From e8c26f2839611f5b52c29f711670888b02066064 Mon Sep 17 00:00:00 2001
From: Eddie Hung <eddie@fpgeh.com>
Date: Thu, 11 Apr 2019 15:52:04 -0700
Subject: [PATCH] WIP

---
 passes/techmap/Makefile.inc   |  1 +
 passes/techmap/pmux2shiftx.cc | 88 +++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+)
 create mode 100644 passes/techmap/pmux2shiftx.cc

diff --git a/passes/techmap/Makefile.inc b/passes/techmap/Makefile.inc
index cf9e198ad..81df499da 100644
--- a/passes/techmap/Makefile.inc
+++ b/passes/techmap/Makefile.inc
@@ -37,6 +37,7 @@ OBJS += passes/techmap/attrmap.o
 OBJS += passes/techmap/zinit.o
 OBJS += passes/techmap/dff2dffs.o
 OBJS += passes/techmap/flowmap.o
+OBJS += passes/techmap/pmux2shiftx.o
 endif
 
 GENFILES += passes/techmap/techmap.inc
diff --git a/passes/techmap/pmux2shiftx.cc b/passes/techmap/pmux2shiftx.cc
new file mode 100644
index 000000000..6569f995f
--- /dev/null
+++ b/passes/techmap/pmux2shiftx.cc
@@ -0,0 +1,88 @@
+/*
+ *  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
+			const int s_width = cell->getParam("\\S_WIDTH").as_int();
+			const int width = cell->getParam("\\WIDTH").as_int();
+			const int clog2width = ceil(log2(s_width));
+			RTLIL::SigSpec shiftx_a;
+			RTLIL::SigSpec pmux_a;
+			RTLIL::SigSpec pmux_b;
+            RTLIL::SigSpec b_port = cell->getPort("\\B");
+			if (!cell->getPort("\\A").is_fully_undef()) {
+                pmux_a = RTLIL::Const(RTLIL::S0, clog2width);
+                shiftx_a.append(cell->getPort("\\A"));
+                for (int i = s_width; i > 0; i--) {
+                    shiftx_a.append(b_port.extract((i-1)*width, width));
+                    pmux_b.append(RTLIL::Const(i, clog2width));
+                }
+
+            }
+            else {
+                pmux_a = RTLIL::Const(RTLIL::Sx, clog2width);
+                for (int i = s_width-1; i >= 0; i--) {
+                    shiftx_a.append(b_port.extract(i*width, width));
+                    pmux_b.append(RTLIL::Const(i, clog2width));
+                }
+            }
+			RTLIL::SigSpec pmux_y = module->addWire(NEW_ID, clog2width);
+			RTLIL::SigSpec shiftx_s = module->addWire(NEW_ID, 1 << clog2width);
+			module->addPmux(NEW_ID, pmux_a, pmux_b, cell->getPort("\\S"), pmux_y);
+			module->addShiftx(NEW_ID, shiftx_a, pmux_y, cell->getPort("\\Y"));
+			module->remove(cell);
+		}
+	}
+} Pmux2ShiftxPass;
+
+PRIVATE_NAMESPACE_END
-- 
2.30.2