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630 lines
35 KiB
C
630 lines
35 KiB
C
/* Copyright (c) 2002, Christopher Clark.
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* Copyright (c) 2005-2006, Nick Mathewson.
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* Copyright (c) 2007-2019, 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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/*
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These macros provide an intrustive implementation for a typesafe chaining
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hash table, loosely based on the BSD tree.h and queue.h macros. Here's
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how to use them.
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First, pick a the structure that you'll be storing in the hashtable. Let's
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say that's "struct dinosaur". To this structure, you add an HT_ENTRY()
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member, as such:
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struct dinosaur {
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HT_ENTRY(dinosaur) node; // The name inside the () must match the
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// struct.
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// These are just fields from the dinosaur structure...
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long dinosaur_id;
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char *name;
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long age;
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int is_ornithischian;
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int is_herbivorous;
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};
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You can declare the hashtable itself as:
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HT_HEAD(dinosaur_ht, dinosaur);
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This declares a new 'struct dinosaur_ht' type.
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Now you need to declare two functions to help implement the hashtable: one
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compares two dinosaurs for equality, and one computes the hash of a
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dinosaur. Let's say that two dinosaurs are equal if they have the same ID
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and name.
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int
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dinosaurs_equal(const struct dinosaur *d1, const struct dinosaur *d2)
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{
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return d1->dinosaur_id == d2->dinosaur_id &&
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0 == strcmp(d1->name, d2->name);
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}
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unsigned
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dinosaur_hash(const struct dinosaur *d)
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{
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// This is a very bad hash function. Use siphash24g instead.
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return (d->dinosaur_id + d->name[0] ) * 1337 + d->name[1] * 1337;
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}
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Now you'll need to declare the functions that manipulate the hash table.
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To do this, you put this declaration either in a header file, or inside
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a regular module, depending on what visibility you want.
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HT_PROTOTYPE(dinosaur_ht, // The name of the hashtable struct
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dinosaur, // The name of the element struct,
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node, // The name of HT_ENTRY member
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dinosaur_hash, dinosaurs_equal);
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Later, inside a C function, you use this macro to declare the hashtable
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functions.
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HT_GENERATE2(dinosaur_ht, dinosaur, node, dinosaur_hash, dinosaurs_equal,
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0.6, tor_reallocarray, tor_free_);
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Note the use of tor_free_, not tor_free. The 0.6 is magic.
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Now you can use the hashtable! You can initialize one with
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struct dinosaur_ht my_dinos = HT_INITIALIZER();
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Or create one in core with
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struct dinosaur_ht *dinos = tor_malloc(sizeof(dinosaur_ht));
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HT_INIT(dinosaur_ht, dinos);
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To the hashtable, you use the HT_FOO(dinosaur_ht, ...) macros. For
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example, to put new_dino into dinos, you say:
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HT_REPLACE(dinosaur_ht, dinos, new_dino);
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If you're searching for an element, you need to use a dummy 'key' element in
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the search. For example.
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struct dinosaur dino_key;
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dino_key.dinosaur_id = 12345;
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dino_key.name = tor_strdup("Atrociraptor");
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struct dinosaur *found = HT_FIND(dinosaurs_ht, dinos, &dino_key);
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Have fun with your hash table!
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*/
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#ifndef HT_H_INCLUDED_
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#define HT_H_INCLUDED_
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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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#ifdef HT_NO_CACHE_HASH_VALUES
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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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}
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#else
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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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#endif
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/* || 0 is for -Wparentheses-equality (-Wall?) appeasement under clang */
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#define HT_EMPTY(head) \
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(((head)->hth_n_entries == 0) || 0)
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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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#define HT_REP_IS_BAD_(name, head) name##_HT_REP_IS_BAD_(head)
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#define HT_FOREACH_FN(name, head, fn, data) \
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name##_HT_FOREACH_FN((head), (fn), (data))
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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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#if 0
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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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#endif
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#ifndef HT_NO_CACHE_HASH_VALUES
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#define HT_SET_HASH_(elm, field, hashfn) \
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do { (elm)->field.hte_hash = hashfn(elm); } while (0)
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#define HT_SET_HASHVAL_(elm, field, val) \
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do { (elm)->field.hte_hash = (val); } while (0)
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#define HT_ELT_HASH_(elm, field, hashfn) \
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((elm)->field.hte_hash)
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#else
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#define HT_SET_HASH_(elm, field, hashfn) \
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((void)0)
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#define HT_ELT_HASH_(elm, field, hashfn) \
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(hashfn(elm))
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#define HT_SET_HASHVAL_(elm, field, val) \
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((void)0)
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#endif
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#define HT_BUCKET_NUM_(head, field, elm, hashfn) \
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(HT_ELT_HASH_(elm,field,hashfn) % head->hth_table_length)
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/* Helper: alias for the bucket containing 'elm'. */
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#define HT_BUCKET_(head, field, elm, hashfn) \
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((head)->hth_table[HT_BUCKET_NUM_(head, field, elm, hashfn)])
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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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#ifndef HT_NDEBUG
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#include "lib/err/torerr.h"
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#define HT_ASSERT_(x) raw_assert(x)
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#else
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#define HT_ASSERT_(x) (void)0
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#endif
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/* Macro put at the end of the end of a macro definition so that it
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* consumes the following semicolon at file scope. Used only inside ht.h. */
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#define HT_EAT_SEMICOLON__ struct ht_semicolon_eater
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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, hashfn); \
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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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ATTR_UNUSED 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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ATTR_UNUSED 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, hashfn); \
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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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ATTR_UNUSED 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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HT_ASSERT_(p != NULL); /* this holds because we called HT_GROW */ \
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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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ATTR_UNUSED 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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ATTR_UNUSED 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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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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if (fn(*p, data)) { \
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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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ATTR_UNUSED 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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HT_ASSERT_(b == \
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HT_BUCKET_NUM_(head,field,head->hth_table[b],hashfn)); \
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return &head->hth_table[b]; \
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} \
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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, or use \
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* HT_NEXT_RMV instead. \
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*/ \
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ATTR_UNUSED 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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HT_ASSERT_(HT_BUCKET_NUM_(head,field,*elm,hashfn) == \
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HT_BUCKET_NUM_(head,field,(*elm)->field.hte_next,hashfn)); \
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return &(*elm)->field.hte_next; \
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} else { \
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unsigned b = HT_BUCKET_NUM_(head,field,*elm,hashfn)+1; \
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while (b < head->hth_table_length) { \
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if (head->hth_table[b]) { \
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HT_ASSERT_(b == \
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HT_BUCKET_NUM_(head,field,head->hth_table[b],hashfn)); \
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return &head->hth_table[b]; \
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} \
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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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/* As HT_NEXT, but also remove the current element 'elm' from the \
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* table. */ \
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ATTR_UNUSED 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 = HT_ELT_HASH_(*elm, field, hashfn); \
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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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HT_EAT_SEMICOLON__
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#define HT_GENERATE2(name, type, field, hashfn, eqfn, load, reallocarrayfn, \
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freefn) \
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/* Primes that aren't too far from powers of two. We stop at */ \
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/* P=402653189 because P*sizeof(void*) is less than SSIZE_MAX */ \
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/* even on a 32-bit platform. */ \
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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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}; \
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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 = reallocarrayfn(NULL, new_len, sizeof(struct type*)))) { \
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unsigned b; \
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memset(new_table, 0, new_len*sizeof(struct type*)); \
|
|
for (b = 0; b < head->hth_table_length; ++b) { \
|
|
struct type *elm, *next; \
|
|
unsigned b2; \
|
|
elm = head->hth_table[b]; \
|
|
while (elm) { \
|
|
next = elm->field.hte_next; \
|
|
b2 = HT_ELT_HASH_(elm, field, hashfn) % new_len; \
|
|
elm->field.hte_next = new_table[b2]; \
|
|
new_table[b2] = elm; \
|
|
elm = next; \
|
|
} \
|
|
} \
|
|
if (head->hth_table) \
|
|
freefn(head->hth_table); \
|
|
head->hth_table = new_table; \
|
|
} else { \
|
|
unsigned b, b2; \
|
|
new_table = reallocarrayfn(head->hth_table, new_len, sizeof(struct type*)); \
|
|
if (!new_table) return -1; \
|
|
memset(new_table + head->hth_table_length, 0, \
|
|
(new_len - head->hth_table_length)*sizeof(struct type*)); \
|
|
for (b=0; b < head->hth_table_length; ++b) { \
|
|
struct type *e, **pE; \
|
|
for (pE = &new_table[b], e = *pE; e != NULL; e = *pE) { \
|
|
b2 = HT_ELT_HASH_(e, field, hashfn) % new_len; \
|
|
if (b2 == b) { \
|
|
pE = &e->field.hte_next; \
|
|
} else { \
|
|
*pE = e->field.hte_next; \
|
|
e->field.hte_next = new_table[b2]; \
|
|
new_table[b2] = e; \
|
|
} \
|
|
} \
|
|
} \
|
|
head->hth_table = new_table; \
|
|
} \
|
|
head->hth_table_length = new_len; \
|
|
head->hth_prime_idx = prime_idx; \
|
|
head->hth_load_limit = new_load_limit; \
|
|
return 0; \
|
|
} \
|
|
/* Free all storage held by 'head'. Does not free 'head' itself, or \
|
|
* individual elements. */ \
|
|
void \
|
|
name##_HT_CLEAR(struct name *head) \
|
|
{ \
|
|
if (head->hth_table) \
|
|
freefn(head->hth_table); \
|
|
head->hth_table_length = 0; \
|
|
name##_HT_INIT(head); \
|
|
} \
|
|
/* Debugging helper: return false iff the representation of 'head' is \
|
|
* internally consistent. */ \
|
|
int \
|
|
name##_HT_REP_IS_BAD_(const struct name *head) \
|
|
{ \
|
|
unsigned n, i; \
|
|
struct type *elm; \
|
|
if (!head->hth_table_length) { \
|
|
if (!head->hth_table && !head->hth_n_entries && \
|
|
!head->hth_load_limit && head->hth_prime_idx == -1) \
|
|
return 0; \
|
|
else \
|
|
return 1; \
|
|
} \
|
|
if (!head->hth_table || head->hth_prime_idx < 0 || \
|
|
!head->hth_load_limit) \
|
|
return 2; \
|
|
if (head->hth_n_entries > head->hth_load_limit) \
|
|
return 3; \
|
|
if (head->hth_table_length != name##_PRIMES[head->hth_prime_idx]) \
|
|
return 4; \
|
|
if (head->hth_load_limit != (unsigned)(load*head->hth_table_length)) \
|
|
return 5; \
|
|
for (n = i = 0; i < head->hth_table_length; ++i) { \
|
|
for (elm = head->hth_table[i]; elm; elm = elm->field.hte_next) { \
|
|
if (HT_ELT_HASH_(elm, field, hashfn) != hashfn(elm)) \
|
|
return 1000 + i; \
|
|
if (HT_BUCKET_NUM_(head,field,elm,hashfn) != i) \
|
|
return 10000 + i; \
|
|
++n; \
|
|
} \
|
|
} \
|
|
if (n != head->hth_n_entries) \
|
|
return 6; \
|
|
return 0; \
|
|
} \
|
|
HT_EAT_SEMICOLON__
|
|
|
|
#define HT_GENERATE(name, type, field, hashfn, eqfn, load, mallocfn, \
|
|
reallocfn, freefn) \
|
|
static void * \
|
|
name##_reallocarray(void *arg, size_t a, size_t b) \
|
|
{ \
|
|
if ((b) && (a) > SIZE_MAX / (b)) \
|
|
return NULL; \
|
|
if (arg) \
|
|
return reallocfn((arg),(a)*(b)); \
|
|
else \
|
|
return mallocfn((a)*(b)); \
|
|
} \
|
|
HT_GENERATE2(name, type, field, hashfn, eqfn, load, \
|
|
name##_reallocarray, freefn)
|
|
|
|
/** Implements an over-optimized "find and insert if absent" block;
|
|
* not meant for direct usage by typical code, or usage outside the critical
|
|
* path.*/
|
|
#define HT_FIND_OR_INSERT_(name, field, hashfn, head, eltype, elm, var, y, n) \
|
|
{ \
|
|
struct name *var##_head_ = head; \
|
|
struct eltype **var; \
|
|
if (!var##_head_->hth_table || \
|
|
var##_head_->hth_n_entries >= var##_head_->hth_load_limit) \
|
|
name##_HT_GROW(var##_head_, var##_head_->hth_n_entries+1); \
|
|
HT_SET_HASH_((elm), field, hashfn); \
|
|
var = name##_HT_FIND_P_(var##_head_, (elm)); \
|
|
HT_ASSERT_(var); /* Holds because we called HT_GROW */ \
|
|
if (*var) { \
|
|
y; \
|
|
} else { \
|
|
n; \
|
|
} \
|
|
}
|
|
#define HT_FOI_INSERT_(field, head, elm, newent, var) \
|
|
{ \
|
|
HT_SET_HASHVAL_(newent, field, (elm)->field.hte_hash); \
|
|
newent->field.hte_next = NULL; \
|
|
*var = newent; \
|
|
++((head)->hth_n_entries); \
|
|
}
|
|
|
|
/*
|
|
* Copyright 2005, Nick Mathewson. Implementation logic is adapted from code
|
|
* by Christopher Clark, retrofit to allow drop-in memory management, and to
|
|
* use the same interface as Niels Provos's tree.h. This is probably still
|
|
* a derived work, so the original license below still applies.
|
|
*
|
|
* Copyright (c) 2002, Christopher Clark
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* * Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
*
|
|
* * Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* * Neither the name of the original author; nor the names of any contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
|
|
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
|
|
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
|
|
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
|
|
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
|
|
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
|
|
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
|
|
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#endif
|