"
+
+    technology = kdb.Technology()
+    technology.load(str(klayout_tech_path))
+    lib.technology_name = technology.name
 
     l2n = kf.kdb.LayoutToNetlist(c.begin_shapes_rec(0))
-    l2n.threads = kf.config.n_threads
-    for l_idx in c.kcl.layer_indexes():
+    for l_idx in c.kcl.layer_indices():
         l2n.connect(l2n.make_layer(l_idx, f"layer{l_idx}"))
     l2n.extract_netlist()
     return l2n
@@ -52,8 +62,6 @@ def get_netlist(gdspath: PathType, **kwargs) -> kdb.Netlist:
 if __name__ == "__main__":
     from gdsfactory.samples.demo.lvs import pads_correct, pads_shorted
 
-    from gplugins.common.config import PATH
-
     c = pads_correct()
     c = pads_shorted()
     gdspath = c.write_gds()

From 9ba5c1020364642d5fd0fdc9f9c60519bbaa5131 Mon Sep 17 00:00:00 2001
From: Niko Savola <nikosavola@google.com>
Date: Mon, 16 Oct 2023 16:19:04 -0700
Subject: [PATCH 2/2] Specify connections for `LayoutToNetlist` manually
 instead of using technologies

See
https://github.com/KLayout/klayout/issues/1223#issuecomment-1349644804
for justification using this approach
---
 gplugins/klayout/get_netlist.py | 53 ++++++++++++++++++++++++++-------
 1 file changed, 43 insertions(+), 10 deletions(-)

diff --git a/gplugins/klayout/get_netlist.py b/gplugins/klayout/get_netlist.py
index dfc55708..b18031b5 100644
--- a/gplugins/klayout/get_netlist.py
+++ b/gplugins/klayout/get_netlist.py
@@ -1,5 +1,3 @@
-from pathlib import Path
-
 import gdsfactory as gf
 import kfactory as kf
 import klayout.db as kdb
@@ -22,22 +20,57 @@ def get_l2n(
 
     """
     lib = kf.kcell.KCLayout(str(gdspath))
-    lib.read(filename=str(gdspath))
-    c = lib[0]
+    Tech = kdb.Technology()
 
     tech_dir = PATH.klayout
     tech_dir.mkdir(exist_ok=True, parents=True)
     if not klayout_tech_path:
         gf.get_active_pdk().klayout_technology.write_tech(tech_dir)
-        klayout_tech_path = Path(tech_dir) / "tech.lyt"
+        klayout_tech_path = tech_dir
 
-    technology = kdb.Technology()
-    technology.load(str(klayout_tech_path))
-    lib.technology_name = technology.name
+    # klayout tech path is now assumed to contain a `tech.lyt`` file to use
+    technology = Tech.load(str(klayout_tech_path / "tech.lyt"))
+
+    lib.read(filename=str(gdspath))
+    c = lib[0]
 
     l2n = kf.kdb.LayoutToNetlist(c.begin_shapes_rec(0))
-    for l_idx in c.kcl.layer_indices():
-        l2n.connect(l2n.make_layer(l_idx, f"layer{l_idx}"))
+    l2n.threads = kf.config.n_threads
+
+    reversed_layer_map = dict()
+    for k, v in gf.get_active_pdk().layers.items():
+        reversed_layer_map[v] = reversed_layer_map.get(v, set()) | {k}
+
+    # define stack connections through vias
+    layer_connection_iter = [
+        [
+            (connection.layer_a(), connection.via_layer(), connection.layer_b())
+            for connection in connectivity.each_connection()
+        ]
+        for connectivity in technology.component("connectivity").each()
+    ][0]
+    correct_layer_names = set(sum(layer_connection_iter, ()))
+
+    # define the layers to be extracted
+    for l_idx in c.kcl.layer_indexes():
+        layer_info = c.kcl.get_info(l_idx)
+        names = reversed_layer_map[(layer_info.layer, layer_info.datatype)]
+        try:
+            same_name_as_in_connections = next(iter(correct_layer_names & names))
+        except StopIteration:
+            same_name_as_in_connections = next(iter(names))
+        l2n.connect(l2n.make_layer(l_idx, same_name_as_in_connections))
+
+    for layer_a, layer_via, layer_b in (
+        (l2n.layer_by_name(layer) for layer in layers)
+        for layers in layer_connection_iter
+    ):
+        # Don't try to connect Nones
+        if all((layer_a, layer_via)):
+            l2n.connect(layer_a, layer_via)
+        if all((layer_b, layer_via)):
+            l2n.connect(layer_via, layer_b)
+
     l2n.extract_netlist()
     return l2n