From 13a1bf713d59bb9481109fff911c5df390562cda Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@klayout.de>
Date: Sat, 4 Apr 2026 20:05:37 +0200
Subject: [PATCH] Added DRC integration and tests

---
 src/drc/drc/built-in-macros/_drc_engine.rb |  41 ++++++++++++++++++++-
 src/drc/unit_tests/drcSimpleTests.cc       |   5 +++
 testdata/algo/dss_sparse_array.gds         | Bin 0 -> 568 bytes
 testdata/algo/dss_sparse_array_au1.gds     | Bin 0 -> 1800 bytes
 testdata/drc/drcSimpleTests_148.drc        |  39 ++++++++++++++++++++
 testdata/drc/drcSimpleTests_148.gds        | Bin 0 -> 568 bytes
 testdata/drc/drcSimpleTests_au148d.gds     | Bin 0 -> 1800 bytes
 7 files changed, 84 insertions(+), 1 deletion(-)
 create mode 100644 testdata/algo/dss_sparse_array.gds
 create mode 100644 testdata/algo/dss_sparse_array_au1.gds
 create mode 100644 testdata/drc/drcSimpleTests_148.drc
 create mode 100644 testdata/drc/drcSimpleTests_148.gds
 create mode 100644 testdata/drc/drcSimpleTests_au148d.gds

diff --git a/src/drc/drc/built-in-macros/_drc_engine.rb b/src/drc/drc/built-in-macros/_drc_engine.rb
index e2ff2b7ee..fb331bc86 100644
--- a/src/drc/drc/built-in-macros/_drc_engine.rb
+++ b/src/drc/drc/built-in-macros/_drc_engine.rb
@@ -197,10 +197,11 @@ module DRC
       @total_timer = nil
       @drc_progress = nil
       
-      # initialize the defaults for max_area_ratio, max_vertex_count
+      # initialize the defaults for max_area_ratio, max_vertex_count, sparse_array_limit
       dss = RBA::DeepShapeStore::new
       @max_area_ratio = dss.max_area_ratio
       @max_vertex_count = dss.max_vertex_count
+      @sparse_array_limit = dss.sparse_array_limit
       @deep_reject_odd_polygons = dss.reject_odd_polygons
       dss._destroy
 
@@ -1309,6 +1310,43 @@ module DRC
       self.max_vertex_count(count)
     end
 
+    # %DRC%
+    # @name sparse_array_limit
+    # @brief Gets or sets the sparse array singularization limit
+    # @synopsis sparse_array_limit(limit)
+    # @synopsis sparse_array_limit
+    #
+    # In deep mode, array instances with a bad ratio of overall bounding box area
+    # vs. actually covered area, induce a performance penalty, because their bounding
+    # box is not longer a good approximation for their footprint.
+    # The "sparse array limit" defines the ratio of array instance bounding box area
+    # vs. sum of bounding box areas of the individual instances, above which the array
+    # is resolved into single instances.
+    #
+    # Use this method without an argument to get the current value.
+    #
+    # By default, this feature is off (the sparse array limit value is negative). 
+    # If your design uses many arrays with a bad coverage, you can set the sparse
+    # array limit to a value of 10 for example.
+ 
+    def sparse_array_limit(sal = nil)
+      if sal
+        if @dss
+          raise("sparse_array_limit must be set before the first 'input' statement in deep mode")
+        end
+        if sal.is_a?(1.0.class) || sal.is_a?(1.class)
+          @sparse_array_limit = sal
+        else
+          raise("Argument is not numerical in sparse_array_limit")
+        end
+      end
+      @sparse_array_limit
+    end
+
+    def sparse_array_limit=(sal)
+      self.sparse_array_limit(sal)
+    end
+
     # %DRC%
     # @name max_area_ratio
     # @brief Gets or sets the maximum bounding box to polygon area ratio for deep mode fragmentation
@@ -3305,6 +3343,7 @@ CODE
           @dss.reject_odd_polygons = @deep_reject_odd_polygons
           @dss.max_vertex_count = @max_vertex_count
           @dss.max_area_ratio = @max_area_ratio
+          @dss.sparse_array_limit = @sparse_array_limit
 
           r = cls.new(iter, @dss, RBA::ICplxTrans::new(sf.to_f))
 
diff --git a/src/drc/unit_tests/drcSimpleTests.cc b/src/drc/unit_tests/drcSimpleTests.cc
index 5efe37ba9..2d6db90f1 100644
--- a/src/drc/unit_tests/drcSimpleTests.cc
+++ b/src/drc/unit_tests/drcSimpleTests.cc
@@ -2108,3 +2108,8 @@ TEST(147_MeasureNetsWithL2N)
   compare_text_files (output, au_output);
 }
 
+TEST(148_sparse_array_limit)
+{
+  run_test (_this, "148", true);
+}
+
diff --git a/testdata/algo/dss_sparse_array.gds b/testdata/algo/dss_sparse_array.gds
new file mode 100644
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diff --git a/testdata/algo/dss_sparse_array_au1.gds b/testdata/algo/dss_sparse_array_au1.gds
new file mode 100644
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diff --git a/testdata/drc/drcSimpleTests_148.drc b/testdata/drc/drcSimpleTests_148.drc
new file mode 100644
index 000000000..b70e96436
--- /dev/null
+++ b/testdata/drc/drcSimpleTests_148.drc
@@ -0,0 +1,39 @@
+
+# Breaking
+
+source($drc_test_source, "TOP")
+target($drc_test_target)
+
+sparse_array_limit(10.0)
+if sparse_array_limit != 10.0
+  raise("sparse array limit is not 10.0!")
+end
+
+deep
+
+# can still set sparse_array_limit before the first input statement
+self.sparse_array_limit = 5.0
+if self.sparse_array_limit != 5.0
+  raise("sparse array limit is not 5.0!")
+end
+
+l1 = input(1, 0)
+l2 = input(2, 0)
+
+error = false
+begin
+  self.sparse_array_limit = 2.0
+rescue
+  error = true
+end
+error || raise("sparse_array_limit must throw an exception after 'deep'")
+
+if @dss.sparse_array_limit != 5.0
+  raise("sparse array limit of DSS is not 5.0!")
+end
+
+l1.output(1, 0)
+l2.output(2, 0)
+l1.sized(1.um).output(11, 0)
+l2.sized(1.um).output(12, 0)
+
diff --git a/testdata/drc/drcSimpleTests_148.gds b/testdata/drc/drcSimpleTests_148.gds
new file mode 100644
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GIT binary patch
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diff --git a/testdata/drc/drcSimpleTests_au148d.gds b/testdata/drc/drcSimpleTests_au148d.gds
new file mode 100644
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GIT binary patch
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