88 lines
2.5 KiB
C
88 lines
2.5 KiB
C
/*
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* A hash table (hashtab) maintains associations between
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* key values and datum values. The type of the key values
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* and the type of the datum values is arbitrary. The
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* functions for hash computation and key comparison are
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* provided by the creator of the table.
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*
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* Author : Stephen Smalley, <sds@epoch.ncsc.mil>
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*/
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#ifndef _SS_HASHTAB_H_
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#define _SS_HASHTAB_H_
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#define HASHTAB_MAX_NODES 0xffffffff
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struct hashtab_node {
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void *key;
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void *datum;
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struct hashtab_node *next;
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};
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struct hashtab {
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struct hashtab_node **htable; /* hash table */
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u32 size; /* number of slots in hash table */
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u32 nel; /* number of elements in hash table */
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u32 (*hash_value)(struct hashtab *h, const void *key);
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/* hash function */
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int (*keycmp)(struct hashtab *h, const void *key1, const void *key2);
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/* key comparison function */
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};
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struct hashtab_info {
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u32 slots_used;
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u32 max_chain_len;
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};
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/*
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* Creates a new hash table with the specified characteristics.
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*
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* Returns NULL if insufficent space is available or
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* the new hash table otherwise.
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*/
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struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
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int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
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u32 size);
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/*
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* Inserts the specified (key, datum) pair into the specified hash table.
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*
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* Returns -ENOMEM on memory allocation error,
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* -EEXIST if there is already an entry with the same key,
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* -EINVAL for general errors or
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0 otherwise.
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*/
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int hashtab_insert(struct hashtab *h, void *k, void *d);
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/*
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* Searches for the entry with the specified key in the hash table.
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*
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* Returns NULL if no entry has the specified key or
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* the datum of the entry otherwise.
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*/
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void *hashtab_search(struct hashtab *h, const void *k);
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/*
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* Destroys the specified hash table.
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*/
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void hashtab_destroy(struct hashtab *h);
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/*
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* Applies the specified apply function to (key,datum,args)
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* for each entry in the specified hash table.
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*
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* The order in which the function is applied to the entries
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* is dependent upon the internal structure of the hash table.
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*
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* If apply returns a non-zero status, then hashtab_map will cease
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* iterating through the hash table and will propagate the error
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* return to its caller.
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*/
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int hashtab_map(struct hashtab *h,
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int (*apply)(void *k, void *d, void *args),
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void *args);
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/* Fill info with some hash table statistics */
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void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
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#endif /* _SS_HASHTAB_H */
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