anchor.diff:  
         Bit #(64) res = ( pack (v) );
         let fcsr = exception_to_fcsr(e);
  -      fa_driveResponse (res, fcsr);
         resultR     <= tagged Valid (tuple2 (res, fcsr));
         stateR      <= FBOX_RSP;
      endrule
  
positive.code:                         , sfd:  dV1.sfd};
        Bit #(64) res = pack (r1);
  
        fa_driveResponse (res, 0);
        resultR     <= tagged Valid (tuple2 (res, 0));
        stateR      <= FBOX_RSP;
     endrule
  
negative.code:       match {.f, .e} = Tuple2#(FSingle, FloatingPoint::Exception)'(vFixedToFloat( v, 6'd0, rmd));
        Bit #(64) res = fv_nanbox (extend (pack ( f )));
        let fcsr = exception_to_fcsr(e);
        resultR     <= tagged Valid (tuple2 (res, fcsr));
        stateR      <= FBOX_RSP;
     endrule
  