/**********************************************************************/
/*          SUB_FUN ATAN(B/C)  MAIN VALUE AREA IS [-PI/2,PI/2]        */
/**********************************************************************/

int arctan(long B, long C)
{
	int x;
 	int absx;
 	short y;

	x=(B<<11)/C ;
	absx=_abs(x); 
	if (absx<2048)
	    y=atan_table[absx];
	else if (absx==2048)
    	y=4096;
	else
	{
    	absx=2048*2048/absx;
    	y=atan_table[absx];
    	y=8192-y;
	}
	if (x<0)
		y=-y;
	return y;
}


/**********************************************************************/
/*          SUB_FUN ATAN2(B,C)  MAIN VALUE AREA IS [-PI,PI]           */
/**********************************************************************/

int arctan2(long B, long C)
{
	int x;
 	short y;

	x=_abs((B<<11)/C) ; 
	if (x<2048)
	    y=atan_table[x];
	else if (x==2048)
	    y=4096;
	else
	{
	    x=2048*2048/x;
	    y=atan_table[x];
	    y=8192-y;
	}
	if (B<0&&C>0)
	{
	    y=-1*y;
	}
	else if (B>=0&&C<0)
	    y=16384-y;
	
	else if (B < 0 && C < 0) 
	    y=y-16384;
	return y;
}
/**********************************************************************/
/*          SUB_FUN CMD_ANALYZE()  ANALYZE THE CMD FROM PC            */
/**********************************************************************/
void noise_estim()
{
    if (num_cal<=0x100)//256 points
	   {
         noise=DATA;
         sum_n+=noise;
        }
      if (num_cal>0x100 && num_cal<0x200)//256 points
	    {
        noise=MyData[num_cal]-mean_n;
        sum_nn+=(noise*noise);
	    }
        //num_cal++;
   
	  if (num_cal==0x100) 
		{
	     mean_n=sum_n>>8;
		}
	   if (num_cal==0x200)
		{		        
	      var_n=sum_nn>>8;
	      noise_g=var_n;
	      THRESH=var_n*25;
	      flag_over=1;
	      //MIN_THRESH=360000;          
	      //MAX_THRESH=360000;
		 
		 }
}