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diff --git a/passes/techmap/deminout.cc b/passes/techmap/deminout.cc
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+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "kernel/yosys.h"
+#include "kernel/sigtools.h"
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+struct DeminoutPass : public Pass {
+	DeminoutPass() : Pass("deminout", "demote inout ports to input or output") { }
+	virtual void help()
+	{
+		log("\n");
+		log("    deminout [options] [selection]\n");
+		log("\n");
+		log("\"Demote\" inout ports to input or output ports, if possible.\n");
+		log("\n");
+	}
+	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
+	{
+		log_header(design, "Executing DEMINOUT pass (demote inout ports to input or output).\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			// if (args[argidx] == "-bits") {
+			// 	flag_bits = true;
+			// 	continue;
+			// }
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		bool keep_running = true;
+
+		while (keep_running)
+		{
+			keep_running = false;
+
+			for (auto module : design->selected_modules())
+			{
+				SigMap sigmap(module);
+				pool<SigBit> bits_written, bits_used, bits_inout;
+				dict<SigBit, int> bits_numports;
+
+				for (auto wire : module->wires())
+					if (wire->port_id)
+						for (auto bit : sigmap(wire))
+							bits_numports[bit]++;
+
+				for (auto cell : module->cells())
+				for (auto &conn : cell->connections())
+				{
+					bool cellport_out = cell->output(conn.first) || !cell->known();
+					bool cellport_in = cell->input(conn.first) || !cell->known();
+
+					if (cellport_out && cellport_in)
+						for (auto bit : sigmap(conn.second))
+							bits_inout.insert(bit);
+
+					if (cellport_out)
+						for (auto bit : sigmap(conn.second))
+							bits_written.insert(bit);
+
+					if (cellport_in)
+						for (auto bit : sigmap(conn.second))
+							bits_used.insert(bit);
+				}
+
+				for (auto wire : module->selected_wires())
+					if (wire->port_input && wire->port_output)
+					{
+						bool new_input = false;
+						bool new_output = false;
+
+						for (auto bit : sigmap(wire))
+						{
+							if (bits_numports[bit] > 1 || bits_inout.count(bit))
+								new_input = true, new_output = true;
+
+							if (bits_written.count(bit))
+								new_output = true;
+							else if (bits_used.count(bit))
+								new_input = true;
+						}
+
+						if (new_input != new_output) {
+							log("Demoting inout port %s.%s to %s.\n", log_id(module), log_id(wire), new_input ? "input" : "output");
+							wire->port_input = new_input;
+							wire->port_output = new_output;
+							keep_running = true;
+						}
+					}
+			}
+		}
+	}
+} DeminoutPass;
+
+PRIVATE_NAMESPACE_END