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+/* insque(3C) routines
+ This file is in the public domain. */
+
+/*
+NAME
+ insque, remque -- insert, remove an element from a queue
+
+SYNOPSIS
+ struct qelem {
+ struct qelem *q_forw;
+ struct qelem *q_back;
+ char q_data[];
+ };
+
+ void insque (struct qelem *elem, struct qelem *pred)
+
+ void remque (struct qelem *elem)
+
+DESCRIPTION
+ Routines to manipulate queues built from doubly linked lists.
+ The insque routine inserts ELEM in the queue immediately after
+ PRED. The remque routine removes ELEM from its containing queue.
+*/
+
+
+struct qelem {
+ struct qelem *q_forw;
+ struct qelem *q_back;
+};
+
+
+void
+insque (elem, pred)
+ 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 (elem)
+ struct qelem *elem;
+{
+ elem -> q_forw -> q_back = elem -> q_back;
+ elem -> q_back -> q_forw = elem -> q_forw;
+}