flight/pios/common/libraries/yaffs2/inc/yaffs_list.h

   1 /*
   2  * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
   3  *
   4  * Copyright (C) 2002-2011 Aleph One Ltd.
   5  *   for Toby Churchill Ltd and Brightstar Engineering
   6  *
   7  * Created by Charles Manning <charles@aleph1.co.uk>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU Lesser General Public License version 2.1 as
  11  * published by the Free Software Foundation.
  12  *
  13  * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
  14  */
  15
  16 /*
  17  * This file is just holds extra declarations of macros that would normally
  18  * be providesd in the Linux kernel. These macros have been written from
  19  * scratch but are functionally equivalent to the Linux ones.
  20  *
  21  */
  22
  23 #ifndef __YAFFS_LIST_H__
  24 #define __YAFFS_LIST_H__
  25
  26
  27 /*
  28  * This is a simple doubly linked list implementation that matches the
  29  * way the Linux kernel doubly linked list implementation works.
  30  */
  31
  32 struct list_head {
  33         struct list_head *next; /* next in chain */
  34         struct list_head *prev; /* previous in chain */
  35 };
  36
  37
  38 /* Initialise a static list */
  39 #define LIST_HEAD(name) \
  40 struct list_head name = { &(name), &(name)}
  41
  42
  43
  44 /* Initialise a list head to an empty list */
  45 #define INIT_LIST_HEAD(p) \
  46 do { \
  47         (p)->next = (p);\
  48         (p)->prev = (p); \
  49 } while (0)
  50
  51
  52 /* Add an element to a list */
  53 static inline void list_add(struct list_head *new_entry,
  54                                 struct list_head *list)
  55 {
  56         struct list_head *list_next = list->next;
  57
  58         list->next = new_entry;
  59         new_entry->prev = list;
  60         new_entry->next = list_next;
  61         list_next->prev = new_entry;
  62
  63 }
  64
  65 static inline void list_add_tail(struct list_head *new_entry,
  66                                  struct list_head *list)
  67 {
  68         struct list_head *list_prev = list->prev;
  69
  70         list->prev = new_entry;
  71         new_entry->next = list;
  72         new_entry->prev = list_prev;
  73         list_prev->next = new_entry;
  74
  75 }
  76
  77
  78 /* Take an element out of its current list, with or without
  79  * reinitialising the links.of the entry*/
  80 static inline void list_del(struct list_head *entry)
  81 {
  82         struct list_head *list_next = entry->next;
  83         struct list_head *list_prev = entry->prev;
  84
  85         list_next->prev = list_prev;
  86         list_prev->next = list_next;
  87
  88 }
  89
  90 static inline void list_del_init(struct list_head *entry)
  91 {
  92         list_del(entry);
  93         entry->next = entry->prev = entry;
  94 }
  95
  96
  97 /* Test if the list is empty */
  98 static inline int list_empty(struct list_head *entry)
  99 {
 100         return (entry->next == entry);
 101 }
 102
 103
 104 /* list_entry takes a pointer to a list entry and offsets it to that
 105  * we can find a pointer to the object it is embedded in.
 106  */
 107
 108
 109 #define list_entry(entry, type, member) \
 110         ((type *)((char *)(entry)-(unsigned long)(&((type *)NULL)->member)))
 111
 112
 113 /* list_for_each and list_for_each_safe  iterate over lists.
 114  * list_for_each_safe uses temporary storage to make the list delete safe
 115  */
 116
 117 #define list_for_each(itervar, list) \
 118         for (itervar = (list)->next; itervar != (list); itervar = itervar->next)
 119
 120 #define list_for_each_safe(itervar, save_var, list) \
 121         for (itervar = (list)->next, save_var = (list)->next->next; \
 122                 itervar != (list); \
 123                 itervar = save_var, save_var = save_var->next)
 124
 125
 126 #endif