LXR linux/tools/include/linux/hashtable.h

   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
 153