1 files changed, 51 insertions, 0 deletions
diff --git a/libiberty/insque.c b/libiberty/insque.c
new file mode 100644
index 000000000..fd02357bb
--- /dev/null
+++ b/libiberty/insque.c
@@ -0,0 +1,51 @@
+/* insque(3C) routines
+   This file is in the public domain.  */
+
+/*
+
+@deftypefn Supplemental void insque (struct qelem *@var{elem}, @
+  struct qelem *@var{pred})
+@deftypefnx Supplemental void remque (struct qelem *@var{elem})
+
+Routines to manipulate queues built from doubly linked lists.  The
+@code{insque} routine inserts @var{elem} in the queue immediately
+after @var{pred}.  The @code{remque} routine removes @var{elem} from
+its containing queue.  These routines expect to be passed pointers to
+structures which have as their first members a forward pointer and a
+back pointer, like this prototype (although no prototype is provided):
+
+@example
+struct qelem @{
+  struct qelem *q_forw;
+  struct qelem *q_back;
+  char q_data[];
+@};
+@end example
+
+@end deftypefn
+
+*/
+
+
+struct qelem {
+  struct qelem *q_forw;
+  struct qelem *q_back;
+};
+
+
+void
+insque (struct qelem *elem, struct qelem *pred)
+{
+  elem -> q_forw = pred -> q_forw;
+  pred -> q_forw -> q_back = elem;
+  elem -> q_back = pred;
+  pred -> q_forw = elem;
+}
+
+
+void
+remque (struct qelem *elem)
+{
+  elem -> q_forw -> q_back = elem -> q_back;
+  elem -> q_back -> q_forw = elem -> q_forw;
+}