1 files changed, 33 insertions, 1 deletions
diff --git a/techlibs/xilinx/cells_sim.v b/techlibs/xilinx/cells_sim.v
index 5faddcd52..1be43f9d4 100644
--- a/techlibs/xilinx/cells_sim.v
+++ b/techlibs/xilinx/cells_sim.v
@@ -59,6 +59,34 @@ module OBUF(
   assign O = I;
 endmodule
 
+module IOBUF (
+    (* iopad_external_pin *)
+    inout IO,
+    output O,
+    input I,
+    input T
+);
+    parameter integer DRIVE = 12;
+    parameter IBUF_LOW_PWR = "TRUE";
+    parameter IOSTANDARD = "DEFAULT";
+    parameter SLEW = "SLOW";
+    assign IO = T ? 1'bz : I;
+    assign O = IO;
+endmodule
+
+module OBUFT (
+    (* iopad_external_pin *)
+    output O,
+    input I,
+    input T
+);
+    parameter CAPACITANCE = "DONT_CARE";
+    parameter integer DRIVE = 12;
+    parameter IOSTANDARD = "DEFAULT";
+    parameter SLEW = "SLOW";
+    assign O = T ? 1'bz : I;
+endmodule
+
 module BUFG(
     (* clkbuf_driver *)
     output O,
@@ -126,7 +154,11 @@ endmodule
 //   assign O = IO, IO = T ? 1'bz : I;
 // endmodule
 
-module INV(output O, input I);
+module INV(
+    (* clkbuf_inv = "I" *)
+    output O,
+    input I
+);
   assign O = !I;
 endmodule