pack-objects: factor out name_hash

As the pack-objects system grows beyond the single
pack-objects.c file, more parts (like the soon-to-exist
bitmap code) will need to compute hashes for matching
deltas. Factor out name_hash to make it available to other
files.

Signed-off-by: Vicent Marti <tanoku@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/pack-objects.c

@@ -778,26 +778,6 @@ static void write_pack_file(void)
 			written, nr_result);
 }
 
-static uint32_t name_hash(const char *name)
-{
-	uint32_t c, hash = 0;
-
-	if (!name)
-		return 0;
-
-	/*
-	 * This effectively just creates a sortable number from the
-	 * last sixteen non-whitespace characters. Last characters
-	 * count "most", so things that end in ".c" sort together.
-	 */
-	while ((c = *name++) != 0) {
-		if (isspace(c))
-			continue;
-		hash = (hash >> 2) + (c << 24);
-	}
-	return hash;
-}
-
 static void setup_delta_attr_check(struct git_attr_check *check)
 {
 	static struct git_attr *attr_delta;
@@ -826,7 +806,7 @@ static int add_object_entry(const unsigned char *sha1, enum object_type type,
 	struct object_entry *entry;
 	struct packed_git *p, *found_pack = NULL;
 	off_t found_offset = 0;
-	uint32_t hash = name_hash(name);
+	uint32_t hash = pack_name_hash(name);
 	uint32_t index_pos;
 
 	entry = packlist_find(&to_pack, sha1, &index_pos);
@@ -1082,7 +1062,7 @@ static void add_preferred_base_object(const char *name)
 {
 	struct pbase_tree *it;
 	int cmplen;
-	unsigned hash = name_hash(name);
+	unsigned hash = pack_name_hash(name);
 
 	if (!num_preferred_base || check_pbase_path(hash))
 		return;

pack-objects.h

@@ -44,4 +44,24 @@ struct object_entry *packlist_find(struct packing_data *pdata,
 				   const unsigned char *sha1,
 				   uint32_t *index_pos);
 
+static inline uint32_t pack_name_hash(const char *name)
+{
+	uint32_t c, hash = 0;
+
+	if (!name)
+		return 0;
+
+	/*
+	 * This effectively just creates a sortable number from the
+	 * last sixteen non-whitespace characters. Last characters
+	 * count "most", so things that end in ".c" sort together.
+	 */
+	while ((c = *name++) != 0) {
+		if (isspace(c))
+			continue;
+		hash = (hash >> 2) + (c << 24);
+	}
+	return hash;
+}
+
 #endif