--- /dev/null
+/*
+ * Copyright Droids Corporation (2009)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Revision : $Id: f16.h,v 1.6.4.3 2008-05-10 15:06:26 zer0 Exp $
+ *
+ */
+
+#ifndef _CIRCLES_H_
+#define _CIRCLES_H_
+
+typedef struct _circle {
+ double x;
+ double y;
+ double r;
+} circle_t;
+
+/* return true if a point is in the disc */
+uint8_t pt_is_inside_circle(const point_t *p, circle_t *c);
+
+/*
+ * return values:
+ * 0 dont cross
+ * 1 one intersection point
+ * 2 two intersection points
+ *
+ * p1, p2 arguments are the crossing points coordinates. Both p1 and
+ * p2 are dummy for 0 result. When result is 1, p1 and p2 are set to
+ * the same value.
+ */
+uint8_t circle_intersect(const circle_t *c1, const circle_t *c2,
+ point_t *p1, point_t *p2);
+
+#endif /* _CIRCLES_H_ */