anchor.diff:                 wfifo.deq;
                  return d;
              endmethod
  +           method Bit#(1) writeWid();
  +               return writeIdReg;
  +           endmethod
              method Bit#(busWidthBytes) writeDataByteEnable();
                  return maxBound;
              endmethod
  
positive.code:        method ActionValue#(Bit#(busWidth)) writeData();
             return 0;
         endmethod
         method Bit#(busWidthBytes) writeDataByteEnable();
             return maxBound;
         endmethod
  
negative.code:     endrule
      rule writeData;
          let data <- axiw.writeData;
          let id = axiw.writeWid;
          let byteEnable = axiw.writeDataByteEnable;
          let last = axiw.writeLastDataBeat;
          axiSlave.write.writeData(data, byteEnable, last);
  