diff options
Diffstat (limited to 'headers/linux/hashtable.h')
| -rw-r--r-- | headers/linux/hashtable.h | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/headers/linux/hashtable.h b/headers/linux/hashtable.h new file mode 100644 index 0000000..6b987ae --- /dev/null +++ b/headers/linux/hashtable.h @@ -0,0 +1,187 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Statically sized hash table implementation + * (C) 2012 Sasha Levin <levinsasha928@gmail.com> + */ + +#ifndef _LINUX_HASHTABLE_H +#define _LINUX_HASHTABLE_H + +#include <math.h> +#include <stdint.h> +#include <stdbool.h> +#include <linux/hlist.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/compiler.h> + +#include "../lib/util/util.h" + +#define HASH_GOLDEN_RATIO_32 0x61C88647 +#define HASH_GOLDEN_RATIO_64 0x61C8864680B583EBull + +#if (__SIZEOF_LONG__ * __CHAR_BIT__) == 32 +#define HASH_GOLDEN_RATIO_PRIME HASH_GOLDEN_RATIO_32 +#define hash_long(val, bits) hash_32(val, bits) +#elif (__SIZEOF_LONG__ * __CHAR_BIT__) == 64 +#define hash_long(val, bits) hash_64(val, bits) +#define HASH_GOLDEN_RATIO_PRIME HASH_GOLDEN_RATIO_64 +#else +#error "Wordsize not 32 or 64" +#endif + +static inline uint32_t __hash_32(uint32_t val) +{ + return val * HASH_GOLDEN_RATIO_32; +} + +static inline uint32_t hash_32(uint32_t val, unsigned int bits) +{ + /* High bits are more random, so use them. */ + return __hash_32(val) >> (32 - bits); +} + +static inline uint32_t hash_64(uint64_t val, unsigned int bits) +{ +#if LONG_TYPE_SIZE * CHAR_BIT == 64 + /* 64x64-bit multiply is efficient on all 64-bit processors */ + return val * HASH_GOLDEN_RATIO_64 >> (64 - bits); +#else + /* Hash 64 bits using only 32x32-bit multiply. */ + return hash_32((uint32_t)val ^ __hash_32(val >> 32), bits); +#endif +} + +#define DEFINE_HASHTABLE(name, bits) \ + struct hlist_head name[1 << (bits)] = \ + { [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT } + +#define DECLARE_HASHTABLE(name, bits) \ + struct hlist_head name[1 << (bits)] + +#define HASH_SIZE(name) (ARRAY_SIZE(name)) +#define HASH_BITS(name) ilogb(HASH_SIZE(name)) + +/* Use hash_32 when possible to allow for fast 32bit hashing in 64bit kernels. */ +#define hash_min(val, bits) \ + (sizeof(val) <= 4 ? hash_32((uint32_t)val, bits) : hash_long((uint64_t)val, bits)) + +static inline void __hash_init(struct hlist_head *ht, unsigned int sz) +{ + unsigned int i; + + for (i = 0; i < sz; i++) + INIT_HLIST_HEAD(&ht[i]); +} + +/** + * hash_init - initialize a hash table + * @hashtable: hashtable to be initialized + * + * Calculates the size of the hashtable from the given parameter, otherwise + * same as hash_init_size. + * + * This has to be a macro since HASH_BITS() will not work on pointers since + * it calculates the size during preprocessing. + */ +#define hash_init(hashtable) __hash_init(hashtable, HASH_SIZE(hashtable)) + +/** + * hash_add - add an object to a hashtable + * @hashtable: hashtable to add to + * @node: the &struct hlist_node of the object to be added + * @key: the key of the object to be added + */ +#define hash_add(hashtable, node, key) \ + hlist_add_head(node, &hashtable[hash_min(key, HASH_BITS(hashtable))]) + +/** + * hash_hashed - check whether an object is in any hashtable + * @node: the &struct hlist_node of the object to be checked + */ +static inline bool hash_hashed(struct hlist_node *node) +{ + return !hlist_unhashed(node); +} + +static inline bool __hash_empty(struct hlist_head *ht, unsigned int sz) +{ + unsigned int i; + + for (i = 0; i < sz; i++) + if (!hlist_empty(&ht[i])) + return false; + + return true; +} + +/** + * hash_empty - check whether a hashtable is empty + * @hashtable: hashtable to check + * + * This has to be a macro since HASH_BITS() will not work on pointers since + * it calculates the size during preprocessing. + */ +#define hash_empty(hashtable) __hash_empty(hashtable, HASH_SIZE(hashtable)) + +/** + * hash_del - remove an object from a hashtable + * @node: &struct hlist_node of the object to remove + */ +static inline void hash_del(struct hlist_node *node) +{ + hlist_del_init(node); +} + +/** + * hash_for_each - iterate over a hashtable + * @name: hashtable to iterate + * @bkt: integer to use as bucket loop cursor + * @obj: the type * to use as a loop cursor for each entry + * @member: the name of the hlist_node within the struct + */ +#define hash_for_each(name, bkt, obj, member) \ + for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\ + (bkt)++)\ + hlist_for_each_entry(obj, &name[bkt], member) + +/** + * hash_for_each_safe - iterate over a hashtable safe against removal of + * hash entry + * @name: hashtable to iterate + * @bkt: integer to use as bucket loop cursor + * @tmp: a &struct used for temporary storage + * @obj: the type * to use as a loop cursor for each entry + * @member: the name of the hlist_node within the struct + */ +#define hash_for_each_safe(name, bkt, tmp, obj, member) \ + for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\ + (bkt)++)\ + hlist_for_each_entry_safe(obj, tmp, &name[bkt], member) + +/** + * hash_for_each_possible - iterate over all possible objects hashing to the + * same bucket + * @name: hashtable to iterate + * @obj: the type * to use as a loop cursor for each entry + * @member: the name of the hlist_node within the struct + * @key: the key of the objects to iterate over + */ +#define hash_for_each_possible(name, obj, member, key) \ + hlist_for_each_entry(obj, &name[hash_min(key, HASH_BITS(name))], member) + +/** + * hash_for_each_possible_safe - iterate over all possible objects hashing to the + * same bucket safe against removals + * @name: hashtable to iterate + * @obj: the type * to use as a loop cursor for each entry + * @tmp: a &struct used for temporary storage + * @member: the name of the hlist_node within the struct + * @key: the key of the objects to iterate over + */ +#define hash_for_each_possible_safe(name, obj, tmp, member, key) \ + hlist_for_each_entry_safe(obj, tmp,\ + &name[hash_min(key, HASH_BITS(name))], member) + + +#endif |