snarfed from adns

diff --git a/layout/dlist.h b/layout/dlist.h
new file mode 100644 (file)
index 0000000..76fc74c
--- /dev/null
+++ b/layout/dlist.h
@@ -0,0 +1,54 @@
+/*
+ * dlist.h
+ * - macros for handling doubly linked lists
+ */
+/*
+ *  This file is
+ *    Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
+ *
+ *  It is part of adns, which is
+ *    Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
+ *    Copyright (C) 1999 Tony Finch <dot@dotat.at>
+ *  
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2, or (at your option)
+ *  any later version.
+ *  
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *  
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software Foundation,
+ *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
+ */
+
+#ifndef ADNS_DLIST_H_INCLUDED
+#define ADNS_DLIST_H_INCLUDED
+
+#define LIST_INIT(list) ((list).head= (list).tail= 0)
+#define LINK_INIT(link) ((link).next= (link).back= 0)
+
+#define LIST_UNLINK_PART(list,node,part)                                   \
+  do {                                                                     \
+    if ((node)->part back) (node)->part back->part next= (node)->part next; \
+      else                                  (list).head= (node)->part next; \
+    if ((node)->part next) (node)->part next->part back= (node)->part back; \
+      else                                  (list).tail= (node)->part back; \
+  } while(0)
+
+#define LIST_LINK_TAIL_PART(list,node,part)            \
+  do {                                                 \
+    (node)->part next= 0;                              \
+    (node)->part back= (list).tail;                    \
+    if ((list).tail) (list).tail->part next= (node);   \
+    else (list).head= (node);                          \
+    (list).tail= (node);                               \
+  } while(0)
+
+#define LIST_UNLINK(list,node) LIST_UNLINK_PART(list,node,)
+#define LIST_LINK_TAIL(list,node) LIST_LINK_TAIL_PART(list,node,)
+
+#endif