1 /* $FreeBSD$ */ 2 /* $NetBSD: hash.c,v 1.1.1.1 1999/11/19 04:30:56 mrg Exp $ */ 3 4 /*- 5 * SPDX-License-Identifier: BSD-4-Clause 6 * 7 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California. 8 * Copyright (c) 1988, 1989 by Adam de Boor 9 * Copyright (c) 1989 by Berkeley Softworks 10 * All rights reserved. 11 * 12 * This code is derived from software contributed to Berkeley by 13 * Adam de Boor. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 3. All advertising materials mentioning features or use of this software 24 * must display the following acknowledgement: 25 * This product includes software developed by the University of 26 * California, Berkeley and its contributors. 27 * 4. Neither the name of the University nor the names of its contributors 28 * may be used to endorse or promote products derived from this software 29 * without specific prior written permission. 30 * 31 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 32 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 33 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 34 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 35 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 39 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 40 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 41 * SUCH DAMAGE. 42 */ 43 44 #ifdef MAKE_BOOTSTRAP 45 static char rcsid[] = "$NetBSD: hash.c,v 1.1.1.1 1999/11/19 04:30:56 mrg Exp $"; 46 #else 47 #include <sys/cdefs.h> 48 #ifndef lint 49 #if 0 50 static char sccsid[] = "@(#)hash.c 8.1 (Berkeley) 6/6/93"; 51 #else 52 __RCSID("$NetBSD: hash.c,v 1.1.1.1 1999/11/19 04:30:56 mrg Exp $"); 53 #endif 54 #endif /* not lint */ 55 #endif 56 57 #include <sys/types.h> 58 59 #include <stdlib.h> 60 #include <string.h> 61 #include <unistd.h> 62 63 /* hash.c -- 64 * 65 * This module contains routines to manipulate a hash table. 66 * See hash.h for a definition of the structure of the hash 67 * table. Hash tables grow automatically as the amount of 68 * information increases. 69 */ 70 #include "sprite.h" 71 #ifndef ORDER 72 #include "make.h" 73 #endif /* ORDER */ 74 #include "hash.h" 75 #include "ealloc.h" 76 77 /* 78 * Forward references to local procedures that are used before they're 79 * defined: 80 */ 81 82 static void RebuildTable(Hash_Table *); 83 84 /* 85 * The following defines the ratio of # entries to # buckets 86 * at which we rebuild the table to make it larger. 87 */ 88 89 #define rebuildLimit 8 90 91 /* 92 *--------------------------------------------------------- 93 * 94 * Hash_InitTable -- 95 * 96 * This routine just sets up the hash table. 97 * 98 * Results: 99 * None. 100 * 101 * Side Effects: 102 * Memory is allocated for the initial bucket area. 103 * 104 *--------------------------------------------------------- 105 */ 106 107 void 108 Hash_InitTable( 109 register Hash_Table *t, /* Structure to use to hold table. */ 110 int numBuckets) /* How many buckets to create for starters. 111 * This number is rounded up to a power of 112 * two. If <= 0, a reasonable default is 113 * chosen. The table will grow in size later 114 * as needed. */ 115 { 116 register int i; 117 register struct Hash_Entry **hp; 118 119 /* 120 * Round up the size to a power of two. 121 */ 122 if (numBuckets <= 0) 123 i = 16; 124 else { 125 for (i = 2; i < numBuckets; i <<= 1) 126 continue; 127 } 128 t->numEntries = 0; 129 t->size = i; 130 t->mask = i - 1; 131 t->bucketPtr = hp = (struct Hash_Entry **)emalloc(sizeof(*hp) * i); 132 while (--i >= 0) 133 *hp++ = NULL; 134 } 135 136 /* 137 *--------------------------------------------------------- 138 * 139 * Hash_DeleteTable -- 140 * 141 * This routine removes everything from a hash table 142 * and frees up the memory space it occupied (except for 143 * the space in the Hash_Table structure). 144 * 145 * Results: 146 * None. 147 * 148 * Side Effects: 149 * Lots of memory is freed up. 150 * 151 *--------------------------------------------------------- 152 */ 153 154 void 155 Hash_DeleteTable(Hash_Table *t) 156 { 157 register struct Hash_Entry **hp, *h, *nexth = NULL; 158 register int i; 159 160 for (hp = t->bucketPtr, i = t->size; --i >= 0;) { 161 for (h = *hp++; h != NULL; h = nexth) { 162 nexth = h->next; 163 free((char *)h); 164 } 165 } 166 free((char *)t->bucketPtr); 167 168 /* 169 * Set up the hash table to cause memory faults on any future access 170 * attempts until re-initialization. 171 */ 172 t->bucketPtr = NULL; 173 } 174 175 /* 176 *--------------------------------------------------------- 177 * 178 * Hash_FindEntry -- 179 * 180 * Searches a hash table for an entry corresponding to key. 181 * 182 * Results: 183 * The return value is a pointer to the entry for key, 184 * if key was present in the table. If key was not 185 * present, NULL is returned. 186 * 187 * Side Effects: 188 * None. 189 * 190 *--------------------------------------------------------- 191 */ 192 193 Hash_Entry * 194 Hash_FindEntry( 195 Hash_Table *t, /* Hash table to search. */ 196 char *key) /* A hash key. */ 197 { 198 register Hash_Entry *e; 199 register unsigned h; 200 register char *p; 201 202 for (h = 0, p = key; *p;) 203 h = (h << 5) - h + *p++; 204 p = key; 205 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) 206 if (e->namehash == h && strcmp(e->name, p) == 0) 207 return (e); 208 return (NULL); 209 } 210 211 /* 212 *--------------------------------------------------------- 213 * 214 * Hash_CreateEntry -- 215 * 216 * Searches a hash table for an entry corresponding to 217 * key. If no entry is found, then one is created. 218 * 219 * Results: 220 * The return value is a pointer to the entry. If *newPtr 221 * isn't NULL, then *newPtr is filled in with TRUE if a 222 * new entry was created, and FALSE if an entry already existed 223 * with the given key. 224 * 225 * Side Effects: 226 * Memory may be allocated, and the hash buckets may be modified. 227 *--------------------------------------------------------- 228 */ 229 230 Hash_Entry * 231 Hash_CreateEntry( 232 register Hash_Table *t, /* Hash table to search. */ 233 char *key, /* A hash key. */ 234 Boolean *newPtr) /* Filled in with TRUE if new entry created, 235 * FALSE otherwise. */ 236 { 237 register Hash_Entry *e; 238 register unsigned h; 239 register char *p; 240 int keylen; 241 struct Hash_Entry **hp; 242 243 /* 244 * Hash the key. As a side effect, save the length (strlen) of the 245 * key in case we need to create the entry. 246 */ 247 for (h = 0, p = key; *p;) 248 h = (h << 5) - h + *p++; 249 keylen = p - key; 250 p = key; 251 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) { 252 if (e->namehash == h && strcmp(e->name, p) == 0) { 253 if (newPtr != NULL) 254 *newPtr = FALSE; 255 return (e); 256 } 257 } 258 259 /* 260 * The desired entry isn't there. Before allocating a new entry, 261 * expand the table if necessary (and this changes the resulting 262 * bucket chain). 263 */ 264 if (t->numEntries >= rebuildLimit * t->size) 265 RebuildTable(t); 266 e = (Hash_Entry *) emalloc(sizeof(*e) + keylen); 267 hp = &t->bucketPtr[h & t->mask]; 268 e->next = *hp; 269 *hp = e; 270 e->clientData = NULL; 271 e->namehash = h; 272 (void) strcpy(e->name, p); 273 t->numEntries++; 274 275 if (newPtr != NULL) 276 *newPtr = TRUE; 277 return (e); 278 } 279 280 /* 281 *--------------------------------------------------------- 282 * 283 * Hash_DeleteEntry -- 284 * 285 * Delete the given hash table entry and free memory associated with 286 * it. 287 * 288 * Results: 289 * None. 290 * 291 * Side Effects: 292 * Hash chain that entry lives in is modified and memory is freed. 293 * 294 *--------------------------------------------------------- 295 */ 296 297 void 298 Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e) 299 { 300 register Hash_Entry **hp, *p; 301 302 if (e == NULL) 303 return; 304 for (hp = &t->bucketPtr[e->namehash & t->mask]; 305 (p = *hp) != NULL; hp = &p->next) { 306 if (p == e) { 307 *hp = p->next; 308 free((char *)p); 309 t->numEntries--; 310 return; 311 } 312 } 313 (void)write(2, "bad call to Hash_DeleteEntry\n", 29); 314 abort(); 315 } 316 317 /* 318 *--------------------------------------------------------- 319 * 320 * Hash_EnumFirst -- 321 * This procedure sets things up for a complete search 322 * of all entries recorded in the hash table. 323 * 324 * Results: 325 * The return value is the address of the first entry in 326 * the hash table, or NULL if the table is empty. 327 * 328 * Side Effects: 329 * The information in searchPtr is initialized so that successive 330 * calls to Hash_Next will return successive HashEntry's 331 * from the table. 332 * 333 *--------------------------------------------------------- 334 */ 335 336 Hash_Entry * 337 Hash_EnumFirst( 338 Hash_Table *t, /* Table to be searched. */ 339 register Hash_Search *searchPtr)/* Area in which to keep state 340 * about search.*/ 341 { 342 searchPtr->tablePtr = t; 343 searchPtr->nextIndex = 0; 344 searchPtr->hashEntryPtr = NULL; 345 return Hash_EnumNext(searchPtr); 346 } 347 348 /* 349 *--------------------------------------------------------- 350 * 351 * Hash_EnumNext -- 352 * This procedure returns successive entries in the hash table. 353 * 354 * Results: 355 * The return value is a pointer to the next HashEntry 356 * in the table, or NULL when the end of the table is 357 * reached. 358 * 359 * Side Effects: 360 * The information in searchPtr is modified to advance to the 361 * next entry. 362 * 363 *--------------------------------------------------------- 364 */ 365 366 Hash_Entry * 367 Hash_EnumNext( 368 register Hash_Search *searchPtr) /* Area used to keep state about 369 search. */ 370 { 371 register Hash_Entry *e; 372 Hash_Table *t = searchPtr->tablePtr; 373 374 /* 375 * The hashEntryPtr field points to the most recently returned 376 * entry, or is nil if we are starting up. If not nil, we have 377 * to start at the next one in the chain. 378 */ 379 e = searchPtr->hashEntryPtr; 380 if (e != NULL) 381 e = e->next; 382 /* 383 * If the chain ran out, or if we are starting up, we need to 384 * find the next nonempty chain. 385 */ 386 while (e == NULL) { 387 if (searchPtr->nextIndex >= t->size) 388 return (NULL); 389 e = t->bucketPtr[searchPtr->nextIndex++]; 390 } 391 searchPtr->hashEntryPtr = e; 392 return (e); 393 } 394 395 /* 396 *--------------------------------------------------------- 397 * 398 * RebuildTable -- 399 * This local routine makes a new hash table that 400 * is larger than the old one. 401 * 402 * Results: 403 * None. 404 * 405 * Side Effects: 406 * The entire hash table is moved, so any bucket numbers 407 * from the old table are invalid. 408 * 409 *--------------------------------------------------------- 410 */ 411 412 static void 413 RebuildTable(register Hash_Table *t) 414 { 415 register Hash_Entry *e, *next = NULL, **hp, **xp; 416 register int i, mask; 417 register Hash_Entry **oldhp; 418 int oldsize; 419 420 oldhp = t->bucketPtr; 421 oldsize = i = t->size; 422 i <<= 1; 423 t->size = i; 424 t->mask = mask = i - 1; 425 t->bucketPtr = hp = (struct Hash_Entry **) emalloc(sizeof(*hp) * i); 426 while (--i >= 0) 427 *hp++ = NULL; 428 for (hp = oldhp, i = oldsize; --i >= 0;) { 429 for (e = *hp++; e != NULL; e = next) { 430 next = e->next; 431 xp = &t->bucketPtr[e->namehash & mask]; 432 e->next = *xp; 433 *xp = e; 434 } 435 } 436 free((char *)oldhp); 437 } 438