2 files changed, 14 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index f4bb047..4d391b1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,5 @@
 *.log
 *.svg
 *.dep
+*.vvp
+*.lxt2
diff --git a/Makefile b/Makefile
index 9e8bcca..e7fc552 100644
--- a/Makefile
+++ b/Makefile
@@ -48,7 +48,10 @@ flash: $(PROGRAM).fs
 	openFPGALoader -b tangnano9k  $(FLASH_OPTS) $(PROGRAM).fs
 
 clean:
-	rm -rf *.json *.fs *.svg *.log *.dep
+	rm -rf *.json *.fs *.svg *.log *.dep *.vvp *.lxt2
+
+simu: $(PROGRAM).lxt2
+	gtkwave $<
 
 ## Patterns
 
@@ -80,6 +83,14 @@ clean:
 %.fs: %.pnr.json
 	gowin_pack -d $(DEVICE_FAMILY) -o $@ $<
 
+### simulation
+
+%.lxt2: %.vvp
+	./$< -lxt2
+
+%.vvp: %.v %.tb.v
+	iverilog -o $*.vvp $*.v $*.tb.v
+
 ## inter-file dependencies
 -include $(DEPS)
 -include $($(wildcard *.fs:.fs=.dep)