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#ifndef HASH_H
#define HASH_H
/* Hash table implementation from the GIT project. */
/* Copyright 2008 (C) Linus Torvalds, GPL version 2 */
/*
* These are some simple generic hash table helper functions.
* Not necessarily suitable for all users, but good for things
* where you want to just keep track of a list of things, and
* have a good hash to use on them.
*
* It keeps the hash table at roughly 50-75% free, so the memory
* cost of the hash table itself is roughly
*
* 3 * 2*sizeof(void *) * nr_of_objects
*
* bytes.
*
* FIXME: on 64-bit architectures, we waste memory. It would be
* good to have just 32-bit pointers, requiring a special allocator
* for hashed entries or something.
*/
#include <stdio.h>
#define alloc_nr(x) (((x) + 16) * 3 / 2)
#define INSERT_HASH_PROTOS(ops, table) \
do { \
void **pos = insert_hash((ops).key, &(ops), &(table)); \
/* We already had an entry there? */ \
if (pos) { \
(ops).next = *pos; \
*pos = &(ops); \
} \
} while (0)
struct hash_table_entry {
unsigned int hash;
void *ptr;
};
struct hash_table {
unsigned int size, nr;
struct hash_table_entry *array;
};
extern void *lookup_hash(unsigned int hash, const struct hash_table *table);
extern void **insert_hash(unsigned int hash, void *ptr,
struct hash_table *table);
extern void *remove_hash(unsigned int hash, void *ptr, void *ptr_next,
struct hash_table *table);
extern int for_each_hash(const struct hash_table *table, int (*fn)(void *));
extern int for_each_hash_int(const struct hash_table *table,
int (*fn)(void *, int), int arg);
extern void free_hash(struct hash_table *table);
static inline void init_hash(struct hash_table *table)
{
table->size = 0;
table->nr = 0;
table->array = NULL;
}
static inline unsigned char icase_hash(unsigned char c)
{
return c & ~((c & 0x40) >> 1);
}
static inline unsigned int hash_name(const char *name, int namelen)
{
unsigned int hash = 0x123;
do {
unsigned char c = *name++;
c = icase_hash(c);
hash = hash * 101 + c;
} while (--namelen);
return hash;
}
#endif /* HASH_H */
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