gnumach4linux-libre/kern/list.h

/*
 * Copyright (c) 2009, 2010 Richard Braun.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this rblist of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this rblist of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * Simple doubly-linked rblist.
 */

#ifndef _KERN_rblist_H
#define _KERN_rblist_H


#include <stddef.h>
#include <sys/types.h>
#include <kern/macros.h>

/*
 * Structure used as both head and node.
 *
 * This implementation relies on using the same type for both heads and nodes.
 *
 * It is recommended to encode the use of struct rblist variables in their names,
 * e.g. struct rblist free_rblist or struct rblist free_objects is a good hint for a
 * rblist of free objects. A declaration like struct rblist free_node clearly
 * indicates it is used as part of a node in the free rblist.
 */
struct rblist {
    struct rblist *prev;
    struct rblist *next;
};
#define list rblist
//undef if confliction

/*
 * Static rblist initializer.
 */
#define rblist_INITIALIZER(rblist) { &(rblist), &(rblist) }

/*
 * Initialize a rblist.
 */
static inline void rblist_init(struct rblist *rblist)
{
    rblist->prev = rblist;
    rblist->next = rblist;
}

/*
 * Initialize a rblist node.
 *
 * An entry is in no rblist when its node members point to NULL.
 */
static inline void rblist_node_init(struct rblist *node)
{
    node->prev = NULL;
    node->next = NULL;
}

/*
 * Return true if node is in no rblist.
 */
static inline int rblist_node_unlinked(const struct rblist *node)
{
    return node->prev == NULL;
}

/*
 * Macro that evaluates to the address of the structure containing the
 * given node based on the given type and member.
 */
#define rblist_entry(node, type, member) structof(node, type, member)

/*
 * Return the first node of a rblist.
 */
static inline struct rblist * rblist_first(const struct rblist *rblist)
{
    return rblist->next;
}

/*
 * Return the last node of a rblist.
 */
static inline struct rblist * rblist_last(const struct rblist *rblist)
{
    return rblist->prev;
}

/*
 * Return the node next to the given node.
 */
static inline struct rblist * rblist_next(const struct rblist *node)
{
    return node->next;
}

/*
 * Return the node previous to the given node.
 */
static inline struct rblist * rblist_prev(const struct rblist *node)
{
    return node->prev;
}

/*
 * Get the first entry of a rblist.
 */
#define rblist_first_entry(rblist, type, member) \
    rblist_entry(rblist_first(rblist), type, member)

/*
 * Get the last entry of a rblist.
 */
#define rblist_last_entry(rblist, type, member) \
    rblist_entry(rblist_last(rblist), type, member)

/*
 * Return true if node is after the last or before the first node of the rblist.
 */
static inline int rblist_end(const struct rblist *rblist, const struct rblist *node)
{
    return rblist == node;
}

/*
 * Return true if rblist is empty.
 */
static inline int rblist_empty(const struct rblist *rblist)
{
    return rblist == rblist->next;
}

/*
 * Return true if rblist contains exactly one node.
 */
static inline int rblist_singular(const struct rblist *rblist)
{
    return (rblist != rblist->next) && (rblist->next == rblist->prev);
}

/*
 * Split rblist2 by moving its nodes up to (but not including) the given
 * node into rblist1 (which can be in a stale state).
 *
 * If rblist2 is empty, or node is rblist2 or rblist2->next, nothing is done.
 */
static inline void rblist_split(struct rblist *rblist1, struct rblist *rblist2,
                              struct rblist *node)
{
    if (rblist_empty(rblist2) || (rblist2->next == node) || rblist_end(rblist2, node))
        return;

    rblist1->next = rblist2->next;
    rblist1->next->prev = rblist1;

    rblist1->prev = node->prev;
    node->prev->next = rblist1;

    rblist2->next = node;
    node->prev = rblist2;
}

/*
 * Append the nodes of rblist2 at the end of rblist1.
 *
 * After completion, rblist2 is stale.
 */
static inline void rblist_concat(struct rblist *rblist1, const struct rblist *rblist2)
{
    struct rblist *last1, *first2, *last2;

    if (rblist_empty(rblist2))
        return;

    last1 = rblist1->prev;
    first2 = rblist2->next;
    last2 = rblist2->prev;

    last1->next = first2;
    first2->prev = last1;

    last2->next = rblist1;
    rblist1->prev = last2;
}

/*
 * Set the new head of a rblist.
 *
 * This function is an optimized version of :
 * rblist_init(&new_rblist);
 * rblist_concat(&new_rblist, &old_rblist);
 *
 * After completion, old_head is stale.
 */
static inline void rblist_set_head(struct rblist *new_head,
                                 const struct rblist *old_head)
{
    if (rblist_empty(old_head)) {
        rblist_init(new_head);
        return;
    }

    *new_head = *old_head;
    new_head->next->prev = new_head;
    new_head->prev->next = new_head;
}

/*
 * Add a node between two nodes.
 */
static inline void rblist_add(struct rblist *prev, struct rblist *next,
                            struct rblist *node)
{
    next->prev = node;
    node->next = next;

    prev->next = node;
    node->prev = prev;
}

/*
 * Insert a node at the head of a rblist.
 */
static inline void rblist_insert_head(struct rblist *rblist, struct rblist *node)
{
    rblist_add(rblist, rblist->next, node);
}

/*
 * Insert a node at the tail of a rblist.
 */
static inline void rblist_insert_tail(struct rblist *rblist, struct rblist *node)
{
    rblist_add(rblist->prev, rblist, node);
}

/*
 * Insert a node before another node.
 */
static inline void rblist_insert_before(struct rblist *next, struct rblist *node)
{
    rblist_add(next->prev, next, node);
}

/*
 * Insert a node after another node.
 */
static inline void rblist_insert_after(struct rblist *prev, struct rblist *node)
{
    rblist_add(prev, prev->next, node);
}

/*
 * Remove a node from a rblist.
 *
 * After completion, the node is stale.
 */
static inline void rblist_remove(struct rblist *node)
{
    node->prev->next = node->next;
    node->next->prev = node->prev;
}

/*
 * Forge a loop to process all nodes of a rblist.
 *
 * The node must not be altered during the loop.
 */
#define rblist_for_each(rblist, node)   \
for (node = rblist_first(rblist);       \
     !rblist_end(rblist, node);         \
     node = rblist_next(node))

/*
 * Forge a loop to process all nodes of a rblist.
 */
#define rblist_for_each_safe(rblist, node, tmp)             \
for (node = rblist_first(rblist), tmp = rblist_next(node);    \
     !rblist_end(rblist, node);                             \
     node = tmp, tmp = rblist_next(node))

/*
 * Version of rblist_for_each() that processes nodes backward.
 */
#define rblist_for_each_reverse(rblist, node)   \
for (node = rblist_last(rblist);                \
     !rblist_end(rblist, node);                 \
     node = rblist_prev(node))

/*
 * Version of rblist_for_each_safe() that processes nodes backward.
 */
#define rblist_for_each_reverse_safe(rblist, node, tmp) \
for (node = rblist_last(rblist), tmp = rblist_prev(node); \
     !rblist_end(rblist, node);                         \
     node = tmp, tmp = rblist_prev(node))

/*
 * Forge a loop to process all entries of a rblist.
 *
 * The entry node must not be altered during the loop.
 */
#define rblist_for_each_entry(rblist, entry, member)                    \
for (entry = rblist_entry(rblist_first(rblist), typeof(*entry), member);  \
     !rblist_end(rblist, &entry->member);                               \
     entry = rblist_entry(rblist_next(&entry->member), typeof(*entry),  \
                        member))

/*
 * Forge a loop to process all entries of a rblist.
 */
#define rblist_for_each_entry_safe(rblist, entry, tmp, member)          \
for (entry = rblist_entry(rblist_first(rblist), typeof(*entry), member),  \
       tmp = rblist_entry(rblist_next(&entry->member), typeof(*entry),  \
                        member);                                    \
     !rblist_end(rblist, &entry->member);                               \
     entry = tmp, tmp = rblist_entry(rblist_next(&entry->member),       \
                                   typeof(*entry), member))

/*
 * Version of rblist_for_each_entry() that processes entries backward.
 */
#define rblist_for_each_entry_reverse(rblist, entry, member)            \
for (entry = rblist_entry(rblist_last(rblist), typeof(*entry), member);   \
     !rblist_end(rblist, &entry->member);                               \
     entry = rblist_entry(rblist_prev(&entry->member), typeof(*entry),  \
                        member))

/*
 * Version of rblist_for_each_entry_safe() that processes entries backward.
 */
#define rblist_for_each_entry_reverse_safe(rblist, entry, tmp, member)  \
for (entry = rblist_entry(rblist_last(rblist), typeof(*entry), member),   \
       tmp = rblist_entry(rblist_prev(&entry->member), typeof(*entry),  \
                        member);                                    \
     !rblist_end(rblist, &entry->member);                               \
     entry = tmp, tmp = rblist_entry(rblist_prev(&entry->member),       \
                                   typeof(*entry), member))

#endif /* _KERN_rblist_H */