1 files changed, 23 insertions, 0 deletions
diff --git a/link.h b/link.h
new file mode 100644
index 0000000..09f358f
--- /dev/null
+++ b/link.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include <stdlib.h>
+
+#define OFFSET(type, attr) ((size_t) &((type *)0)->attr)
+#define UPCAST(ptr, type) ({ \
+	const typeof( ((type *)0)->link ) *__mptr = (ptr); \
+	(type *)( (char *)__mptr - OFFSET(type, link) ); })
+
+#define LIST_HEAD ((struct link) { .prev = NULL, .next = NULL })
+
+struct link {
+	struct link *prev, *next;
+};
+
+int list_len(struct link *list);
+struct link* list_back(struct link *list);
+
+void link_push_back(struct link *list, struct link *link);
+
+void link_prepend(struct link *list, struct link *link);
+void link_append(struct link *list, struct link *link);
+void link_pop(struct link *link);