+ * Sample usage:
+ *
+ * \code
+ * bm = chart_init(0, ymax, N_POINTS_CURVE, ymin);
+ *
+ * chart_drawCurve(bm, curve_y, curve_points + 1);
+ * gfx_setViewRect(bm, xmin, ymax, xmax, ymin);
+ * chart_drawDots(bm, samples_x, samples_y, samples_cnt);
+ *
+ * print_bitmap(bm);
+ * \endcode
+ * \author Bernie Innocenti <bernie@codewiz.org>