Oscillator of ATR

//+------------------------------------------------------------------+
//|                                            Oscillator of ATR.mq4 |
//|                                                   vasbsm@mail.ru |
//|                                                                  |
//+------------------------------------------------------------------+
#property copyright "vasbsm@mail.ru"
#property link      ""

#property indicator_separate_window
#property indicator_buffers 1
#property indicator_color1 DodgerBlue
#property indicator_width1 3
//---- input parameters
extern int       FirstAtrPeriod=138;
extern int       SecondAtrPeriod=94;
extern int       TypeMA=0;
//-----------------------
double OscAtrBuffer[];
double TempBuffer[];
//------------------------
int init()
  {
   string short_name;
   IndicatorBuffers(2);
   SetIndexStyle(0,DRAW_HISTOGRAM);
   SetIndexBuffer(0,OscAtrBuffer);
   SetIndexBuffer(1,TempBuffer);
   short_name="Oscillator of ATR("+FirstAtrPeriod+","+SecondAtrPeriod+","+"Type of MA="+TypeMA+")";
   IndicatorShortName(short_name);
   SetIndexLabel(0,short_name);
   SetIndexDrawBegin(0,FirstAtrPeriod);
   return(0);
  }
//---------------------------------------------
int start()
  {
   int    counted_bars=IndicatorCounted(),i;
   if(Bars<=FirstAtrPeriod) return(0);
   if(counted_bars<1)
      for(i=1;i<=FirstAtrPeriod;i++) OscAtrBuffer[Bars-i]=0.0;    
   //----------------
      i=Bars-counted_bars-1;
   while(i>=0)
     {
      double high=High[i];
      double low =Low[i];
      if(i==Bars-1) TempBuffer[i]=high-low;
      else
        {
         double prevclose=Close[i+1];
         TempBuffer[i]=1000*(MathMax(high,prevclose)-MathMin(low,prevclose));
        }
      i--;
     }
    //---------------
   if(counted_bars>0) counted_bars--;
   int limit=Bars-counted_bars;
   for(i=0; i<limit; i++)
      OscAtrBuffer[i]=iMAOnArray(TempBuffer,Bars,FirstAtrPeriod,0,TypeMA,i)-iMAOnArray(TempBuffer,Bars,SecondAtrPeriod,0,TypeMA,i);
    //---------------   
   return(0);
  }
//+------------------------------------------------------------------+