Merge pull request #3203 from YosysHQ/micko/sim_ff

Simulation for various FF types

45 files changed, 1170 insertions, 172 deletions

diff --git a/Makefile b/Makefile
index eb2213898..c10a33803 100644
--- a/Makefile
+++ b/Makefile
@@ -803,6 +803,7 @@ test: $(TARGETS) $(EXTRA_TARGETS)
 	+cd tests/various && bash run-test.sh
 	+cd tests/select && bash run-test.sh
 	+cd tests/sat && bash run-test.sh
+	+cd tests/sim && bash run-test.sh
 	+cd tests/svinterfaces && bash run-test.sh $(SEEDOPT)
 	+cd tests/svtypes && bash run-test.sh $(SEEDOPT)
 	+cd tests/proc && bash run-test.sh
diff --git a/kernel/fstdata.cc b/kernel/fstdata.cc
index 330c4d189..1386a3300 100644
--- a/kernel/fstdata.cc
+++ b/kernel/fstdata.cc
@@ -109,8 +109,7 @@ void FstData::extractVarNames()
 				}
 				if (clean_name[0]=='\\')
 					clean_name = clean_name.substr(1);
-				//log("adding %s.%s\n",var.scope.c_str(), clean_name.c_str());
-				
+
 				name_to_handle[var.scope+"."+clean_name] = h->u.var.handle;
 				break;
 			}
@@ -118,48 +117,6 @@ void FstData::extractVarNames()
 	}
 }
 
-static void reconstruct_edges_varlen(void *user_data, uint64_t pnt_time, fstHandle pnt_facidx, const unsigned char *pnt_value, uint32_t plen)
-{
-	FstData *ptr = (FstData*)user_data;
-	ptr->reconstruct_edges_callback(pnt_time, pnt_facidx, pnt_value, plen);
-}
-
-static void reconstruct_edges(void *user_data, uint64_t pnt_time, fstHandle pnt_facidx, const unsigned char *pnt_value)
-{
-	FstData *ptr = (FstData*)user_data;
-	uint32_t plen = (pnt_value) ?  strlen((const char *)pnt_value) : 0;
-	ptr->reconstruct_edges_callback(pnt_time, pnt_facidx, pnt_value, plen);
-}
-
-void FstData::reconstruct_edges_callback(uint64_t pnt_time, fstHandle pnt_facidx, const unsigned char *pnt_value, uint32_t /* plen */)
-{
-	std::string val = std::string((const char *)pnt_value);
-	std::string prev = last_data[pnt_facidx];
-	if (pnt_time>=start_time) {
-		if (prev!="1" && val=="1")
-			edges.push_back(pnt_time);
-		if (prev!="0" && val=="0")
-			edges.push_back(pnt_time);
-	}
-	last_data[pnt_facidx] = val;
-}
-
-std::vector<uint64_t> FstData::getAllEdges(std::vector<fstHandle> &signal, uint64_t start, uint64_t end)
-{
-	start_time = start;
-	end_time = end;
-	last_data.clear();
-	for(auto &s : signal) {
-		last_data[s] = "x";
-	}
-	edges.clear();
-	fstReaderSetLimitTimeRange(ctx, start_time, end_time);
-	fstReaderClrFacProcessMaskAll(ctx);
-	for(const auto sig : signal)
-		fstReaderSetFacProcessMask(ctx,sig);
-	fstReaderIterBlocks2(ctx, reconstruct_edges, reconstruct_edges_varlen, this, nullptr);
-	return edges;
-}
 
 static void reconstruct_clb_varlen_attimes(void *user_data, uint64_t pnt_time, fstHandle pnt_facidx, const unsigned char *pnt_value, uint32_t plen)
 {
@@ -176,77 +133,65 @@ static void reconstruct_clb_attimes(void *user_data, uint64_t pnt_time, fstHandl
 
 void FstData::reconstruct_callback_attimes(uint64_t pnt_time, fstHandle pnt_facidx, const unsigned char *pnt_value, uint32_t /* plen */)
 {
-	if (sample_times_ndx >= sample_times.size()) return;
-
-	uint64_t time = sample_times[sample_times_ndx];
+	if (pnt_time > end_time) return;
 	// if we are past the timestamp
-	if (pnt_time > time) {
-		for (auto const& c : last_data)
-		{
-			handle_to_data[c.first].push_back(std::make_pair(time,c.second));
-			size_t index = handle_to_data[c.first].size() - 1;
-			time_to_index[c.first][time] = index;
+	bool is_clock = false;
+	if (!all_samples) {
+		for(auto &s : clk_signals) {
+			if (s==pnt_facidx)  { 
+				is_clock=true;
+				break;
+			}
 		}
-		sample_times_ndx++;
 	}
-	// always update last_data
-	last_data[pnt_facidx] =  std::string((const char *)pnt_value);
-}
 
-void FstData::reconstructAtTimes(std::vector<fstHandle> &signal, std::vector<uint64_t> time)
-{
-	handle_to_data.clear();
-	time_to_index.clear();
-	last_data.clear();
-	sample_times_ndx = 0;
-	sample_times = time;
-	fstReaderSetUnlimitedTimeRange(ctx);
-	fstReaderClrFacProcessMaskAll(ctx);
-	for(const auto sig : signal)
-		fstReaderSetFacProcessMask(ctx,sig);
-	fstReaderIterBlocks2(ctx, reconstruct_clb_attimes, reconstruct_clb_varlen_attimes, this, nullptr);
+	if (pnt_time > past_time) {
+		past_data = last_data;
+		past_time = pnt_time;
+	}
 
-	if (time_to_index[signal.back()].count(time.back())==0) {
-		for (auto const& c : last_data)
-		{
-			handle_to_data[c.first].push_back(std::make_pair(time.back(),c.second));
-			size_t index = handle_to_data[c.first].size() - 1;
-			time_to_index[c.first][time.back()] = index;
+	if (pnt_time > last_time) {
+		if (all_samples) {
+			callback(last_time);
+			last_time = pnt_time;
+		} else {
+			if (is_clock) {
+				std::string val = std::string((const char *)pnt_value);
+				std::string prev = past_data[pnt_facidx];
+				if ((prev!="1" && val=="1") || (prev!="0" && val=="0")) {
+					callback(last_time);
+					last_time = pnt_time;
+				}
+			}
 		}
 	}
+	// always update last_data
+	last_data[pnt_facidx] =  std::string((const char *)pnt_value);
 }
 
-void FstData::reconstructAllAtTimes(std::vector<uint64_t> time)
+void FstData::reconstructAllAtTimes(std::vector<fstHandle> &signal, uint64_t start, uint64_t end, CallbackFunction cb)
 {
-	handle_to_data.clear();
-	time_to_index.clear();
+	clk_signals = signal;
+	callback = cb;
+	start_time = start;
+	end_time = end;
 	last_data.clear();
-	sample_times_ndx = 0;
-	sample_times = time;
+	last_time = start_time;
+	past_data.clear();
+	past_time = start_time;
+	all_samples = clk_signals.empty();
 
 	fstReaderSetUnlimitedTimeRange(ctx);
 	fstReaderSetFacProcessMaskAll(ctx);
 	fstReaderIterBlocks2(ctx, reconstruct_clb_attimes, reconstruct_clb_varlen_attimes, this, nullptr);
-
-	if (time_to_index[1].count(time.back())==0) {
-		for (auto const& c : last_data)
-		{
-			handle_to_data[c.first].push_back(std::make_pair(time.back(),c.second));
-			size_t index = handle_to_data[c.first].size() - 1;
-			time_to_index[c.first][time.back()] = index;
-		}
-	}
+	callback(last_time);
+	if (last_time!=end_time)
+		callback(end_time);
 }
 
-std::string FstData::valueAt(fstHandle signal, uint64_t time)
+std::string FstData::valueOf(fstHandle signal)
 {
-	if (handle_to_data.find(signal) == handle_to_data.end())
+	if (past_data.find(signal) == past_data.end())
 		log_error("Signal id %d not found\n", (int)signal);
-	auto &data = handle_to_data[signal];
-	if (time_to_index[signal].count(time)!=0) {
-		size_t index = time_to_index[signal][time];
-		return data.at(index).second;
-	} else {
-		log_error("No data for signal %d at time %d\n", (int)signal, (int)time);
-	}
+	return past_data[signal];
 }
diff --git a/kernel/fstdata.h b/kernel/fstdata.h
index c069ff5e5..707d1b64e 100644
--- a/kernel/fstdata.h
+++ b/kernel/fstdata.h
@@ -25,6 +25,9 @@
 
 YOSYS_NAMESPACE_BEGIN
 
+typedef std::function<void(uint64_t)> CallbackFunction;
+struct fst_end_of_data_exception { };
+
 struct FstVar
 {
 	fstHandle id;
@@ -45,14 +48,10 @@ class FstData
 
 	std::vector<FstVar>& getVars() { return vars; };
 
-	void reconstruct_edges_callback(uint64_t pnt_time, fstHandle pnt_facidx, const unsigned char *pnt_value, uint32_t plen);
-	std::vector<uint64_t> getAllEdges(std::vector<fstHandle> &signal, uint64_t start_time, uint64_t end_time);
-
 	void reconstruct_callback_attimes(uint64_t pnt_time, fstHandle pnt_facidx, const unsigned char *pnt_value, uint32_t plen);
-	void reconstructAtTimes(std::vector<fstHandle> &signal,std::vector<uint64_t> time);
-	void reconstructAllAtTimes(std::vector<uint64_t> time);
+	void reconstructAllAtTimes(std::vector<fstHandle> &signal, uint64_t start_time, uint64_t end_time, CallbackFunction cb);
 
-	std::string valueAt(fstHandle signal, uint64_t time);
+	std::string valueOf(fstHandle signal);
 	fstHandle getHandle(std::string name);
 	double getTimescale() { return timescale; }
 	const char *getTimescaleString() { return timescale_str.c_str(); }
@@ -64,16 +63,17 @@ private:
 	std::vector<FstVar> vars;
 	std::map<fstHandle, FstVar> handle_to_var;
 	std::map<std::string, fstHandle> name_to_handle;
-	std::map<fstHandle, std::vector<std::pair<uint64_t, std::string>>> handle_to_data;
 	std::map<fstHandle, std::string> last_data;
-	std::map<fstHandle, std::map<uint64_t, size_t>> time_to_index;
-	std::vector<uint64_t> sample_times;
-	size_t sample_times_ndx;
+	uint64_t last_time;
+	std::map<fstHandle, std::string> past_data;
+	uint64_t past_time;
 	double timescale;
 	std::string timescale_str;
 	uint64_t start_time;
 	uint64_t end_time;
-	std::vector<uint64_t> edges;
+	CallbackFunction callback;
+	std::vector<fstHandle> clk_signals;
+	bool all_samples;
 };
 
 YOSYS_NAMESPACE_END
diff --git a/passes/sat/sim.cc b/passes/sat/sim.cc
index a7c109374..3b8114fa9 100644
--- a/passes/sat/sim.cc
+++ b/passes/sat/sim.cc
@@ -22,6 +22,7 @@
 #include "kernel/celltypes.h"
 #include "kernel/mem.h"
 #include "kernel/fstdata.h"
+#include "kernel/ff.h"
 
 #include <ctime>
 
@@ -113,8 +114,13 @@ struct SimInstance
 
 	struct ff_state_t
 	{
-		State past_clock;
 		Const past_d;
+		Const past_ad;
+		State past_clk;
+		State past_ce;
+		State past_srst;
+		
+		FfData data;
 	};
 
 	struct mem_state_t
@@ -209,10 +215,15 @@ struct SimInstance
 					}
 			}
 
-			if (cell->type.in(ID($dff))) {
+			if (RTLIL::builtin_ff_cell_types().count(cell->type)) {
+				FfData ff_data(nullptr, cell);
 				ff_state_t ff;
-				ff.past_clock = State::Sx;
-				ff.past_d = Const(State::Sx, cell->getParam(ID::WIDTH).as_int());
+				ff.past_d = Const(State::Sx, ff_data.width);
+				ff.past_ad = Const(State::Sx, ff_data.width);
+				ff.past_clk = State::Sx;
+				ff.past_ce = State::Sx;
+				ff.past_srst = State::Sx;
+				ff.data = ff_data;
 				ff_database[cell] = ff;
 			}
 
@@ -229,11 +240,10 @@ struct SimInstance
 		{
 			for (auto &it : ff_database)
 			{
-				Cell *cell = it.first;
 				ff_state_t &ff = it.second;
 				zinit(ff.past_d);
 
-				SigSpec qsig = cell->getPort(ID::Q);
+				SigSpec qsig = it.second.data.sig_q;
 				Const qdata = get_state(qsig);
 				zinit(qdata);
 				set_state(qsig, qdata);
@@ -466,21 +476,62 @@ struct SimInstance
 
 		for (auto &it : ff_database)
 		{
-			Cell *cell = it.first;
 			ff_state_t &ff = it.second;
-
-			if (cell->type.in(ID($dff)))
-			{
-				bool clkpol = cell->getParam(ID::CLK_POLARITY).as_bool();
-				State current_clock = get_state(cell->getPort(ID::CLK))[0];
-
-				if (clkpol ? (ff.past_clock == State::S1 || current_clock != State::S1) :
-						(ff.past_clock == State::S0 || current_clock != State::S0))
-					continue;
-
-				if (set_state(cell->getPort(ID::Q), ff.past_d))
-					did_something = true;
+			FfData &ff_data = ff.data;
+
+			Const current_q = get_state(ff.data.sig_q);
+
+			if (ff_data.has_clk) {
+				// flip-flops
+				State current_clk = get_state(ff_data.sig_clk)[0];
+				if (ff_data.pol_clk ? (ff.past_clk == State::S0 && current_clk != State::S0) :
+							(ff.past_clk == State::S1 && current_clk != State::S1)) {
+					bool ce = ff.past_ce == (ff_data.pol_ce ? State::S1 : State::S0);
+					// set if no ce, or ce is enabled
+					if (!ff_data.has_ce || (ff_data.has_ce && ce)) {
+						current_q = ff.past_d;
+					}
+					// override if sync reset
+					if ((ff_data.has_srst) && (ff.past_srst == (ff_data.pol_srst ? State::S1 : State::S0)) &&
+						((!ff_data.ce_over_srst) || (ff_data.ce_over_srst && ce))) {
+						current_q = ff_data.val_srst;
+					}
+				}
+			}
+			// async load
+			if (ff_data.has_aload) {
+				State current_aload = get_state(ff_data.sig_aload)[0];
+				if (current_aload == (ff_data.pol_aload ? State::S1 : State::S0)) {
+					current_q = ff_data.has_clk ? ff.past_ad : get_state(ff.data.sig_ad);
+				}
+			}
+			// async reset
+			if (ff_data.has_arst) {
+				State current_arst = get_state(ff_data.sig_arst)[0];
+				if (current_arst == (ff_data.pol_arst ? State::S1 : State::S0)) {
+					current_q = ff_data.val_arst;
+				}
+			}
+			// handle set/reset
+			if (ff.data.has_sr) {
+				Const current_clr = get_state(ff.data.sig_clr);
+				Const current_set = get_state(ff.data.sig_set);
+
+				for(int i=0;i<ff.past_d.size();i++) {
+					if (current_clr[i] == (ff_data.pol_clr ? State::S1 : State::S0)) {
+						current_q[i] = State::S0;
+					}
+					else if (current_set[i] == (ff_data.pol_set ? State::S1 : State::S0)) {
+						current_q[i] = State::S1;
+					}
+				}
+			}
+			if (ff_data.has_gclk) {
+				// $ff
+				current_q = ff.past_d;
 			}
+			if (set_state(ff_data.sig_q, current_q))
+				did_something = true;
 		}
 
 		for (auto &it : mem_database)
@@ -538,13 +589,22 @@ struct SimInstance
 	{
 		for (auto &it : ff_database)
 		{
-			Cell *cell = it.first;
 			ff_state_t &ff = it.second;
 
-			if (cell->type.in(ID($dff))) {
-				ff.past_clock = get_state(cell->getPort(ID::CLK))[0];
-				ff.past_d = get_state(cell->getPort(ID::D));
-			}
+			if (ff.data.has_aload)
+				ff.past_ad = get_state(ff.data.sig_ad);
+
+			if (ff.data.has_clk || ff.data.has_gclk)
+				ff.past_d = get_state(ff.data.sig_d);
+
+			if (ff.data.has_clk)
+				ff.past_clk = get_state(ff.data.sig_clk)[0];
+
+			if (ff.data.has_ce)
+				ff.past_ce = get_state(ff.data.sig_ce)[0];
+
+			if (ff.data.has_srst)
+				ff.past_srst = get_state(ff.data.sig_srst)[0];
 		}
 
 		for (auto &it : mem_database)
@@ -595,8 +655,7 @@ struct SimInstance
 
 		for (auto &it : ff_database)
 		{
-			Cell *cell = it.first;
-			SigSpec sig_q = cell->getPort(ID::Q);
+			SigSpec sig_q = it.second.data.sig_q;
 			Const initval = get_state(sig_q);
 
 			for (int i = 0; i < GetSize(sig_q); i++)
@@ -722,34 +781,32 @@ struct SimInstance
 			child.second->write_fst_step(f);
 	}
 
-	void setInitState(uint64_t time)
+	void setInitState()
 	{
 		for (auto &it : ff_database)
 		{
-			Cell *cell = it.first;
-			
-			SigSpec qsig = cell->getPort(ID::Q);
+			SigSpec qsig = it.second.data.sig_q;
 			if (qsig.is_wire()) {
 				IdString name = qsig.as_wire()->name;
 				fstHandle id = shared->fst->getHandle(scope + "." + RTLIL::unescape_id(name));
 				if (id==0 && name.isPublic())
 					log_warning("Unable to found wire %s in input file.\n", (scope + "." + RTLIL::unescape_id(name)).c_str());
 				if (id!=0) {
-					Const fst_val = Const::from_string(shared->fst->valueAt(id, time));
+					Const fst_val = Const::from_string(shared->fst->valueOf(id));
 					set_state(qsig, fst_val);
 				}
 			}
 		}
 		for (auto child : children)
-			child.second->setInitState(time);
+			child.second->setInitState();
 	}
 
-	bool checkSignals(uint64_t time)
+	bool checkSignals()
 	{
 		bool retVal = false;
 		for(auto &item : fst_handles) {
 			if (item.second==0) continue; // Ignore signals not found
-			Const fst_val = Const::from_string(shared->fst->valueAt(item.second, time));
+			Const fst_val = Const::from_string(shared->fst->valueOf(item.second));
 			Const sim_val = get_state(item.first);
 			if (sim_val.size()!=fst_val.size())
 				log_error("Signal '%s' size is different in gold and gate.\n", log_id(item.first));
@@ -779,7 +836,7 @@ struct SimInstance
 			}
 		}
 		for (auto child : children)
-			retVal |= child.second->checkSignals(time);
+			retVal |= child.second->checkSignals();
 		return retVal;
 	}
 };
@@ -998,8 +1055,6 @@ struct SimWorker : SimShared
 				log_error("Can't find port %s.%s in FST.\n", scope.c_str(), log_id(portname));
 			fst_clock.push_back(id);
 		}
-		if (fst_clock.size()==0)
-			log_error("No clock signals defined for input file\n");
 
 		SigMap sigmap(topmod);
 		std::map<Wire*,fstHandle> inputs;
@@ -1044,37 +1099,48 @@ struct SimWorker : SimShared
 		if (stopCount<startCount) {
 			log_error("Stop time is before start time\n");
 		}
-		auto samples = fst->getAllEdges(fst_clock, startCount, stopCount);
-
-		// Limit to number of cycles if provided
-		if (cycles_set && ((size_t)(numcycles *2) < samples.size()))
-			samples.erase(samples.begin() + (numcycles*2), samples.end());
-
-		// Add setup time (start time)
-		if (samples.empty() || samples.front()!=startCount)
-			samples.insert(samples.begin(), startCount);
 
-		fst->reconstructAllAtTimes(samples);
 		bool initial = true;
 		int cycle = 0;
-		log("Co-simulation from %lu%s to %lu%s\n", (unsigned long)startCount, fst->getTimescaleString(), (unsigned long)stopCount, fst->getTimescaleString());
-		for(auto &time : samples) {
-			log("Co-simulating cycle %d [%lu%s].\n", cycle, (unsigned long)time, fst->getTimescaleString());
-			for(auto &item : inputs) {
-				std::string v = fst->valueAt(item.second, time);
-				top->set_state(item.first, Const::from_string(v));
-			}
-			if (initial) {
-				top->setInitState(time);
-				initial = false;
-			}
-			update();
+		log("Co-simulation from %lu%s to %lu%s", (unsigned long)startCount, fst->getTimescaleString(), (unsigned long)stopCount, fst->getTimescaleString());
+		if (cycles_set) 
+			log(" for %d clock cycle(s)",numcycles);
+		log("\n");
+		bool all_samples = fst_clock.empty();
+
+		try {
+			fst->reconstructAllAtTimes(fst_clock, startCount, stopCount, [&](uint64_t time) {
+				log("Co-simulating %s %d [%lu%s].\n", (all_samples ? "sample" : "cycle"), cycle, (unsigned long)time, fst->getTimescaleString());
+				for(auto &item : inputs) {
+					std::string v = fst->valueOf(item.second);
+					top->set_state(item.first, Const::from_string(v));
+				}
 
-			bool status = top->checkSignals(time);
-			if (status)
-				log_error("Signal difference\n");
-			cycle++;
+				if (initial) {
+					top->setInitState();
+					write_output_header();
+					initial = false;
+				}
+				update();
+				write_output_step(5*cycle);
+
+				bool status = top->checkSignals();
+				if (status)
+					log_error("Signal difference\n");
+				cycle++;
+
+				// Limit to number of cycles if provided
+				if (cycles_set && cycle > numcycles *2)
+					throw fst_end_of_data_exception();
+				if (time==stopCount)
+					throw fst_end_of_data_exception();
+			});
+		} catch(fst_end_of_data_exception) {
+			// end of data detected
 		}
+		write_output_step(5*(cycle-1)+2);
+		write_output_end();
+
 		if (writeback) {
 			pool<Module*> wbmods;
 			top->writeback(wbmods);
diff --git a/tests/sim/.gitignore b/tests/sim/.gitignore
new file mode 100644
index 000000000..2c96b65f8
--- /dev/null
+++ b/tests/sim/.gitignore
@@ -0,0 +1,6 @@
+*.log
+/run-test.mk
++*_synth.v
++*_testbench
+*.out
+*.fst
diff --git a/tests/sim/adff.v b/tests/sim/adff.v
new file mode 100644
index 000000000..8c8fb0acf
--- /dev/null
+++ b/tests/sim/adff.v
@@ -0,0 +1,7 @@
+module adff( input d, clk, rst, output reg q );
+	always @( posedge clk, posedge rst )
+		if (rst)
+			q <= 0;
+		else
+			q <= d;
+endmodule
diff --git a/tests/sim/adffe.v b/tests/sim/adffe.v
new file mode 100644
index 000000000..55c7d8d4e
--- /dev/null
+++ b/tests/sim/adffe.v
@@ -0,0 +1,8 @@
+module adffe( input d, clk, rst, en, output reg q );
+	always @( posedge clk, posedge rst )
+		if (rst)
+			q <= 0;
+		else
+			if (en)
+				q <= d;
+endmodule
diff --git a/tests/sim/adlatch.v b/tests/sim/adlatch.v
new file mode 100644
index 000000000..5e8f48e49
--- /dev/null
+++ b/tests/sim/adlatch.v
@@ -0,0 +1,8 @@
+module adlatch( input d, rst, en, output reg q );
+	always @* begin
+		if (rst)
+			q = 0;
+		else if (en)
+			q = d;
+	end
+endmodule
diff --git a/tests/sim/aldff.v b/tests/sim/aldff.v
new file mode 100644
index 000000000..eeb0f0673
--- /dev/null
+++ b/tests/sim/aldff.v
@@ -0,0 +1,7 @@
+module aldff( input [0:3] d, input [0:3] ad, input clk, aload, output reg [0:3] q );
+	always @( posedge clk, posedge aload)
+		if (aload)
+			q <= ad;
+		else
+			q <= d;
+endmodule
diff --git a/tests/sim/aldffe.v b/tests/sim/aldffe.v
new file mode 100644
index 000000000..79c65afc4
--- /dev/null
+++ b/tests/sim/aldffe.v
@@ -0,0 +1,8 @@
+module aldffe( input [0:3] d, input [0:3] ad, input clk, aload, en, output reg [0:3] q );
+	always @( posedge clk, posedge aload)
+		if (aload)
+			q <= ad;
+		else
+			if (en)
+				q <= d;
+endmodule
diff --git a/tests/sim/dff.v b/tests/sim/dff.v
new file mode 100644
index 000000000..ce792b59a
--- /dev/null
+++ b/tests/sim/dff.v
@@ -0,0 +1,4 @@
+module dff( input d, clk, output reg q );
+	always @( posedge clk )
+		q <= d;
+endmodule
diff --git a/tests/sim/dffe.v b/tests/sim/dffe.v
new file mode 100644
index 000000000..853fcf66a
--- /dev/null
+++ b/tests/sim/dffe.v
@@ -0,0 +1,5 @@
+module dffe( input clk, en, d, output reg q );
+	always @( posedge clk )
+		if ( en )
+			q <= d;
+endmodule
diff --git a/tests/sim/dffsr.v b/tests/sim/dffsr.v
new file mode 100644
index 000000000..2158708f1
--- /dev/null
+++ b/tests/sim/dffsr.v
@@ -0,0 +1,9 @@
+module dffsr( input clk, d, clr, set, output reg q );
+	always @( posedge clk, posedge set, posedge clr)
+		if ( clr )
+			q <= 0;
+		else if (set)
+			q <= 1;
+		else
+			q <= d;
+endmodule
diff --git a/tests/sim/dlatch.v b/tests/sim/dlatch.v
new file mode 100644
index 000000000..315b43216
--- /dev/null
+++ b/tests/sim/dlatch.v
@@ -0,0 +1,6 @@
+module dlatch( input d, en, output reg q );
+	always @* begin
+		if ( en )
+			q = d;
+	end
+endmodule
diff --git a/tests/sim/dlatchsr.v b/tests/sim/dlatchsr.v
new file mode 100644
index 000000000..1d13ac2ad
--- /dev/null
+++ b/tests/sim/dlatchsr.v
@@ -0,0 +1,11 @@
+module dlatchsr( input d, set, clr, en, output reg q );
+	always @* begin
+		if ( clr )
+			q = 0;
+		else if (set)
+			q = 1;
+		else
+			if (en)
+				q = d;
+	end
+endmodule
diff --git a/tests/sim/run-test.sh b/tests/sim/run-test.sh
new file mode 100755
index 000000000..d34d1f3c9
--- /dev/null
+++ b/tests/sim/run-test.sh
@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+set -eu
+source ../gen-tests-makefile.sh
+echo "Generate FST for sim models"
+find tb/* -name tb*.v | while read name; do
+    test_name=$(basename -s .v $name)
+    echo "Test $test_name"
+    verilog_name=${test_name:3}.v
+    iverilog -o tb/$test_name.out $name $verilog_name
+    ./tb/$test_name.out -fst
+done
+run_tests --yosys-scripts --bash --yosys-args "-w 'Yosys has only limited support for tri-state logic at the moment.'"
diff --git a/tests/sim/sdff.v b/tests/sim/sdff.v
new file mode 100644
index 000000000..6b25516e1
--- /dev/null
+++ b/tests/sim/sdff.v
@@ -0,0 +1,7 @@
+module sdff( input d, clk, rst, output reg q );
+	always @( posedge clk)
+		if (rst)
+			q <= 0;
+		else
+			q <= d;
+endmodule
diff --git a/tests/sim/sdffce.v b/tests/sim/sdffce.v
new file mode 100644
index 000000000..7d27d5741
--- /dev/null
+++ b/tests/sim/sdffce.v
@@ -0,0 +1,8 @@
+module sdffce( input d, clk, rst, en, output reg q );
+	always @( posedge clk)
+		if(en)
+			if (rst)
+				q <= 0;
+			else
+				q <= d;
+endmodule
diff --git a/tests/sim/sdffe.v b/tests/sim/sdffe.v
new file mode 100644
index 000000000..0a96693e1
--- /dev/null
+++ b/tests/sim/sdffe.v
@@ -0,0 +1,8 @@
+module sdffe( input d, clk, rst, en, output reg q );
+	always @( posedge clk)
+		if (rst)
+			q <= 0;
+		else
+			if (en)
+				q <= d;
+endmodule
diff --git a/tests/sim/sim_adff.ys b/tests/sim/sim_adff.ys
new file mode 100644
index 000000000..6efd804a9
--- /dev/null
+++ b/tests/sim/sim_adff.ys
@@ -0,0 +1,6 @@
+read_verilog adff.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$adff
+sim -clock clk -r tb_adff.fst -scope tb_adff.uut -sim-cmp adff
diff --git a/tests/sim/sim_adffe.ys b/tests/sim/sim_adffe.ys
new file mode 100644
index 000000000..47a51ebce
--- /dev/null
+++ b/tests/sim/sim_adffe.ys
@@ -0,0 +1,6 @@
+read_verilog adffe.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$adffe
+sim -clock clk -r tb_adffe.fst -scope tb_adffe.uut -sim-cmp adffe
diff --git a/tests/sim/sim_adlatch.ys b/tests/sim/sim_adlatch.ys
new file mode 100644
index 000000000..eece7dc0d
--- /dev/null
+++ b/tests/sim/sim_adlatch.ys
@@ -0,0 +1,10 @@
+read_verilog -icells <<EOT
+module adlatch(input d, rst, en, output reg q);
+$adlatch #(.EN_POLARITY(1'b1), .ARST_POLARITY(1'b1), .ARST_VALUE(1'b0), .WIDTH(1)) uut (.EN(en), .ARST(rst), .D(d), .Q(q));
+endmodule
+EOT
+proc
+opt_dff
+stat
+select -assert-count 1 t:$adlatch
+sim -r tb_adlatch.fst -scope tb_adlatch.uut -sim-cmp adlatch
diff --git a/tests/sim/sim_aldff.ys b/tests/sim/sim_aldff.ys
new file mode 100644
index 000000000..9c8b3bdfc
--- /dev/null
+++ b/tests/sim/sim_aldff.ys
@@ -0,0 +1,6 @@
+read_verilog aldff.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$aldff
+sim -clock clk -r tb_aldff.fst -scope tb_aldff.uut -sim-cmp aldff
diff --git a/tests/sim/sim_aldffe.ys b/tests/sim/sim_aldffe.ys
new file mode 100644
index 000000000..b191cf877
--- /dev/null
+++ b/tests/sim/sim_aldffe.ys
@@ -0,0 +1,6 @@
+read_verilog aldffe.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$aldffe
+sim -clock clk -r tb_aldffe.fst -scope tb_aldffe.uut -sim-cmp aldffe
diff --git a/tests/sim/sim_dff.ys b/tests/sim/sim_dff.ys
new file mode 100644
index 000000000..12f402443
--- /dev/null
+++ b/tests/sim/sim_dff.ys
@@ -0,0 +1,6 @@
+read_verilog dff.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$dff
+sim -clock clk -r tb_dff.fst -scope tb_dff.uut -sim-cmp dff
diff --git a/tests/sim/sim_dffe.ys b/tests/sim/sim_dffe.ys
new file mode 100644
index 000000000..f9b9e4767
--- /dev/null
+++ b/tests/sim/sim_dffe.ys
@@ -0,0 +1,6 @@
+read_verilog dffe.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$dffe
+sim -clock clk -r tb_dffe.fst -scope tb_dffe.uut -sim-cmp dffe
diff --git a/tests/sim/sim_dffsr.ys b/tests/sim/sim_dffsr.ys
new file mode 100644
index 000000000..e99ee860d
--- /dev/null
+++ b/tests/sim/sim_dffsr.ys
@@ -0,0 +1,6 @@
+read_verilog dffsr.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$dffsr
+sim -clock clk -r tb_dffsr.fst -scope tb_dffsr.uut -sim-cmp dffsr
diff --git a/tests/sim/sim_dlatch.ys b/tests/sim/sim_dlatch.ys
new file mode 100644
index 000000000..79e4601e3
--- /dev/null
+++ b/tests/sim/sim_dlatch.ys
@@ -0,0 +1,6 @@
+read_verilog dlatch.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$dlatch
+sim -r tb_dlatch.fst -scope tb_dlatch.uut -sim-cmp dlatch
diff --git a/tests/sim/sim_dlatchsr.ys b/tests/sim/sim_dlatchsr.ys
new file mode 100644
index 000000000..c83051c8b
--- /dev/null
+++ b/tests/sim/sim_dlatchsr.ys
@@ -0,0 +1,10 @@
+read_verilog -icells <<EOT
+module dlatchsr(input d, set, clr, en, output reg q);
+$dlatchsr #(.EN_POLARITY(1'b1), .CLR_POLARITY(1'b1), .SET_POLARITY(1'b1), .WIDTH(1)) uut (.EN(en), .SET(set), .CLR(clr), .D(d), .Q(q));
+endmodule
+EOT
+proc
+opt_dff
+stat
+select -assert-count 1 t:$dlatchsr
+sim -r tb_dlatchsr.fst -scope tb_dlatchsr.uut -sim-cmp dlatchsr
diff --git a/tests/sim/sim_sdff.ys b/tests/sim/sim_sdff.ys
new file mode 100644
index 000000000..a812c5d80
--- /dev/null
+++ b/tests/sim/sim_sdff.ys
@@ -0,0 +1,6 @@
+read_verilog sdff.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$sdff
+sim -clock clk -r tb_sdff.fst -scope tb_sdff.uut -sim-cmp sdff
diff --git a/tests/sim/sim_sdffce.ys b/tests/sim/sim_sdffce.ys
new file mode 100644
index 000000000..b28acb83d
--- /dev/null
+++ b/tests/sim/sim_sdffce.ys
@@ -0,0 +1,6 @@
+read_verilog sdffce.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$sdffce
+sim -clock clk -r tb_sdffce.fst -scope tb_sdffce.uut -sim-cmp sdffce
diff --git a/tests/sim/sim_sdffe.ys b/tests/sim/sim_sdffe.ys
new file mode 100644
index 000000000..044f78eb3
--- /dev/null
+++ b/tests/sim/sim_sdffe.ys
@@ -0,0 +1,6 @@
+read_verilog sdffe.v
+proc
+opt_dff
+stat
+select -assert-count 1 t:$sdffe
+sim -clock clk -r tb_sdffe.fst -scope tb_sdffe.uut -sim-cmp sdffe
diff --git a/tests/sim/tb/tb_adff.v b/tests/sim/tb/tb_adff.v
new file mode 100755
index 000000000..f1bc3547e
--- /dev/null
+++ b/tests/sim/tb/tb_adff.v
@@ -0,0 +1,40 @@
+`timescale 1ns/1ns 
+module tb_adff();
+	reg clk = 0;
+	reg rst = 0;
+	reg d = 0;
+	wire q;
+
+	adff uut(.clk(clk),.d(d),.rst(rst),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_adff");
+		$dumpvars(0,tb_adff);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_adffe.v b/tests/sim/tb/tb_adffe.v
new file mode 100755
index 000000000..bb23f963d
--- /dev/null
+++ b/tests/sim/tb/tb_adffe.v
@@ -0,0 +1,58 @@
+`timescale 1ns/1ns 
+module tb_adffe();
+	reg clk = 0;
+	reg rst = 0;
+	reg d = 0;
+	reg en = 0;
+	wire q;
+
+	adffe uut(.clk(clk),.d(d),.rst(rst),.en(en),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_adffe");
+		$dumpvars(0,tb_adffe);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		en = 1;
+		rst = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_adlatch.v b/tests/sim/tb/tb_adlatch.v
new file mode 100755
index 000000000..59dd498d2
--- /dev/null
+++ b/tests/sim/tb/tb_adlatch.v
@@ -0,0 +1,70 @@
+`timescale 1ns/1ns 
+module tb_adlatch();
+	reg clk = 0;
+	reg rst = 0;
+	reg en = 0;
+	reg d = 0;
+	wire q;
+
+	adlatch uut(.d(d),.rst(rst),.en(en),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_adlatch");
+		$dumpvars(0,tb_adlatch);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		en = 1;
+		rst = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_aldff.v b/tests/sim/tb/tb_aldff.v
new file mode 100755
index 000000000..0591c8b3c
--- /dev/null
+++ b/tests/sim/tb/tb_aldff.v
@@ -0,0 +1,73 @@
+`timescale 1ns/1ns 
+module tb_aldff();
+	reg clk = 0;
+	reg aload = 0;
+	reg [0:3] d  = 4'b0000;
+	reg [0:3] ad = 4'b1010;
+	wire [0:3] q;
+
+	aldff uut(.clk(clk),.d(d),.ad(ad),.aload(aload),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_aldff");
+		$dumpvars(0,tb_aldff);
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		aload = 1;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		aload = 0;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		aload = 1;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		aload = 0;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_aldffe.v b/tests/sim/tb/tb_aldffe.v
new file mode 100755
index 000000000..c3cb57f4e
--- /dev/null
+++ b/tests/sim/tb/tb_aldffe.v
@@ -0,0 +1,75 @@
+`timescale 1ns/1ns 
+module tb_aldffe();
+	reg clk = 0;
+	reg aload = 0;
+	reg [0:3] d  = 4'b0000;
+	reg [0:3] ad = 4'b1010;
+	reg en = 0;
+	wire [0:3] q;
+
+	aldffe uut(.clk(clk),.d(d),.ad(ad),.aload(aload),.en(en),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_aldffe");
+		$dumpvars(0,tb_aldffe);
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		aload = 1;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		aload = 0;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		en = 1;
+		aload = 1;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		aload = 0;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		d = 4'b1100;
+		#10
+		d = 4'b0011;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_dff.v b/tests/sim/tb/tb_dff.v
new file mode 100755
index 000000000..aa41d1c6c
--- /dev/null
+++ b/tests/sim/tb/tb_dff.v
@@ -0,0 +1,47 @@
+`timescale 1ns/1ns 
+module tb_dff();
+	reg clk = 0;
+	reg d = 0;
+	wire q;
+
+	dff uut(.clk(clk),.d(d),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_dff");
+		$dumpvars(0,tb_dff);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_dffe.v b/tests/sim/tb/tb_dffe.v
new file mode 100755
index 000000000..4e262b928
--- /dev/null
+++ b/tests/sim/tb/tb_dffe.v
@@ -0,0 +1,42 @@
+`timescale 1ns/1ns 
+module tb_dffe();
+	reg clk = 0;
+	reg en = 0;
+	reg d = 0;
+	wire q;
+
+	dffe uut(.clk(clk),.d(d),.en(en),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_dffe");
+		$dumpvars(0,tb_dffe);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		en = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_dffsr.v b/tests/sim/tb/tb_dffsr.v
new file mode 100755
index 000000000..6ecb85d67
--- /dev/null
+++ b/tests/sim/tb/tb_dffsr.v
@@ -0,0 +1,69 @@
+`timescale 1ns/1ns 
+module tb_dffsr();
+	reg clk = 0;
+	reg d = 0;
+	reg set = 0;
+	reg clr = 0;
+	wire q;
+
+	dffsr uut(.d(d),.clk(clk),.set(set),.clr(clr),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_dffsr");
+		$dumpvars(0,tb_dffsr);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		clr = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		clr = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		set = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		set = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_dlatch.v b/tests/sim/tb/tb_dlatch.v
new file mode 100755
index 000000000..aea6cb0a3
--- /dev/null
+++ b/tests/sim/tb/tb_dlatch.v
@@ -0,0 +1,50 @@
+`timescale 1ns/1ns 
+module tb_dlatch();
+	reg clk = 0;
+	reg en = 0;
+	reg d = 0;
+	wire q;
+
+	dlatch uut(.d(d),.en(en),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_dlatch");
+		$dumpvars(0,tb_dlatch);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		en = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_dlatchsr.v b/tests/sim/tb/tb_dlatchsr.v
new file mode 100755
index 000000000..0105d3288
--- /dev/null
+++ b/tests/sim/tb/tb_dlatchsr.v
@@ -0,0 +1,65 @@
+`timescale 1ns/1ns 
+module tb_dlatchsr();
+	reg d = 0;
+	reg set = 0;
+	reg clr = 0;
+	wire q;
+
+	dlatchsr uut(.d(d),.set(set),.clr(clr),.q(q));
+
+	initial
+	begin
+		$dumpfile("tb_dlatchsr");
+		$dumpvars(0,tb_dlatchsr);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		clr = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		clr = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		set = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		set = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_sdff.v b/tests/sim/tb/tb_sdff.v
new file mode 100755
index 000000000..f8e2a1c9d
--- /dev/null
+++ b/tests/sim/tb/tb_sdff.v
@@ -0,0 +1,48 @@
+`timescale 1ns/1ns 
+module tb_sdff();
+	reg clk = 0;
+	reg rst = 0;
+	reg d = 0;
+	wire q;
+
+	sdff uut(.clk(clk),.d(d),.rst(rst),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_sdff");
+		$dumpvars(0,tb_sdff);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_sdffce.v b/tests/sim/tb/tb_sdffce.v
new file mode 100755
index 000000000..1c9952806
--- /dev/null
+++ b/tests/sim/tb/tb_sdffce.v
@@ -0,0 +1,79 @@
+`timescale 1ns/1ns 
+module tb_sdffce();
+	reg clk = 0;
+	reg rst = 0;
+	reg d = 0;
+	reg en = 0;
+	wire q;
+
+	sdffce uut(.clk(clk),.d(d),.rst(rst),.en(en),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_sdffce");
+		$dumpvars(0,tb_sdffce);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		en = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule
diff --git a/tests/sim/tb/tb_sdffe.v b/tests/sim/tb/tb_sdffe.v
new file mode 100755
index 000000000..36072f93d
--- /dev/null
+++ b/tests/sim/tb/tb_sdffe.v
@@ -0,0 +1,70 @@
+`timescale 1ns/1ns 
+module tb_sdffe();
+	reg clk = 0;
+	reg rst = 0;
+	reg d = 0;
+	reg en = 0;
+	wire q;
+
+	sdffe uut(.clk(clk),.d(d),.rst(rst),.en(en),.q(q));
+
+	always
+		#(5) clk <= !clk;
+
+	initial
+	begin
+		$dumpfile("tb_sdffe");
+		$dumpvars(0,tb_sdffe);
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		en = 1;
+		rst = 1;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		rst = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		d = 1;
+		#10
+		d = 0;
+		#10
+		$finish;
+	end
+endmodule