Various modifications to accommodate the somewhat complicated
management of include statements in verilog files in order to
build the compiled libraries.
diff --git a/sky130/custom/scripts/inc_verilog.py b/sky130/custom/scripts/inc_verilog.py
new file mode 100755
index 0000000..d34129d
--- /dev/null
+++ b/sky130/custom/scripts/inc_verilog.py
@@ -0,0 +1,110 @@
+#!/bin/env python3
+#
+# inc_verilog ---
+#
+# This script handles the verilog sources by removing `include statements
+# for files that are already being added to the single consolidated
+# verilog library file, and in-lining any other verilog files (namely
+# the functional and behavioral sources).
+#
+# This script is a filter to be run by setting the name of this script as
+# the value to "filter=" for the model install in the sky130 Makefile.
+
+import re
+import os
+import sys
+
+def filter(inname, outname):
+
+    # Read input
+    try:
+        with open(inname, 'r') as inFile:
+            vtext = inFile.read()
+            vlines = vtext.splitlines()
+    except:
+        print('inc_verilog.py: failed to open ' + fnmIn + ' for reading.', file=sys.stderr)
+        return 1
+
+    # Process input with regexp
+
+    fixedlines = []
+    modified = False
+    increx = re.compile('[ \t]*`include[ \t]+"?([^ \t\n"]+)"?')
+    ddotrex = re.compile('[^\.]+\.[^\.]+\.v')
+    tdotrex = re.compile('[^\.]+\.[^\.]+\.[^\.]+\.v')
+    inpath = os.path.split(inname)[0]
+
+    for line in vlines:
+
+        # Check includes
+        imatch = increx.match(line)
+        if imatch:
+            incfilename = imatch.group(1)
+            dmatch = ddotrex.match(incfilename)
+            tmatch = tdotrex.match(incfilename)
+            if dmatch or tmatch:
+                # double-dot or triple-dot:  Include this file in-line
+                # NOTE:  These files are assumed not to need in-line
+                # includes, but includes of primitives need to be ignored.
+
+                with open(inpath + '/' + incfilename, 'r') as incfile:
+                    v2text = incfile.read()
+                    v2lines = v2text.splitlines()
+                    for line2 in v2lines:
+                        i2match = imatch.match(line2)
+                        if not i2match:
+                            fixedlines.append(line2)
+            else:
+                # single-dot:  Ignore this line
+                pass
+            modified = True
+        else:
+            fixedlines.append(line)
+
+    # Write output
+    if outname == None:
+        for i in fixedlines:
+            print(i)
+    else:
+        # If the output is a symbolic link but no modifications have been made,
+        # then leave it alone.  If it was modified, then remove the symbolic
+        # link before writing.
+        if os.path.islink(outname):
+            if not modified:
+                return 0
+            else:
+                os.unlink(outname)
+        try:
+            with open(outname, 'w') as outFile:
+                for i in fixedlines:
+                    print(i, file=outFile)
+        except:
+            print('inc_verilog.py: failed to open ' + outname + ' for writing.', file=sys.stderr)
+            return 1
+
+
+if __name__ == '__main__':
+
+    # This script expects to get one or two arguments.  One argument is
+    # mandatory and is the input file.  The other argument is optional and
+    # is the output file.  The output file and input file may be the same
+    # name, in which case the original input is overwritten.
+
+    options = []
+    arguments = []
+    for item in sys.argv[1:]:
+        if item.find('-', 0) == 0:
+            options.append(item[1:])
+        else:
+            arguments.append(item)
+
+    if len(arguments) > 0:
+        infilename = arguments[0]
+
+    if len(arguments) > 1:
+        outfilename = arguments[1]
+    else:
+        outfilename = None
+
+    result = filter(infilename, outfilename)
+    sys.exit(result)