Add common linked list functions

Forms implemented to a greater or lesser degree at the moment:
ll_*   = singly-linked list
lld_*  = doubly-linked list
lldc_* = doubly-linked circular list

Change-Id: Ieed5af50fc59165c8b14c3513b3b5d0e6f7de9fa

1 files changed, 114 insertions, 0 deletions

diff --git a/firmware/include/linked_list.h b/firmware/include/linked_list.h
new file mode 100644
index 0000000..c678cfa
--- /dev/null
+++ b/firmware/include/linked_list.h
@@ -0,0 +1,114 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2014 by Michael Sevakis
+ *
+ * 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 software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#ifndef LINKED_LIST_H
+#define LINKED_LIST_H
+
+/***
+ ** NOTES:
+ ** Node field order chosen so that one type can alias the other for forward
+ ** list traveral by the same code.
+ **
+ ** Structures are separate, even if logically equivalent, to perform compile-
+ ** time type checking.
+ **
+ */
+
+
+/* (L)inked (L)ist
+ *
+ * Format:
+ *
+ *       XX->YY->ZZ->0
+ * head--^       ^
+ * tail----------+
+ */
+struct ll_head
+{
+    struct ll_node *head; /* First list item */
+    struct ll_node *tail; /* Last list item (to make insert_last O(1)) */
+};
+
+struct ll_node
+{
+    struct ll_node *next; /* Next list item */
+};
+
+void ll_init(struct ll_head *list);
+void ll_insert_next(struct ll_head *list, struct ll_node *node,
+                    struct ll_node *newnode);
+void ll_insert_last(struct ll_head *list, struct ll_node *node);
+void ll_remove_next(struct ll_head *list, struct ll_node *node);
+void ll_remove(struct ll_head *list, struct ll_node *node);
+void ll_insert_first(struct ll_head *list, struct ll_node *node);
+void ll_remove_first(struct ll_head *list);
+
+
+/* (L)inked (L)ist (D)double
+ *
+ * Format:
+ *
+ *      0<-XX<->YY<->ZZ->0
+ * head----^         ^
+ * tail--------------+
+ */
+struct lld_head
+{
+    struct lld_node *head; /* First list item */
+    struct lld_node *tail; /* Last list item (to make insert_last O(1)) */
+};
+
+struct lld_node
+{
+    struct lld_node *next; /* Next list item */
+    struct lld_node *prev; /* Previous list item */
+};
+
+void lld_init(struct lld_head *list);
+void lld_insert_first(struct lld_head *list, struct lld_node *node);
+void lld_insert_last(struct lld_head *list, struct lld_node *node);
+void lld_remove(struct lld_head *list, struct lld_node *node);
+
+
+/* (L)inked (L)ist (D)ouble (C)ircular
+ *
+ * Format:
+ *        +----------------+
+ *        |                |
+ *        +->XX<->YY<->ZZ<-+
+ * head------^
+ */
+struct lldc_head
+{
+    struct lldc_node *head; /* First list item */
+};
+
+struct lldc_node
+{
+    struct lldc_node *next; /* Next list item */
+    struct lldc_node *prev; /* Previous list item */
+};
+
+void lldc_init(struct lldc_head *list);
+void lldc_insert_first(struct lldc_head *list, struct lldc_node *node);
+void lldc_insert_last(struct lldc_head *list, struct lldc_node *node);
+void lldc_remove(struct lldc_head *list, struct lldc_node *node);
+
+#endif /* LINKED_LIST_H */