pack-bitmap: introduce bitmap_walk_contains()

We will use this helper function in a following commit to
tell us if an object is packed.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pack-bitmap.c

@@ -832,6 +832,18 @@ int reuse_partial_packfile_from_bitmap(struct bitmap_index *bitmap_git,
 	return 0;
 }
 
+int bitmap_walk_contains(struct bitmap_index *bitmap_git,
+			 struct bitmap *bitmap, const struct object_id *oid)
+{
+	int idx;
+
+	if (!bitmap)
+		return 0;
+
+	idx = bitmap_position(bitmap_git, oid);
+	return idx >= 0 && bitmap_get(bitmap, idx);
+}
+
 void traverse_bitmap_commit_list(struct bitmap_index *bitmap_git,
 				 show_reachable_fn show_reachable)
 {

pack-bitmap.h

@@ -3,6 +3,7 @@
 
 #include "ewah/ewok.h"
 #include "khash.h"
+#include "pack.h"
 #include "pack-objects.h"
 
 struct commit;
@@ -53,6 +54,8 @@ int reuse_partial_packfile_from_bitmap(struct bitmap_index *,
 int rebuild_existing_bitmaps(struct bitmap_index *, struct packing_data *mapping,
 			     kh_oid_map_t *reused_bitmaps, int show_progress);
 void free_bitmap_index(struct bitmap_index *);
+int bitmap_walk_contains(struct bitmap_index *,
+			 struct bitmap *bitmap, const struct object_id *oid);
 
 /*
  * After a traversal has been performed by prepare_bitmap_walk(), this can be