+ SETUP(y1, primary_light, sf->primary, y1sz);
+ if (y2sz) {
+ SETUP(y2, sf->primary, sf->secondary, y2sz);
+ NEXT(y2); /* skip the first one, its the same as the last of y1 */
+ }
+ SETUP(y3, sf->secondary, secondary_light, y3sz);
+
+ for (y1 = y1sz; y1 > 0; --y1) {