diff --git a/blob.h b/blob.h
new file mode 100644
index 0000000000..5cbf6d65ee
--- /dev/null
+++ b/blob.h
@@ -0,0 +1,14 @@
+#ifndef BLOB_H
+#define BLOB_H
+
+#include "object.h"
+
+extern const char *blob_type;
+
+struct blob {
+	struct object object;
+};
+
+struct blob *lookup_blob(unsigned char *sha1);
+
+#endif /* BLOB_H */
diff --git a/commit.h b/commit.h
new file mode 100644
index 0000000000..4afd27b109
--- /dev/null
+++ b/commit.h
@@ -0,0 +1,27 @@
+#ifndef COMMIT_H
+#define COMMIT_H
+
+#include "object.h"
+#include "tree.h"
+
+struct commit_list {
+	struct commit *item;
+	struct commit_list *next;
+};
+
+struct commit {
+	struct object object;
+	unsigned long date;
+	struct commit_list *parents;
+	struct tree *tree;
+};
+
+extern const char *commit_type;
+
+struct commit *lookup_commit(unsigned char *sha1);
+
+int parse_commit(struct commit *item);
+
+void free_commit_list(struct commit_list *list);
+
+#endif /* COMMIT_H */
diff --git a/object.h b/object.h
new file mode 100644
index 0000000000..bc607fd55f
--- /dev/null
+++ b/object.h
@@ -0,0 +1,29 @@
+#ifndef OBJECT_H
+#define OBJECT_H
+
+struct object_list {
+	struct object *item;
+	struct object_list *next;
+};
+
+struct object {
+	unsigned parsed : 1;
+	unsigned used : 1;
+	unsigned int flags;
+	unsigned char sha1[20];
+	const char *type;
+	struct object_list *refs;
+};
+
+int nr_objs;
+struct object **objs;
+
+struct object *lookup_object(unsigned char *sha1);
+
+void created_object(unsigned char *sha1, struct object *obj);
+
+void add_ref(struct object *refer, struct object *target);
+
+void mark_reachable(struct object *obj, unsigned int mask);
+
+#endif /* OBJECT_H */
diff --git a/tree.h b/tree.h
new file mode 100644
index 0000000000..4d5496de30
--- /dev/null
+++ b/tree.h
@@ -0,0 +1,17 @@
+#ifndef TREE_H
+#define TREE_H
+
+#include "object.h"
+
+extern const char *tree_type;
+
+struct tree {
+	struct object object;
+	unsigned has_full_path : 1;
+};
+
+struct tree *lookup_tree(unsigned char *sha1);
+
+int parse_tree(struct tree *tree);
+
+#endif /* TREE_H */