2 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
3 * Copyright (c) 1988, 1989 by Adam de Boor
4 * Copyright (c) 1989 by Berkeley Softworks
7 * This code is derived from software contributed to Berkeley by
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38 * @(#)hash.c 8.1 (Berkeley) 6/6/93
39 * $FreeBSD: src/usr.bin/make/hash.c,v 1.9 1999/09/11 13:08:01 hoek Exp $
40 * $DragonFly: src/usr.bin/make/hash.c,v 1.3 2003/11/03 19:31:30 eirikn Exp $
45 * This module contains routines to manipulate a hash table.
46 * See hash.h for a definition of the structure of the hash
47 * table. Hash tables grow automatically as the amount of
48 * information increases.
55 * Forward references to local procedures that are used before they're
59 static void RebuildTable(Hash_Table *);
62 * The following defines the ratio of # entries to # buckets
63 * at which we rebuild the table to make it larger.
66 #define rebuildLimit 8
69 *---------------------------------------------------------
73 * This routine just sets up the hash table.
79 * Memory is allocated for the initial bucket area.
81 *---------------------------------------------------------
85 Hash_InitTable(t, numBuckets)
86 register Hash_Table *t; /* Structure to use to hold table. */
87 int numBuckets; /* How many buckets to create for starters.
88 * This number is rounded up to a power of
89 * two. If <= 0, a reasonable default is
90 * chosen. The table will grow in size later
94 register struct Hash_Entry **hp;
97 * Round up the size to a power of two.
102 for (i = 2; i < numBuckets; i <<= 1)
108 t->bucketPtr = hp = (struct Hash_Entry **)emalloc(sizeof(*hp) * i);
114 *---------------------------------------------------------
116 * Hash_DeleteTable --
118 * This routine removes everything from a hash table
119 * and frees up the memory space it occupied (except for
120 * the space in the Hash_Table structure).
126 * Lots of memory is freed up.
128 *---------------------------------------------------------
135 register struct Hash_Entry **hp, *h, *nexth = NULL;
138 for (hp = t->bucketPtr, i = t->size; --i >= 0;) {
139 for (h = *hp++; h != NULL; h = nexth) {
144 free((char *)t->bucketPtr);
147 * Set up the hash table to cause memory faults on any future access
148 * attempts until re-initialization.
154 *---------------------------------------------------------
158 * Searches a hash table for an entry corresponding to key.
161 * The return value is a pointer to the entry for key,
162 * if key was present in the table. If key was not
163 * present, NULL is returned.
168 *---------------------------------------------------------
172 Hash_FindEntry(t, key)
173 Hash_Table *t; /* Hash table to search. */
174 char *key; /* A hash key. */
176 register Hash_Entry *e;
180 for (h = 0, p = key; *p;)
181 h = (h << 5) - h + *p++;
183 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next)
184 if (e->namehash == h && strcmp(e->name, p) == 0)
190 *---------------------------------------------------------
192 * Hash_CreateEntry --
194 * Searches a hash table for an entry corresponding to
195 * key. If no entry is found, then one is created.
198 * The return value is a pointer to the entry. If *newPtr
199 * isn't NULL, then *newPtr is filled in with TRUE if a
200 * new entry was created, and FALSE if an entry already existed
201 * with the given key.
204 * Memory may be allocated, and the hash buckets may be modified.
205 *---------------------------------------------------------
209 Hash_CreateEntry(t, key, newPtr)
210 register Hash_Table *t; /* Hash table to search. */
211 char *key; /* A hash key. */
212 Boolean *newPtr; /* Filled in with TRUE if new entry created,
213 * FALSE otherwise. */
215 register Hash_Entry *e;
219 struct Hash_Entry **hp;
222 * Hash the key. As a side effect, save the length (strlen) of the
223 * key in case we need to create the entry.
225 for (h = 0, p = key; *p;)
226 h = (h << 5) - h + *p++;
229 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) {
230 if (e->namehash == h && strcmp(e->name, p) == 0) {
238 * The desired entry isn't there. Before allocating a new entry,
239 * expand the table if necessary (and this changes the resulting
242 if (t->numEntries >= rebuildLimit * t->size)
244 e = (Hash_Entry *) emalloc(sizeof(*e) + keylen);
245 hp = &t->bucketPtr[h & t->mask];
248 e->clientData = NULL;
250 (void) strcpy(e->name, p);
259 *---------------------------------------------------------
261 * Hash_DeleteEntry --
263 * Delete the given hash table entry and free memory associated with
270 * Hash chain that entry lives in is modified and memory is freed.
272 *---------------------------------------------------------
276 Hash_DeleteEntry(t, e)
280 register Hash_Entry **hp, *p;
284 for (hp = &t->bucketPtr[e->namehash & t->mask];
285 (p = *hp) != NULL; hp = &p->next) {
293 (void) write(2, "bad call to Hash_DeleteEntry\n", 29);
298 *---------------------------------------------------------
301 * This procedure sets things up for a complete search
302 * of all entries recorded in the hash table.
305 * The return value is the address of the first entry in
306 * the hash table, or NULL if the table is empty.
309 * The information in searchPtr is initialized so that successive
310 * calls to Hash_Next will return successive HashEntry's
313 *---------------------------------------------------------
317 Hash_EnumFirst(t, searchPtr)
318 Hash_Table *t; /* Table to be searched. */
319 register Hash_Search *searchPtr;/* Area in which to keep state
322 searchPtr->tablePtr = t;
323 searchPtr->nextIndex = 0;
324 searchPtr->hashEntryPtr = NULL;
325 return Hash_EnumNext(searchPtr);
329 *---------------------------------------------------------
332 * This procedure returns successive entries in the hash table.
335 * The return value is a pointer to the next HashEntry
336 * in the table, or NULL when the end of the table is
340 * The information in searchPtr is modified to advance to the
343 *---------------------------------------------------------
347 Hash_EnumNext(searchPtr)
348 register Hash_Search *searchPtr; /* Area used to keep state about
351 register Hash_Entry *e;
352 Hash_Table *t = searchPtr->tablePtr;
355 * The hashEntryPtr field points to the most recently returned
356 * entry, or is nil if we are starting up. If not nil, we have
357 * to start at the next one in the chain.
359 e = searchPtr->hashEntryPtr;
363 * If the chain ran out, or if we are starting up, we need to
364 * find the next nonempty chain.
367 if (searchPtr->nextIndex >= t->size)
369 e = t->bucketPtr[searchPtr->nextIndex++];
371 searchPtr->hashEntryPtr = e;
376 *---------------------------------------------------------
379 * This local routine makes a new hash table that
380 * is larger than the old one.
386 * The entire hash table is moved, so any bucket numbers
387 * from the old table are invalid.
389 *---------------------------------------------------------
394 register Hash_Table *t;
396 register Hash_Entry *e, *next = NULL, **hp, **xp;
397 register int i, mask;
398 register Hash_Entry **oldhp;
401 oldhp = t->bucketPtr;
402 oldsize = i = t->size;
405 t->mask = mask = i - 1;
406 t->bucketPtr = hp = (struct Hash_Entry **) emalloc(sizeof(*hp) * i);
409 for (hp = oldhp, i = oldsize; --i >= 0;) {
410 for (e = *hp++; e != NULL; e = next) {
412 xp = &t->bucketPtr[e->namehash & mask];