From 1bf8c2b823992569830cf0d248cb12bfccd5f384 Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Fri, 19 Apr 2019 14:03:05 +0200
Subject: [PATCH] Import initial pmux2shiftx from eddieh

Signed-off-by: Clifford Wolf <clifford@clifford.at>
---
 passes/opt/Makefile.inc   |  1 +
 passes/opt/pmux2shiftx.cc | 81 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)
 create mode 100644 passes/opt/pmux2shiftx.cc

diff --git a/passes/opt/Makefile.inc b/passes/opt/Makefile.inc
index c3e0a2a40..337fee9e4 100644
--- a/passes/opt/Makefile.inc
+++ b/passes/opt/Makefile.inc
@@ -13,5 +13,6 @@ OBJS += passes/opt/wreduce.o
 OBJS += passes/opt/opt_demorgan.o
 OBJS += passes/opt/rmports.o
 OBJS += passes/opt/opt_lut.o
+OBJS += passes/opt/pmux2shiftx.o
 endif
 
diff --git a/passes/opt/pmux2shiftx.cc b/passes/opt/pmux2shiftx.cc
new file mode 100644
index 000000000..6ffc27a4c
--- /dev/null
+++ b/passes/opt/pmux2shiftx.cc
@@ -0,0 +1,81 @@
+/*
+ *  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 Pmux2ShiftxPass : public Pass {
+	Pmux2ShiftxPass() : Pass("pmux2shiftx", "transform $pmux cells to $shiftx cells") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    pmux2shiftx [selection]\n");
+		log("\n");
+		log("This pass transforms $pmux cells to $shiftx cells.\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		log_header(design, "Executing PMUX2SHIFTX pass.\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++) {
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		for (auto module : design->selected_modules())
+		for (auto cell : module->selected_cells())
+		{
+			if (cell->type != "$pmux")
+				continue;
+
+			// Create a new encoder, out of a $pmux, that takes
+			// the existing pmux's 'S' input and transforms it
+			// back into a binary value
+			RTLIL::SigSpec shiftx_a;
+			RTLIL::SigSpec pmux_s;
+
+			int s_width = cell->getParam("\\S_WIDTH").as_int();
+			if (!cell->getPort("\\A").is_fully_undef()) {
+				++s_width;
+				shiftx_a.append(cell->getPort("\\A"));
+				pmux_s.append(module->Not(NEW_ID, module->ReduceOr(NEW_ID, cell->getPort("\\S"))));
+			}
+			const int clog2width = ceil(log2(s_width));
+
+			RTLIL::SigSpec pmux_b;
+			for (int i = s_width-1; i >= 0; i--)
+				pmux_b.append(RTLIL::Const(i, clog2width));
+			shiftx_a.append(cell->getPort("\\B"));
+			pmux_s.append(cell->getPort("\\S"));
+
+			RTLIL::SigSpec pmux_y = module->addWire(NEW_ID, clog2width);
+			module->addPmux(NEW_ID, RTLIL::Const(RTLIL::Sx, clog2width), pmux_b, pmux_s, pmux_y);
+			module->addShiftx(NEW_ID, shiftx_a, pmux_y, cell->getPort("\\Y"));
+			module->remove(cell);
+		}
+	}
+} Pmux2ShiftxPass;
+
+PRIVATE_NAMESPACE_END
-- 
2.30.2