mirror of
https://gitlab.torproject.org/tpo/core/tor.git
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472 lines
28 KiB
C
472 lines
28 KiB
C
/* Copyright (c) 2002, Christopher Clark.
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* Copyright (c) 2005-2006, Nick Mathewson.
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* Copyright (c) 2007-2011, The Tor Project, Inc. */
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/* See license at end. */
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/* Based on ideas by Christopher Clark and interfaces from Niels Provos. */
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#ifndef _TOR_HT_H
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#define _TOR_HT_H
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#define HT_HEAD(name, type) \
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struct name { \
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/* The hash table itself. */ \
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struct type **hth_table; \
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/* How long is the hash table? */ \
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unsigned hth_table_length; \
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/* How many elements does the table contain? */ \
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unsigned hth_n_entries; \
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/* How many elements will we allow in the table before resizing it? */ \
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unsigned hth_load_limit; \
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/* Position of hth_table_length in the primes table. */ \
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int hth_prime_idx; \
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}
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#define HT_INITIALIZER() \
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{ NULL, 0, 0, 0, -1 }
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#define HT_ENTRY(type) \
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struct { \
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struct type *hte_next; \
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unsigned hte_hash; \
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}
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#define HT_EMPTY(head) \
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((head)->hth_n_entries == 0)
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/* Helper: alias for the bucket containing 'elm'. */
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#define _HT_BUCKET(head, field, elm) \
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((head)->hth_table[elm->field.hte_hash % head->hth_table_length])
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/* How many elements in 'head'? */
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#define HT_SIZE(head) \
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((head)->hth_n_entries)
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/* Return memory usage for a hashtable (not counting the entries themselves) */
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#define HT_MEM_USAGE(head) \
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(sizeof(*head) + (head)->hth_table_length * sizeof(void*))
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#define HT_FIND(name, head, elm) name##_HT_FIND((head), (elm))
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#define HT_INSERT(name, head, elm) name##_HT_INSERT((head), (elm))
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#define HT_REPLACE(name, head, elm) name##_HT_REPLACE((head), (elm))
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#define HT_REMOVE(name, head, elm) name##_HT_REMOVE((head), (elm))
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#define HT_START(name, head) name##_HT_START(head)
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#define HT_NEXT(name, head, elm) name##_HT_NEXT((head), (elm))
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#define HT_NEXT_RMV(name, head, elm) name##_HT_NEXT_RMV((head), (elm))
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#define HT_CLEAR(name, head) name##_HT_CLEAR(head)
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#define HT_INIT(name, head) name##_HT_INIT(head)
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/* Helper: */
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static INLINE unsigned
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ht_improve_hash(unsigned h)
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{
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/* Aim to protect against poor hash functions by adding logic here
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* - logic taken from java 1.4 hashtable source */
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h += ~(h << 9);
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h ^= ((h >> 14) | (h << 18)); /* >>> */
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h += (h << 4);
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h ^= ((h >> 10) | (h << 22)); /* >>> */
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return h;
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}
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#if 0
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/** Basic string hash function, from Java standard String.hashCode(). */
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static INLINE unsigned
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ht_string_hash(const char *s)
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{
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unsigned h = 0;
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int m = 1;
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while (*s) {
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h += ((signed char)*s++)*m;
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m = (m<<5)-1; /* m *= 31 */
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}
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return h;
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}
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#endif
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/** Basic string hash function, from Python's str.__hash__() */
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static INLINE unsigned
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ht_string_hash(const char *s)
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{
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unsigned h;
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const unsigned char *cp = (const unsigned char *)s;
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h = *cp << 7;
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while (*cp) {
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h = (1000003*h) ^ *cp++;
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}
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/* This conversion truncates the length of the string, but that's ok. */
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h ^= (unsigned)(cp-(const unsigned char*)s);
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return h;
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}
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#define _HT_SET_HASH(elm, field, hashfn) \
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(elm)->field.hte_hash = hashfn(elm)
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#define HT_FOREACH(x, name, head) \
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for ((x) = HT_START(name, head); \
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(x) != NULL; \
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(x) = HT_NEXT(name, head, x))
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#define HT_PROTOTYPE(name, type, field, hashfn, eqfn) \
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int name##_HT_GROW(struct name *ht, unsigned min_capacity); \
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void name##_HT_CLEAR(struct name *ht); \
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int _##name##_HT_REP_IS_BAD(const struct name *ht); \
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static INLINE void \
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name##_HT_INIT(struct name *head) { \
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head->hth_table_length = 0; \
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head->hth_table = NULL; \
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head->hth_n_entries = 0; \
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head->hth_load_limit = 0; \
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head->hth_prime_idx = -1; \
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} \
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/* Helper: returns a pointer to the right location in the table \
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* 'head' to find or insert the element 'elm'. */ \
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static INLINE struct type ** \
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_##name##_HT_FIND_P(struct name *head, struct type *elm) \
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{ \
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struct type **p; \
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if (!head->hth_table) \
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return NULL; \
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p = &_HT_BUCKET(head, field, elm); \
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while (*p) { \
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if (eqfn(*p, elm)) \
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return p; \
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p = &(*p)->field.hte_next; \
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} \
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return p; \
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} \
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/* Return a pointer to the element in the table 'head' matching 'elm', \
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* or NULL if no such element exists */ \
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static INLINE struct type * \
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name##_HT_FIND(const struct name *head, struct type *elm) \
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{ \
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struct type **p; \
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struct name *h = (struct name *) head; \
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_HT_SET_HASH(elm, field, hashfn); \
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p = _##name##_HT_FIND_P(h, elm); \
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return p ? *p : NULL; \
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} \
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/* Insert the element 'elm' into the table 'head'. Do not call this \
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* function if the table might already contain a matching element. */ \
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static INLINE void \
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name##_HT_INSERT(struct name *head, struct type *elm) \
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{ \
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struct type **p; \
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if (!head->hth_table || head->hth_n_entries >= head->hth_load_limit) \
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name##_HT_GROW(head, head->hth_n_entries+1); \
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++head->hth_n_entries; \
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_HT_SET_HASH(elm, field, hashfn); \
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p = &_HT_BUCKET(head, field, elm); \
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elm->field.hte_next = *p; \
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*p = elm; \
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} \
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/* Insert the element 'elm' into the table 'head'. If there already \
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* a matching element in the table, replace that element and return \
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* it. */ \
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static INLINE struct type * \
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name##_HT_REPLACE(struct name *head, struct type *elm) \
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{ \
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struct type **p, *r; \
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if (!head->hth_table || head->hth_n_entries >= head->hth_load_limit) \
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name##_HT_GROW(head, head->hth_n_entries+1); \
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_HT_SET_HASH(elm, field, hashfn); \
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p = _##name##_HT_FIND_P(head, elm); \
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r = *p; \
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*p = elm; \
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if (r && (r!=elm)) { \
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elm->field.hte_next = r->field.hte_next; \
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r->field.hte_next = NULL; \
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return r; \
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} else { \
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++head->hth_n_entries; \
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return NULL; \
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} \
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} \
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/* Remove any element matching 'elm' from the table 'head'. If such \
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* an element is found, return it; otherwise return NULL. */ \
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static INLINE struct type * \
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name##_HT_REMOVE(struct name *head, struct type *elm) \
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{ \
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struct type **p, *r; \
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_HT_SET_HASH(elm, field, hashfn); \
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p = _##name##_HT_FIND_P(head,elm); \
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if (!p || !*p) \
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return NULL; \
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r = *p; \
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*p = r->field.hte_next; \
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r->field.hte_next = NULL; \
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--head->hth_n_entries; \
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return r; \
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} \
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/* Invoke the function 'fn' on every element of the table 'head', \
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* using 'data' as its second argument. If the function returns \
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* nonzero, remove the most recently examined element before invoking \
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* the function again. */ \
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static INLINE void \
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name##_HT_FOREACH_FN(struct name *head, \
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int (*fn)(struct type *, void *), \
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void *data) \
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{ \
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unsigned idx; \
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int remove; \
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struct type **p, **nextp, *next; \
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if (!head->hth_table) \
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return; \
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for (idx=0; idx < head->hth_table_length; ++idx) { \
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p = &head->hth_table[idx]; \
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while (*p) { \
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nextp = &(*p)->field.hte_next; \
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next = *nextp; \
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remove = fn(*p, data); \
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if (remove) { \
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--head->hth_n_entries; \
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*p = next; \
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} else { \
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p = nextp; \
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} \
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} \
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} \
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} \
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/* Return a pointer to the first element in the table 'head', under \
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* an arbitrary order. This order is stable under remove operations, \
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* but not under others. If the table is empty, return NULL. */ \
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static INLINE struct type ** \
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name##_HT_START(struct name *head) \
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{ \
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unsigned b = 0; \
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while (b < head->hth_table_length) { \
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if (head->hth_table[b]) \
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return &head->hth_table[b]; \
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++b; \
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} \
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return NULL; \
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} \
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/* Return the next element in 'head' after 'elm', under the arbitrary \
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* order used by HT_START. If there are no more elements, return \
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* NULL. If 'elm' is to be removed from the table, you must call \
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* this function for the next value before you remove it. \
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*/ \
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static INLINE struct type ** \
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name##_HT_NEXT(struct name *head, struct type **elm) \
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{ \
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if ((*elm)->field.hte_next) { \
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return &(*elm)->field.hte_next; \
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} else { \
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unsigned b = ((*elm)->field.hte_hash % head->hth_table_length)+1; \
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while (b < head->hth_table_length) { \
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if (head->hth_table[b]) \
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return &head->hth_table[b]; \
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++b; \
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} \
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return NULL; \
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} \
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} \
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static INLINE struct type ** \
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name##_HT_NEXT_RMV(struct name *head, struct type **elm) \
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{ \
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unsigned h = (*elm)->field.hte_hash; \
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*elm = (*elm)->field.hte_next; \
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--head->hth_n_entries; \
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if (*elm) { \
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return elm; \
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} else { \
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unsigned b = (h % head->hth_table_length)+1; \
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while (b < head->hth_table_length) { \
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if (head->hth_table[b]) \
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return &head->hth_table[b]; \
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++b; \
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} \
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return NULL; \
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} \
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}
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#define HT_GENERATE(name, type, field, hashfn, eqfn, load, mallocfn, \
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reallocfn, freefn) \
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static unsigned name##_PRIMES[] = { \
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53, 97, 193, 389, \
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769, 1543, 3079, 6151, \
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12289, 24593, 49157, 98317, \
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196613, 393241, 786433, 1572869, \
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3145739, 6291469, 12582917, 25165843, \
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50331653, 100663319, 201326611, 402653189, \
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805306457, 1610612741 \
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}; \
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static unsigned name##_N_PRIMES = \
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(unsigned)(sizeof(name##_PRIMES)/sizeof(name##_PRIMES[0])); \
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/* Expand the internal table of 'head' until it is large enough to \
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* hold 'size' elements. Return 0 on success, -1 on allocation \
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* failure. */ \
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int \
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name##_HT_GROW(struct name *head, unsigned size) \
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{ \
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unsigned new_len, new_load_limit; \
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int prime_idx; \
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struct type **new_table; \
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if (head->hth_prime_idx == (int)name##_N_PRIMES - 1) \
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return 0; \
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if (head->hth_load_limit > size) \
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return 0; \
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prime_idx = head->hth_prime_idx; \
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do { \
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new_len = name##_PRIMES[++prime_idx]; \
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new_load_limit = (unsigned)(load*new_len); \
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} while (new_load_limit <= size && \
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prime_idx < (int)name##_N_PRIMES); \
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if ((new_table = mallocfn(new_len*sizeof(struct type*)))) { \
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unsigned b; \
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memset(new_table, 0, new_len*sizeof(struct type*)); \
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for (b = 0; b < head->hth_table_length; ++b) { \
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struct type *elm, *next; \
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unsigned b2; \
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elm = head->hth_table[b]; \
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while (elm) { \
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next = elm->field.hte_next; \
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b2 = elm->field.hte_hash % new_len; \
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elm->field.hte_next = new_table[b2]; \
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new_table[b2] = elm; \
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elm = next; \
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} \
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} \
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if (head->hth_table) \
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freefn(head->hth_table); \
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head->hth_table = new_table; \
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} else { \
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unsigned b, b2; \
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new_table = reallocfn(head->hth_table, new_len*sizeof(struct type*)); \
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if (!new_table) return -1; \
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memset(new_table + head->hth_table_length, 0, \
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(new_len - head->hth_table_length)*sizeof(struct type*)); \
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for (b=0; b < head->hth_table_length; ++b) { \
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struct type *e, **pE; \
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for (pE = &new_table[b], e = *pE; e != NULL; e = *pE) { \
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b2 = e->field.hte_hash % new_len; \
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if (b2 == b) { \
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pE = &e->field.hte_next; \
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} else { \
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*pE = e->field.hte_next; \
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e->field.hte_next = new_table[b2]; \
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new_table[b2] = e; \
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} \
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} \
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} \
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head->hth_table = new_table; \
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} \
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head->hth_table_length = new_len; \
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head->hth_prime_idx = prime_idx; \
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head->hth_load_limit = new_load_limit; \
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return 0; \
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} \
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/* Free all storage held by 'head'. Does not free 'head' itself, or \
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* individual elements. */ \
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void \
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name##_HT_CLEAR(struct name *head) \
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{ \
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if (head->hth_table) \
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freefn(head->hth_table); \
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head->hth_table_length = 0; \
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name##_HT_INIT(head); \
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} \
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/* Debugging helper: return false iff the representation of 'head' is \
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* internally consistent. */ \
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int \
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_##name##_HT_REP_IS_BAD(const struct name *head) \
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{ \
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unsigned n, i; \
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struct type *elm; \
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if (!head->hth_table_length) { \
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if (!head->hth_table && !head->hth_n_entries && \
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!head->hth_load_limit && head->hth_prime_idx == -1) \
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return 0; \
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else \
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return 1; \
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} \
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if (!head->hth_table || head->hth_prime_idx < 0 || \
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!head->hth_load_limit) \
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return 2; \
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if (head->hth_n_entries > head->hth_load_limit) \
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return 3; \
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if (head->hth_table_length != name##_PRIMES[head->hth_prime_idx]) \
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return 4; \
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if (head->hth_load_limit != (unsigned)(load*head->hth_table_length)) \
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return 5; \
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for (n = i = 0; i < head->hth_table_length; ++i) { \
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for (elm = head->hth_table[i]; elm; elm = elm->field.hte_next) { \
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if (elm->field.hte_hash != hashfn(elm)) \
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return 1000 + i; \
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if ((elm->field.hte_hash % head->hth_table_length) != i) \
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return 10000 + i; \
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++n; \
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} \
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} \
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if (n != head->hth_n_entries) \
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return 6; \
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return 0; \
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}
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/** Implements an over-optimized "find and insert if absent" block;
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* not meant for direct usage by typical code, or usage outside the critical
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* path.*/
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#define _HT_FIND_OR_INSERT(name, field, hashfn, head, eltype, elm, var, y, n) \
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{ \
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struct name *_##var##_head = head; \
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eltype **var; \
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if (!_##var##_head->hth_table || \
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_##var##_head->hth_n_entries >= _##var##_head->hth_load_limit) \
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name##_HT_GROW(_##var##_head, _##var##_head->hth_n_entries+1); \
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_HT_SET_HASH((elm), field, hashfn); \
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var = _##name##_HT_FIND_P(_##var##_head, (elm)); \
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if (*var) { \
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y; \
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} else { \
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n; \
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} \
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}
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#define _HT_FOI_INSERT(field, head, elm, newent, var) \
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{ \
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newent->field.hte_hash = (elm)->field.hte_hash; \
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newent->field.hte_next = NULL; \
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*var = newent; \
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++((head)->hth_n_entries); \
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}
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/*
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* Copyright 2005, Nick Mathewson. Implementation logic is adapted from code
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* by Christopher Clark, retrofit to allow drop-in memory management, and to
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* use the same interface as Niels Provos's HT_H. I'm not sure whether this
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* is a derived work any more, but whether it is or not, the license below
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* applies.
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*
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* Copyright (c) 2002, Christopher Clark
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* * Neither the name of the original author; nor the names of any contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#endif
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