From: Keith Packard <keithp@keithp.com>
Date: Fri, 6 Jun 2014 01:31:06 +0000 (-0700)
Subject: altos: ao_distance was overflowing when checking for longitude wrap
X-Git-Tag: 1.3.2.2~14
X-Git-Url: https://git.gag.com/?a=commitdiff_plain;h=d7df6e8c47df35c0d27f1a2559ecc305ef28d271;p=fw%2Faltos

altos: ao_distance was overflowing when checking for longitude wrap

Need to shift everyone right one bit to fit in 32 bits

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

diff --git a/src/kernel/ao_distance.c b/src/kernel/ao_distance.c
index ba7d59fe..5654182a 100644
--- a/src/kernel/ao_distance.c
+++ b/src/kernel/ao_distance.c
@@ -24,6 +24,7 @@ ao_dist(int32_t a, int32_t b)
 	int32_t	d = a - b;
 	if (d < 0)
 		d = -d;
+
 	return (uint32_t) ((int64_t) d * 111198 / 10000000);
 }
 
@@ -98,7 +99,7 @@ ao_lon_dist(int32_t lon_a, int32_t lon_b)
 	uint32_t	lon_dist;
 
 	/* check if it's shorter to go the other way around */
-	if (lon_a < lon_b - 1800000000)
+	if ((lon_a >> 1) < (lon_b >> 1) - (1800000000 >> 1))
 		lon_a += 3600000000;
 	lon_dist = ao_dist(lon_a, lon_b);
 	if (c) {