add tristate buffer and test

2 files changed, 8 insertions, 2 deletions

diff --git a/techlibs/gowin/cells_sim.v b/techlibs/gowin/cells_sim.v
index 0fe2c8c52..cc1ac48e6 100644
--- a/techlibs/gowin/cells_sim.v
+++ b/techlibs/gowin/cells_sim.v
@@ -302,6 +302,12 @@ module OBUF(output O, input I);
 	assign O = I;
 endmodule
 
+module TBUF (O, I, OEN);
+  input I, OEN;
+  output O;
+  assign O = OEN ? I : 1'bz;
+endmodule
+
 module GSR (input GSRI);
 	wire GSRO = GSRI;
 endmodule
diff --git a/techlibs/gowin/synth_gowin.cc b/techlibs/gowin/synth_gowin.cc
index e9b2ccded..d541edd84 100644
--- a/techlibs/gowin/synth_gowin.cc
+++ b/techlibs/gowin/synth_gowin.cc
@@ -174,7 +174,7 @@ struct SynthGowinPass : public ScriptPass
 			run("synth -run coarse");
 		}
 		
-                if (!nobram && check_label("bram", "(skip if -nobram)"))
+		if (!nobram && check_label("bram", "(skip if -nobram)"))
 		{
 			run("memory_bram -rules +/gowin/bram.txt");
 			run("techmap -map +/gowin/brams_map.v -map +/gowin/cells_sim.v");
@@ -230,7 +230,7 @@ struct SynthGowinPass : public ScriptPass
 			run("techmap -map +/gowin/cells_map.v");
 			run("setundef -undriven -params -zero");
 			run("hilomap -singleton -hicell VCC V -locell GND G");
-			run("iopadmap -bits -inpad IBUF O:I -outpad OBUF I:O", "(unless -noiopads)");
+			run("iopadmap -bits -inpad IBUF O:I -outpad OBUF I:O, -toutpad TBUF OEN:I:O", "(unless -noiopads)");
 			run("dffinit  -ff DFF Q INIT");
 			run("clean");