altos: Add ao_distance.c to compute cartesian distances on the globe

This is not a great circle distance, but should be good enough for
points reasonably close together

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/src/kernel/ao_distance.h b/src/kernel/ao_distance.h
new file mode 100644
index 00000000..6762434e
--- /dev/null
+++ b/src/kernel/ao_distance.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright © 2014 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * 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.
+ */
+
+#ifndef _AO_DISTANCE_H_
+#define _AO_DISTANCE_H_
+#include <stdint.h>
+
+uint32_t
+ao_distance(int32_t lat_a, int32_t lon_a, int32_t lat_b, int32_t lon_b);
+
+#endif /* _AO_DISTANCE_H_ */