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
  34 static 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  */
  67 static inline bool hash_hashed(struct hlist_node *node)
  68 {
  69         return !hlist_unhashed(node);
  70 }
  71
  72 static 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  */
  96 static 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