Add timescale and generated-by header to yosys-smtbmc MkVcd

Signed-off-by: Clifford Wolf <clifford@clifford.at>

diff --git a/backends/smt2/smtio.py b/backends/smt2/smtio.py
index ab20a4af2ce28a70aaa916e05114ed43447b8e55..cea0fc56c67d78abf6e0554bd3f594c459b5db9a 100644 (file)
--- a/backends/smt2/smtio.py
+++ b/backends/smt2/smtio.py
@@ -1023,6 +1023,8 @@ class MkVcd:
         assert t >= self.t
         if t != self.t:
             if self.t == -1:
+                print("$version Generated by Yosys-SMTBMC $end", file=self.f)
+                print("$timescale 1ns $end", file=self.f)
                 print("$var integer 32 t smt_step $end", file=self.f)
                 print("$var event 1 ! smt_clock $end", file=self.f)