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diff --git a/passes/techmap/demuxmap.cc b/passes/techmap/demuxmap.cc
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+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2022  Marcelina Kościelnicka <mwk@0x04.net>
+ *
+ *  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 DemuxmapPass : public Pass {
+	DemuxmapPass() : Pass("demuxmap", "transform $demux cells to $eq + $mux cells") { }
+	void help() override
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    demuxmap [selection]\n");
+		log("\n");
+		log("This pass transforms $demux cells to a bunch of equality comparisons.\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) override
+	{
+		log_header(design, "Executing DEMUXMAP pass.\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++) {
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		for (auto module : design->selected_modules())
+		for (auto cell : module->selected_cells())
+		{
+			if (cell->type != ID($demux))
+				continue;
+
+			SigSpec sel = cell->getPort(ID::S);
+			SigSpec data = cell->getPort(ID::A);
+			SigSpec out = cell->getPort(ID::Y);
+			int width = GetSize(cell->getPort(ID::A));
+
+			for (int i = 0; i < 1 << GetSize(sel); i++) {
+				if (width == 1 && data == State::S1) {
+					RTLIL::Cell *eq_cell = module->addEq(NEW_ID, sel, Const(i, GetSize(sel)), out[i]);
+					eq_cell->add_strpool_attribute(ID::src, cell->get_strpool_attribute(ID::src));
+				} else {
+					Wire *eq = module->addWire(NEW_ID);
+					RTLIL::Cell *eq_cell = module->addEq(NEW_ID, sel, Const(i, GetSize(sel)), eq);
+					eq_cell->add_strpool_attribute(ID::src, cell->get_strpool_attribute(ID::src));
+					RTLIL::Cell *mux = module->addMux(NEW_ID,
+							Const(State::S0, width),
+							data,
+							eq,
+							out.extract(i*width, width));
+					mux->add_strpool_attribute(ID::src, cell->get_strpool_attribute(ID::src));
+				}
+			}
+
+			module->remove(cell);
+		}
+	}
+} DemuxmapPass;
+
+PRIVATE_NAMESPACE_END