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1/*
2 * Statically sized hash table implementation
3 * (C) 2012 Sasha Levin <levinsasha928@gmail.com>
4 */
5
6#ifndef _LINUX_HASHTABLE_H
7#define _LINUX_HASHTABLE_H
8
9#include <linux/list.h>
10#include <linux/types.h>
11#include <linux/kernel.h>
12#include <linux/bitops.h>
13#include <linux/hash.h>
14#include <linux/log2.h>
15
16#ifndef ARRAY_SIZE
17#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
18#endif
19
20#define DEFINE_HASHTABLE(name, bits) \
21 struct hlist_head name[1 << (bits)] = \
22 { [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT }
23
24#define DECLARE_HASHTABLE(name, bits) \
25 struct hlist_head name[1 << (bits)]
26
27#define HASH_SIZE(name) (ARRAY_SIZE(name))
28#define HASH_BITS(name) ilog2(HASH_SIZE(name))
29
30/* Use hash_32 when possible to allow for fast 32bit hashing in 64bit kernels. */
31#define hash_min(val, bits) \
32 (sizeof(val) <= 4 ? hash_32(val, bits) : hash_long(val, bits))
33
34static inline void __hash_init(struct hlist_head *ht, unsigned int sz)
35{
36 unsigned int i;
37
38 for (i = 0; i < sz; i++)
39 INIT_HLIST_HEAD(&ht[i]);
40}
41
42/**
43 * hash_init - initialize a hash table
44 * @hashtable: hashtable to be initialized
45 *
46 * Calculates the size of the hashtable from the given parameter, otherwise
47 * same as hash_init_size.
48 *
49 * This has to be a macro since HASH_BITS() will not work on pointers since
50 * it calculates the size during preprocessing.
51 */
52#define hash_init(hashtable) __hash_init(hashtable, HASH_SIZE(hashtable))
53
54/**
55 * hash_add - add an object to a hashtable
56 * @hashtable: hashtable to add to
57 * @node: the &struct hlist_node of the object to be added
58 * @key: the key of the object to be added
59 */
60#define hash_add(hashtable, node, key) \
61 hlist_add_head(node, &hashtable[hash_min(key, HASH_BITS(hashtable))])
62
63/**
64 * hash_hashed - check whether an object is in any hashtable
65 * @node: the &struct hlist_node of the object to be checked
66 */
67static inline bool hash_hashed(struct hlist_node *node)
68{
69 return !hlist_unhashed(node);
70}
71
72static inline bool __hash_empty(struct hlist_head *ht, unsigned int sz)
73{
74 unsigned int i;
75
76 for (i = 0; i < sz; i++)
77 if (!hlist_empty(&ht[i]))
78 return false;
79
80 return true;
81}
82
83/**
84 * hash_empty - check whether a hashtable is empty
85 * @hashtable: hashtable to check
86 *
87 * This has to be a macro since HASH_BITS() will not work on pointers since
88 * it calculates the size during preprocessing.
89 */
90#define hash_empty(hashtable) __hash_empty(hashtable, HASH_SIZE(hashtable))
91
92/**
93 * hash_del - remove an object from a hashtable
94 * @node: &struct hlist_node of the object to remove
95 */
96static inline void hash_del(struct hlist_node *node)
97{
98 hlist_del_init(node);
99}
100
101/**
102 * hash_for_each - iterate over a hashtable
103 * @name: hashtable to iterate
104 * @bkt: integer to use as bucket loop cursor
105 * @obj: the type * to use as a loop cursor for each entry
106 * @member: the name of the hlist_node within the struct
107 */
108#define hash_for_each(name, bkt, obj, member) \
109 for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
110 (bkt)++)\
111 hlist_for_each_entry(obj, &name[bkt], member)
112
113/**
114 * hash_for_each_safe - iterate over a hashtable safe against removal of
115 * hash entry
116 * @name: hashtable to iterate
117 * @bkt: integer to use as bucket loop cursor
118 * @tmp: a &struct used for temporary storage
119 * @obj: the type * to use as a loop cursor for each entry
120 * @member: the name of the hlist_node within the struct
121 */
122#define hash_for_each_safe(name, bkt, tmp, obj, member) \
123 for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
124 (bkt)++)\
125 hlist_for_each_entry_safe(obj, tmp, &name[bkt], member)
126
127/**
128 * hash_for_each_possible - iterate over all possible objects hashing to the
129 * same bucket
130 * @name: hashtable to iterate
131 * @obj: the type * to use as a loop cursor for each entry
132 * @member: the name of the hlist_node within the struct
133 * @key: the key of the objects to iterate over
134 */
135#define hash_for_each_possible(name, obj, member, key) \
136 hlist_for_each_entry(obj, &name[hash_min(key, HASH_BITS(name))], member)
137
138/**
139 * hash_for_each_possible_safe - iterate over all possible objects hashing to the
140 * same bucket safe against removals
141 * @name: hashtable to iterate
142 * @obj: the type * to use as a loop cursor for each entry
143 * @tmp: a &struct used for temporary storage
144 * @member: the name of the hlist_node within the struct
145 * @key: the key of the objects to iterate over
146 */
147#define hash_for_each_possible_safe(name, obj, tmp, member, key) \
148 hlist_for_each_entry_safe(obj, tmp,\
149 &name[hash_min(key, HASH_BITS(name))], member)
150
151
152#endif