STEP_C1          1166 ext/gd/libgd/gd_topal.c       inc1 = inc1 * (2 * STEP_C1) + STEP_C1 * STEP_C1;
STEP_C1          1193 ext/gd/libgd/gd_topal.c 	      xx1 += 2 * STEP_C1 * STEP_C1;