From 8bd1d13b18ef4124cf7ecf232f7c03789bc10da5 Mon Sep 17 00:00:00 2001
From: robertlipe <robertlipe@gmail.com>
Date: Wed, 22 Aug 2012 03:02:12 +0000
Subject: [PATCH] Tweak EXIF reader to allow reads below sea level.

---
 gpsbabel/exif.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/gpsbabel/exif.c b/gpsbabel/exif.c
index 2876d4c4d..ae9640563 100644
--- a/gpsbabel/exif.c
+++ b/gpsbabel/exif.c
@@ -779,10 +779,21 @@ exif_waypt_from_exif_app(exif_app_t* app)
   }
 
   if (alt != unknown_alt) {
-    if (alt_ref != 0) {
+    double sign;
+    switch (alt_ref != 0) {
+    case 0:
+      sign = 1.0;
+      break;
+
+    case 1:
+      sign = -1.0;
+      break;
+
+    default:
       warning(MYNAME ": Invalid GPSAltitudeRef (%d)! Using 0 (= Sea level).\n", alt_ref);
+      sign = 1.0;
     }
-    wpt->altitude = alt;
+    wpt->altitude = sign * alt;
 #ifdef EXIF_DBG
     printf(MYNAME "-GPSAltitude =  %12.7f m\n", wpt->altitude);
 #endif
-- 
2.30.2