1/*
 2 * Copyright (C) 2011 STRATO AG
 3 * written by Arne Jansen <sensille@gmx.net>
 4 * Distributed under the GNU GPL license version 2.
 5 *
 6 */
 7
 8#ifndef __ULIST__
 9#define __ULIST__
10
11/*
12 * ulist is a generic data structure to hold a collection of unique u64
13 * values. The only operations it supports is adding to the list and
14 * enumerating it.
15 * It is possible to store an auxiliary value along with the key.
16 *
17 * The implementation is preliminary and can probably be sped up
18 * significantly. A first step would be to store the values in an rbtree
19 * as soon as ULIST_SIZE is exceeded.
20 */
21
22/*
23 * number of elements statically allocated inside struct ulist
24 */
25#define ULIST_SIZE 16
26
27struct ulist_iterator {
28	int i;
29};
30
31/*
32 * element of the list
33 */
34struct ulist_node {
35	u64 val;		/* value to store */
36	unsigned long aux;	/* auxiliary value saved along with the val */
37};
38
39struct ulist {
40	/*
41	 * number of elements stored in list
42	 */
43	unsigned long nnodes;
44
45	/*
46	 * number of nodes we already have room for
47	 */
48	unsigned long nodes_alloced;
49
50	/*
51	 * pointer to the array storing the elements. The first ULIST_SIZE
52	 * elements are stored inline. In this case the it points to int_nodes.
53	 * After exceeding ULIST_SIZE, dynamic memory is allocated.
54	 */
55	struct ulist_node *nodes;
56
57	/*
58	 * inline storage space for the first ULIST_SIZE entries
59	 */
60	struct ulist_node int_nodes[ULIST_SIZE];
61};
62
63void ulist_init(struct ulist *ulist);
64void ulist_fini(struct ulist *ulist);
65void ulist_reinit(struct ulist *ulist);
66struct ulist *ulist_alloc(gfp_t gfp_mask);
67void ulist_free(struct ulist *ulist);
68int ulist_add(struct ulist *ulist, u64 val, unsigned long aux,
69	      gfp_t gfp_mask);
70int ulist_add_merge(struct ulist *ulist, u64 val, unsigned long aux,
71		    unsigned long *old_aux, gfp_t gfp_mask);
72struct ulist_node *ulist_next(struct ulist *ulist,
73			      struct ulist_iterator *uiter);
74
75#define ULIST_ITER_INIT(uiter) ((uiter)->i = 0)
76
77#endif