Trends, bugfix in read of DsTrend buffer

xtt/lib/xtt/src/xtt_trend.cpp

@@ -640,12 +640,8 @@ void XttTrend::trend_scan(void* data)
           idx = write_buffer * trend_buff_size / 2
               + int(trend->trend_p[i]->NextWriteIndex[write_buffer])
               - (values - 1 - k);
-          if (idx == 0 || idx == trend_buff_size / 2)
-            idx = trend->trend_p[i]->NoOfSample - 1
-                + (!write_buffer) * trend_buff_size / 2;
-          else
-            idx--;
-
+	  if (idx < 0)
+	    idx += trend_buff_size;
           trend->gcd->y_data[i][0] = trend->trend_p[i]->DataBuffer[idx];
         }
         trend->curve->points_added(&size);