From f7813a5324be39d13ab536c245d15dfc602a7849 Mon Sep 17 00:00:00 2001
From: Tim Redfern <tim@eclectronics.org>
Date: Sun, 29 Dec 2013 12:19:38 +0000
Subject: basic type mechanism working

---
 ffmpeg/version.sh | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

(limited to 'ffmpeg/version.sh')

diff --git a/ffmpeg/version.sh b/ffmpeg/version.sh
index 8d084c2..92edcb9 100755
--- a/ffmpeg/version.sh
+++ b/ffmpeg/version.sh
@@ -1,5 +1,7 @@
 #!/bin/sh
 
+# Usage: version.sh <ffmpeg-root-dir> <output-version.h> <extra-version>
+
 # check for git short hash
 if ! test "$revision"; then
     revision=$(cd "$1" && git describe --tags --match N 2> /dev/null)
@@ -40,9 +42,17 @@ if [ -z "$2" ]; then
 fi
 
 NEW_REVISION="#define FFMPEG_VERSION \"$version\""
-OLD_REVISION=$(cat version.h 2> /dev/null)
+OLD_REVISION=$(cat "$2" 2> /dev/null | head -3 | tail -1)
+
+# String used for preprocessor guard
+GUARD=$(echo "$2" | sed 's/\//_/' | sed 's/\./_/' | tr '[:lower:]' '[:upper:]' | sed 's/LIB//')
 
-# Update version.h only on revision changes to avoid spurious rebuilds
+# Update version header only on revision changes to avoid spurious rebuilds
 if test "$NEW_REVISION" != "$OLD_REVISION"; then
-    echo "$NEW_REVISION" > "$2"
+    cat << EOF > "$2"
+#ifndef $GUARD
+#define $GUARD
+$NEW_REVISION
+#endif /* $GUARD */
+EOF
 fi
-- 
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