1 files changed, 55 insertions, 0 deletions
diff --git a/util/alevt/dllist.h b/util/alevt/dllist.h
new file mode 100644
index 0000000..f925506
--- /dev/null
+++ b/util/alevt/dllist.h
@@ -0,0 +1,55 @@
+#ifndef DLLIST_H
+#define DLLIST_H
+
+
+struct dl_node
+{
+    struct dl_node *next;
+    struct dl_node *prev;
+};
+
+
+struct dl_head
+{
+    struct dl_node *first;
+    struct dl_node *null;
+    struct dl_node *last;
+};
+
+
+static inline struct dl_head * dl_init(struct dl_head *h)
+{
+    h->first = (struct dl_node *)&h->null;
+    h->null = 0;
+    h->last = (struct dl_node *)&h->first;
+    return h;
+}
+
+
+static inline struct dl_node * dl_remove(struct dl_node *n)
+{
+    n->prev->next = n->next;
+    n->next->prev = n->prev;
+    return n;
+}
+
+
+static inline struct dl_node *
+    dl_insert_after(struct dl_node *p, struct dl_node *n)
+{
+    n->next = p->next;
+    n->prev = p;
+    p->next = n;
+    n->next->prev = n;
+    return n;
+}
+
+#define dl_empty(h)             ((h)->first->next == 0)
+#define dl_insert_before(p, n)  dl_insert_after((p)->prev, (n))
+#define dl_insert_first(h, n)   ({ struct dl_node *_n = (n); \
+					dl_insert_before((h)->first, _n); })
+#define dl_insert_last(h, n)    ({ struct dl_node *_n = (n); \
+					dl_insert_after((h)->last, _n); })
+#define dl_remove_first(h)      dl_remove((h)->first) // mustn't be empty!
+#define dl_remove_last(h)       dl_remove((h)->last) // mustn't be empty!
+#endif