* src/queue.c, src/queue.h: New files. Generic doubly linked list.

Rev: src/queue.c:1.1
Rev: src/queue.h:1.1

src/queue.c

+/* queue.c
+ *
+ * $Id$
+ *
+ * Generic doubly linked list. */
+
+/* lsh, an implementation of the ssh protocol
+ *
+ * Copyright (C) 1998 Niels Mller
+ *
+ * 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 of the
+ * License, 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
+ */
+
+#include "queue.h"
+
+#include "werror.h"
+
+#include <assert.h>
+
+/* Short cuts */
+#define next np_links[LSH_QUEUE_NEXT]
+#define prev np_links[LSH_QUEUE_PREV]
+
+#define head ht_links[LSH_QUEUE_HEAD]
+#define tail ht_links[LSH_QUEUE_TAIL]
+#define tailprev ht_links[LSH_QUEUE_TAILPREV]
+
+#define EMPTYP(q) ((q)->tailprev == (struct lsh_queue_node *) (q))
+
+#if 1
+static void sanity_check_queue(struct lsh_queue *q)
+{
+  struct lsh_queue_node *n;
+
+  debug("sanity_check_queue: q = %xi\n", (UINT32) q);
+  if (q->tail)
+    fatal("sanity_check_queue: q->tail not NULL!\n");
+
+  n = q->head;
+
+#if 0
+  if (EMPTYP(q))
+    {
+      debug("  queue is empty\n");
+      if (n->prev)
+	fatal("sanity_check_queue: "
+	      "Queue looks empty, but n->prev not NULL!\n");
+      if (q->tail != (struct lsh_queue_node *) q)
+	fatal("sanity_check_queue: "
+	      "Queue looks empty, but q->tail != q !\n");
+      return;
+    }
+#endif
+  if (n->prev != (struct lsh_queue_node *) q)
+    fatal("sanity_check_queue: head->next != &q->head !\n");
+
+  while (n->next)
+    {
+      debug("  n = %xi\n", (UINT32) n);
+      
+      if (n->prev->next != n)
+	fatal("n->prev->next != n !\n");
+
+      n = n->next;
+    }
+  if (n != (struct lsh_queue_node *) &(q->tail))
+    fatal("n != n &t->tail!\n");
+}
+#else
+#define sanity_check_queue(x)
+#endif
+
+void lsh_queue_init(struct lsh_queue *q)
+{
+  q->head = (struct lsh_queue_node *) &(q->tail);
+  q->tail = NULL;
+  q->tailprev = (struct lsh_queue_node *) &(q->head);
+  sanity_check_queue(q);
+}
+
+int lsh_queue_is_empty(struct lsh_queue *q)
+{
+  sanity_check_queue(q);
+  return EMPTYP(q);
+}
+
+void lsh_queue_add_head(struct lsh_queue *q, struct lsh_queue_node *n)
+{
+  sanity_check_queue(q);
+  n->next = q->head;
+  n->prev = (struct lsh_queue_node *) &(q->head);
+  n->prev->next = n;
+  n->next->prev = n;
+  sanity_check_queue(q);
+}
+
+void lsh_queue_add_tail(struct lsh_queue *q, struct lsh_queue_node *n)
+{
+  sanity_check_queue(q);
+  n->next = (struct lsh_queue_node *) &(q->tail);
+  n->prev = q->tailprev;
+  n->prev->next = n;
+  n->next->prev = n;
+  sanity_check_queue(q);
+}
+
+void lsh_queue_remove(struct lsh_queue_node *n)
+{
+  assert(n->next);
+  assert(n->prev);
+  n->next->prev = n->prev;
+  n->prev->next = n->next;
+}
+
+struct lsh_queue_node *lsh_queue_remove_head(struct lsh_queue *q)
+{
+  struct lsh_queue_node *n = q->head;
+
+  sanity_check_queue(q);
+  assert(!EMPTYP(q));
+  lsh_queue_remove(n);
+  sanity_check_queue(q);
+
+  return n;
+}
+
+struct lsh_queue_node *lsh_queue_remove_tail(struct lsh_queue *q)
+{
+  struct lsh_queue_node *n = q->tailprev;
+  
+  sanity_check_queue(q);
+  assert(!EMPTYP(q));
+  lsh_queue_remove(n);
+  sanity_check_queue(q);
+
+  return n;
+}
+
+  

src/queue.h

+/* queue.h
+ *
+ * $Id$
+ *
+ * Generic doubly linked list. */
+
+/* lsh, an implementation of the ssh protocol
+ *
+ * Copyright (C) 1998 Niels Mller
+ *
+ * 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 of the
+ * License, 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 LSH_QUEUE_H_INCLUDED
+#define LSH_QUEUE_H_INCLUDED
+
+#include "lsh.h"
+
+/* Layout taken from AmigaOS lists... The first node uses a prev
+ * pointer that points to the queue's HEAD. The last node uses a next
+ * pointer that points to the queue's TAIL field. The TAIL field is
+ * always NULL; TAILPREV points to the last node in the queue. */
+struct lsh_queue_node
+{
+  struct lsh_queue_node *np_links[2];
+};
+#define LSH_QUEUE_NEXT 0
+#define LSH_QUEUE_PREV 1
+
+struct lsh_queue
+{
+  struct lsh_queue_node *ht_links[3];
+};
+#define LSH_QUEUE_HEAD 0
+#define LSH_QUEUE_TAIL 1
+#define LSH_QUEUE_TAILPREV 2
+
+/* This macro must be used at the start of a block, to make the
+ * declarations legal. It is allowed to free n inside the loop. */
+
+#define FOR_QUEUE(q, type, n)					\
+  struct lsh_queue_node *n##_this, *n##_next;			\
+  type n;							\
+  for ( n##_this = (q)->ht_links[LSH_QUEUE_HEAD];		\
+	( n = (type) n##_this,					\
+	  (n##_next = n##_this->np_links[LSH_QUEUE_NEXT]));	\
+	n_this = n_next)
+
+void lsh_queue_init(struct lsh_queue *q);
+int lsh_queue_is_empty(struct lsh_queue *q);
+void lsh_queue_add_head(struct lsh_queue *q, struct lsh_queue_node *n);
+void lsh_queue_add_tail(struct lsh_queue *q, struct lsh_queue_node *n);
+void lsh_queue_remove(struct lsh_queue_node *n);
+struct lsh_queue_node *lsh_queue_remove_head(struct lsh_queue *q);
+struct lsh_queue_node *lsh_queue_remove_tail(struct lsh_queue *q);
+
+#endif /* LSH_QUEUE_H_INCLUDED */