anchor.diff:        ystep <= cfg.ystep;
         xlimit <= cfg.xlimit;
         ylimit <= cfg.ylimit;
  -   endmethod
  +      isFirstReg <= True;
  +      isLastReg <= (cfg.xbase+cfg.xstep) > cfg.xlimit && (cfg.ybase+cfg.ystep) > cfg.ylimit;
  +   endmethod
  +   method Bool isFirst(); return isFirstReg; endmethod
  +   method Bool isLast(); return isLastReg; endmethod
      method Action display();
         $display("XYRangePipe x=%d xlimit=%d y=%d ylimit=%d xstep=%d ystep=%d", x, xlimit, xstep, y, ylimit, ystep);
      endmethod
  
positive.code: 	 end
  	 x <= newx;
  	 y <= newy;
        endmethod
        method Bool notEmpty();
  	 return guard;
  
negative.code: 
  interface XYRangePipeIfc#(type a);
     interface PipeOut#(Tuple2#(a,a)) pipe;
     method Bool isFirst();
     method Bool isLast();
     method Action start(XYRangeConfig#(a) cfg);
     method Action display();
  endinterface
  