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
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
41 static char sccsid[] = "@(#)hash.c 8.1 (Berkeley) 6/6/93";
43 static const char rcsid[] =
44 "$FreeBSD: src/usr.bin/make/hash.c,v 1.9 1999/09/11 13:08:01 hoek Exp $";
50 * This module contains routines to manipulate a hash table.
51 * See hash.h for a definition of the structure of the hash
52 * table. Hash tables grow automatically as the amount of
53 * information increases.
60 * Forward references to local procedures that are used before they're
64 static void RebuildTable __P((Hash_Table *));
67 * The following defines the ratio of # entries to # buckets
68 * at which we rebuild the table to make it larger.
71 #define rebuildLimit 8
74 *---------------------------------------------------------
78 * This routine just sets up the hash table.
84 * Memory is allocated for the initial bucket area.
86 *---------------------------------------------------------
90 Hash_InitTable(t, numBuckets)
91 register Hash_Table *t; /* Structure to use to hold table. */
92 int numBuckets; /* How many buckets to create for starters.
93 * This number is rounded up to a power of
94 * two. If <= 0, a reasonable default is
95 * chosen. The table will grow in size later
99 register struct Hash_Entry **hp;
102 * Round up the size to a power of two.
107 for (i = 2; i < numBuckets; i <<= 1)
113 t->bucketPtr = hp = (struct Hash_Entry **)emalloc(sizeof(*hp) * i);
119 *---------------------------------------------------------
121 * Hash_DeleteTable --
123 * This routine removes everything from a hash table
124 * and frees up the memory space it occupied (except for
125 * the space in the Hash_Table structure).
131 * Lots of memory is freed up.
133 *---------------------------------------------------------
140 register struct Hash_Entry **hp, *h, *nexth = NULL;
143 for (hp = t->bucketPtr, i = t->size; --i >= 0;) {
144 for (h = *hp++; h != NULL; h = nexth) {
149 free((char *)t->bucketPtr);
152 * Set up the hash table to cause memory faults on any future access
153 * attempts until re-initialization.
159 *---------------------------------------------------------
163 * Searches a hash table for an entry corresponding to key.
166 * The return value is a pointer to the entry for key,
167 * if key was present in the table. If key was not
168 * present, NULL is returned.
173 *---------------------------------------------------------
177 Hash_FindEntry(t, key)
178 Hash_Table *t; /* Hash table to search. */
179 char *key; /* A hash key. */
181 register Hash_Entry *e;
185 for (h = 0, p = key; *p;)
186 h = (h << 5) - h + *p++;
188 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next)
189 if (e->namehash == h && strcmp(e->name, p) == 0)
195 *---------------------------------------------------------
197 * Hash_CreateEntry --
199 * Searches a hash table for an entry corresponding to
200 * key. If no entry is found, then one is created.
203 * The return value is a pointer to the entry. If *newPtr
204 * isn't NULL, then *newPtr is filled in with TRUE if a
205 * new entry was created, and FALSE if an entry already existed
206 * with the given key.
209 * Memory may be allocated, and the hash buckets may be modified.
210 *---------------------------------------------------------
214 Hash_CreateEntry(t, key, newPtr)
215 register Hash_Table *t; /* Hash table to search. */
216 char *key; /* A hash key. */
217 Boolean *newPtr; /* Filled in with TRUE if new entry created,
218 * FALSE otherwise. */
220 register Hash_Entry *e;
224 struct Hash_Entry **hp;
227 * Hash the key. As a side effect, save the length (strlen) of the
228 * key in case we need to create the entry.
230 for (h = 0, p = key; *p;)
231 h = (h << 5) - h + *p++;
234 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) {
235 if (e->namehash == h && strcmp(e->name, p) == 0) {
243 * The desired entry isn't there. Before allocating a new entry,
244 * expand the table if necessary (and this changes the resulting
247 if (t->numEntries >= rebuildLimit * t->size)
249 e = (Hash_Entry *) emalloc(sizeof(*e) + keylen);
250 hp = &t->bucketPtr[h & t->mask];
253 e->clientData = NULL;
255 (void) strcpy(e->name, p);
264 *---------------------------------------------------------
266 * Hash_DeleteEntry --
268 * Delete the given hash table entry and free memory associated with
275 * Hash chain that entry lives in is modified and memory is freed.
277 *---------------------------------------------------------
281 Hash_DeleteEntry(t, e)
285 register Hash_Entry **hp, *p;
289 for (hp = &t->bucketPtr[e->namehash & t->mask];
290 (p = *hp) != NULL; hp = &p->next) {
298 (void) write(2, "bad call to Hash_DeleteEntry\n", 29);
303 *---------------------------------------------------------
306 * This procedure sets things up for a complete search
307 * of all entries recorded in the hash table.
310 * The return value is the address of the first entry in
311 * the hash table, or NULL if the table is empty.
314 * The information in searchPtr is initialized so that successive
315 * calls to Hash_Next will return successive HashEntry's
318 *---------------------------------------------------------
322 Hash_EnumFirst(t, searchPtr)
323 Hash_Table *t; /* Table to be searched. */
324 register Hash_Search *searchPtr;/* Area in which to keep state
327 searchPtr->tablePtr = t;
328 searchPtr->nextIndex = 0;
329 searchPtr->hashEntryPtr = NULL;
330 return Hash_EnumNext(searchPtr);
334 *---------------------------------------------------------
337 * This procedure returns successive entries in the hash table.
340 * The return value is a pointer to the next HashEntry
341 * in the table, or NULL when the end of the table is
345 * The information in searchPtr is modified to advance to the
348 *---------------------------------------------------------
352 Hash_EnumNext(searchPtr)
353 register Hash_Search *searchPtr; /* Area used to keep state about
356 register Hash_Entry *e;
357 Hash_Table *t = searchPtr->tablePtr;
360 * The hashEntryPtr field points to the most recently returned
361 * entry, or is nil if we are starting up. If not nil, we have
362 * to start at the next one in the chain.
364 e = searchPtr->hashEntryPtr;
368 * If the chain ran out, or if we are starting up, we need to
369 * find the next nonempty chain.
372 if (searchPtr->nextIndex >= t->size)
374 e = t->bucketPtr[searchPtr->nextIndex++];
376 searchPtr->hashEntryPtr = e;
381 *---------------------------------------------------------
384 * This local routine makes a new hash table that
385 * is larger than the old one.
391 * The entire hash table is moved, so any bucket numbers
392 * from the old table are invalid.
394 *---------------------------------------------------------
399 register Hash_Table *t;
401 register Hash_Entry *e, *next = NULL, **hp, **xp;
402 register int i, mask;
403 register Hash_Entry **oldhp;
406 oldhp = t->bucketPtr;
407 oldsize = i = t->size;
410 t->mask = mask = i - 1;
411 t->bucketPtr = hp = (struct Hash_Entry **) emalloc(sizeof(*hp) * i);
414 for (hp = oldhp, i = oldsize; --i >= 0;) {
415 for (e = *hp++; e != NULL; e = next) {
417 xp = &t->bucketPtr[e->namehash & mask];