Add async2sync pass

Signed-off-by: Clifford Wolf <clifford@clifford.at>

2 files changed, 148 insertions, 0 deletions

diff --git a/passes/sat/Makefile.inc b/passes/sat/Makefile.inc
index 4fcce2fad..8ab0280c0 100644
--- a/passes/sat/Makefile.inc
+++ b/passes/sat/Makefile.inc
@@ -7,4 +7,5 @@ OBJS += passes/sat/miter.o
 OBJS += passes/sat/expose.o
 OBJS += passes/sat/assertpmux.o
 OBJS += passes/sat/clk2fflogic.o
+OBJS += passes/sat/async2sync.o
 
diff --git a/passes/sat/async2sync.cc b/passes/sat/async2sync.cc
new file mode 100644
index 000000000..85933acc2
--- /dev/null
+++ b/passes/sat/async2sync.cc
@@ -0,0 +1,147 @@
+/*
+ *  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 Async2syncPass : public Pass {
+	Async2syncPass() : Pass("async2sync", "convert async FF inputs to sync circuits") { }
+	virtual void help()
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    async2sync [options] [selection]\n");
+		log("\n");
+		log("This command replaces async FF inputs with sync circuits emulating the same\n");
+		log("behavior for when the async signals are actually synchronized to the clock.\n");
+		log("\n");
+		log("This pass assumes negative hold time for the async FF inputs. For example when\n");
+		log("a reset deasserts with the clock edge, then the FF output will still drive the\n");
+		log("reset value in the next cycle regardless of the data-in value at the time of\n");
+		log("the clock edge.\n");
+		log("\n");
+		log("Currently only $adff cells are supported by this pass.\n");
+		log("\n");
+	}
+	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
+	{
+		// bool flag_noinit = false;
+
+		log_header(design, "Executing ASYNC2SYNC pass.\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			// if (args[argidx] == "-noinit") {
+			// 	flag_noinit = true;
+			// 	continue;
+			// }
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		for (auto module : design->selected_modules())
+		{
+			SigMap sigmap(module);
+			dict<SigBit, State> initbits;
+			pool<SigBit> del_initbits;
+
+			for (auto wire : module->wires())
+				if (wire->attributes.count("\\init") > 0)
+				{
+					Const initval = wire->attributes.at("\\init");
+					SigSpec initsig = sigmap(wire);
+
+					for (int i = 0; i < GetSize(initval) && i < GetSize(initsig); i++)
+						if (initval[i] == State::S0 || initval[i] == State::S1)
+							initbits[initsig[i]] = initval[i];
+				}
+
+			for (auto cell : vector<Cell*>(module->selected_cells()))
+			{
+				if (cell->type.in("$adff"))
+				{
+					// bool clk_pol = cell->parameters["\\CLK_POLARITY"].as_bool();
+					bool arst_pol = cell->parameters["\\ARST_POLARITY"].as_bool();
+					Const arst_val = cell->parameters["\\ARST_VALUE"];
+
+					SigSpec sig_clk = cell->getPort("\\CLK");
+					SigSpec sig_arst = cell->getPort("\\ARST");
+					SigSpec sig_d = cell->getPort("\\D");
+					SigSpec sig_q = cell->getPort("\\Q");
+
+					log("Replacing %s.%s (%s): ARST=%s, D=%s, Q=%s\n",
+							log_id(module), log_id(cell), log_id(cell->type),
+							log_signal(sig_arst), log_signal(sig_d), log_signal(sig_q));
+
+					Const init_val;
+					for (int i = 0; i < GetSize(sig_q); i++) {
+						SigBit bit = sigmap(sig_q[i]);
+						init_val.bits.push_back(initbits.count(bit) ? initbits.at(bit) : State::Sx);
+						del_initbits.insert(bit);
+					}
+
+					Wire *new_d = module->addWire(NEW_ID, GetSize(sig_d));
+					Wire *new_q = module->addWire(NEW_ID, GetSize(sig_q));
+					new_q->attributes["\\init"] = init_val;
+
+					if (arst_pol) {
+						module->addMux(NEW_ID, sig_d, arst_val, sig_arst, new_d);
+						module->addMux(NEW_ID, new_q, arst_val, sig_arst, sig_q);
+					} else {
+						module->addMux(NEW_ID, arst_val, sig_d, sig_arst, new_d);
+						module->addMux(NEW_ID, arst_val, new_q, sig_arst, sig_q);
+					}
+
+					cell->setPort("\\D", new_d);
+					cell->setPort("\\Q", new_q);
+					cell->unsetPort("\\ARST");
+					cell->unsetParam("\\ARST_POLARITY");
+					cell->unsetParam("\\ARST_VALUE");
+					cell->type = "$dff";
+					continue;
+				}
+			}
+
+			for (auto wire : module->wires())
+				if (wire->attributes.count("\\init") > 0)
+				{
+					bool delete_initattr = true;
+					Const initval = wire->attributes.at("\\init");
+					SigSpec initsig = sigmap(wire);
+
+					for (int i = 0; i < GetSize(initval) && i < GetSize(initsig); i++)
+						if (del_initbits.count(initsig[i]) > 0)
+							initval[i] = State::Sx;
+						else if (initval[i] != State::Sx)
+							delete_initattr = false;
+
+					if (delete_initattr)
+						wire->attributes.erase("\\init");
+					else
+						wire->attributes.at("\\init") = initval;
+				}
+		}
+	}
+} Async2syncPass;
+
+PRIVATE_NAMESPACE_END