gowin: Add support for true differential output

Signed-off-by: YRabbit <rabbit@yrabbit.cyou>

diff --git a/techlibs/gowin/cells_sim.v b/techlibs/gowin/cells_sim.v
index cc2ad3df5cd4dcdeb02b106b09412c53ecbf0547..3f5340b11bc3ff733bbd8b85f06cdebf24aafa9a 100644 (file)
--- a/techlibs/gowin/cells_sim.v
+++ b/techlibs/gowin/cells_sim.v
@@ -570,12 +570,14 @@ module OBUF(output O, input I);
        assign O = I;
 endmodule
 
+(* abc9_box *)
 module TBUF (O, I, OEN);
   input I, OEN;
   output O;
   assign O = OEN ? 1'bz : I;
 endmodule
 
+(* abc9_box *)
 module IOBUF (O, IO, I, OEN);
   input I,OEN;
   output O;
@@ -584,6 +586,15 @@ module IOBUF (O, IO, I, OEN);
   assign I = IO;
 endmodule
 
+(* abc9_box *)
+module TLVDS_OBUF (I, O, OB);
+  input I;
+  output O;
+  output OB;
+  assign O = I;
+  assign OB = ~I;
+endmodule
+
 module GSR (input GSRI);
        wire GSRO = GSRI;
 endmodule