1 /* $NetBSD: hash.c,v 1.19 2009/01/24 10:59:09 dsl Exp $ */ 2 3 /* 4 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Adam de Boor. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 /* 36 * Copyright (c) 1988, 1989 by Adam de Boor 37 * Copyright (c) 1989 by Berkeley Softworks 38 * All rights reserved. 39 * 40 * This code is derived from software contributed to Berkeley by 41 * Adam de Boor. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. All advertising materials mentioning features or use of this software 52 * must display the following acknowledgement: 53 * This product includes software developed by the University of 54 * California, Berkeley and its contributors. 55 * 4. Neither the name of the University nor the names of its contributors 56 * may be used to endorse or promote products derived from this software 57 * without specific prior written permission. 58 * 59 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 60 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 61 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 62 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 63 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 64 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 65 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 66 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 67 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 68 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 69 * SUCH DAMAGE. 70 */ 71 72 #ifndef MAKE_NATIVE 73 static char rcsid[] = "$NetBSD: hash.c,v 1.19 2009/01/24 10:59:09 dsl Exp $"; 74 #else 75 #include <sys/cdefs.h> 76 #ifndef lint 77 #if 0 78 static char sccsid[] = "@(#)hash.c 8.1 (Berkeley) 6/6/93"; 79 #else 80 __RCSID("$NetBSD: hash.c,v 1.19 2009/01/24 10:59:09 dsl Exp $"); 81 #endif 82 #endif /* not lint */ 83 #endif 84 85 /* hash.c -- 86 * 87 * This module contains routines to manipulate a hash table. 88 * See hash.h for a definition of the structure of the hash 89 * table. Hash tables grow automatically as the amount of 90 * information increases. 91 */ 92 #include "sprite.h" 93 #include "make.h" 94 #include "hash.h" 95 96 /* 97 * Forward references to local procedures that are used before they're 98 * defined: 99 */ 100 101 static void RebuildTable(Hash_Table *); 102 103 /* 104 * The following defines the ratio of # entries to # buckets 105 * at which we rebuild the table to make it larger. 106 */ 107 108 #define rebuildLimit 3 109 110 /* 111 *--------------------------------------------------------- 112 * 113 * Hash_InitTable -- 114 * 115 * This routine just sets up the hash table. 116 * 117 * Input: 118 * t Structure to to hold table. 119 * numBuckets How many buckets to create for starters. This 120 * number is rounded up to a power of two. If 121 * <= 0, a reasonable default is chosen. The 122 * table will grow in size later as needed. 123 * 124 * Results: 125 * None. 126 * 127 * Side Effects: 128 * Memory is allocated for the initial bucket area. 129 * 130 *--------------------------------------------------------- 131 */ 132 133 void 134 Hash_InitTable(Hash_Table *t, int numBuckets) 135 { 136 int i; 137 struct Hash_Entry **hp; 138 139 /* 140 * Round up the size to a power of two. 141 */ 142 if (numBuckets <= 0) 143 i = 16; 144 else { 145 for (i = 2; i < numBuckets; i <<= 1) 146 continue; 147 } 148 t->numEntries = 0; 149 t->size = i; 150 t->mask = i - 1; 151 t->bucketPtr = hp = bmake_malloc(sizeof(*hp) * i); 152 while (--i >= 0) 153 *hp++ = NULL; 154 } 155 156 /* 157 *--------------------------------------------------------- 158 * 159 * Hash_DeleteTable -- 160 * 161 * This routine removes everything from a hash table 162 * and frees up the memory space it occupied (except for 163 * the space in the Hash_Table structure). 164 * 165 * Results: 166 * None. 167 * 168 * Side Effects: 169 * Lots of memory is freed up. 170 * 171 *--------------------------------------------------------- 172 */ 173 174 void 175 Hash_DeleteTable(Hash_Table *t) 176 { 177 struct Hash_Entry **hp, *h, *nexth = NULL; 178 int i; 179 180 for (hp = t->bucketPtr, i = t->size; --i >= 0;) { 181 for (h = *hp++; h != NULL; h = nexth) { 182 nexth = h->next; 183 free(h); 184 } 185 } 186 free(t->bucketPtr); 187 188 /* 189 * Set up the hash table to cause memory faults on any future access 190 * attempts until re-initialization. 191 */ 192 t->bucketPtr = NULL; 193 } 194 195 /* 196 *--------------------------------------------------------- 197 * 198 * Hash_FindEntry -- 199 * 200 * Searches a hash table for an entry corresponding to key. 201 * 202 * Input: 203 * t Hash table to search. 204 * key A hash key. 205 * 206 * Results: 207 * The return value is a pointer to the entry for key, 208 * if key was present in the table. If key was not 209 * present, NULL is returned. 210 * 211 * Side Effects: 212 * None. 213 * 214 *--------------------------------------------------------- 215 */ 216 217 Hash_Entry * 218 Hash_FindEntry(Hash_Table *t, const char *key) 219 { 220 Hash_Entry *e; 221 unsigned h; 222 const char *p; 223 224 if (t == NULL || t->bucketPtr == NULL) { 225 return NULL; 226 } 227 for (h = 0, p = key; *p;) 228 h = (h << 5) - h + *p++; 229 p = key; 230 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) 231 if (e->namehash == h && strcmp(e->name, p) == 0) 232 return (e); 233 return NULL; 234 } 235 236 /* 237 *--------------------------------------------------------- 238 * 239 * Hash_CreateEntry -- 240 * 241 * Searches a hash table for an entry corresponding to 242 * key. If no entry is found, then one is created. 243 * 244 * Input: 245 * t Hash table to search. 246 * key A hash key. 247 * newPtr Filled in with TRUE if new entry created, 248 * FALSE otherwise. 249 * 250 * Results: 251 * The return value is a pointer to the entry. If *newPtr 252 * isn't NULL, then *newPtr is filled in with TRUE if a 253 * new entry was created, and FALSE if an entry already existed 254 * with the given key. 255 * 256 * Side Effects: 257 * Memory may be allocated, and the hash buckets may be modified. 258 *--------------------------------------------------------- 259 */ 260 261 Hash_Entry * 262 Hash_CreateEntry(Hash_Table *t, const char *key, Boolean *newPtr) 263 { 264 Hash_Entry *e; 265 unsigned h; 266 const char *p; 267 int keylen; 268 struct Hash_Entry **hp; 269 270 /* 271 * Hash the key. As a side effect, save the length (strlen) of the 272 * key in case we need to create the entry. 273 */ 274 for (h = 0, p = key; *p;) 275 h = (h << 5) - h + *p++; 276 keylen = p - key; 277 p = key; 278 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) { 279 if (e->namehash == h && strcmp(e->name, p) == 0) { 280 if (newPtr != NULL) 281 *newPtr = FALSE; 282 return (e); 283 } 284 } 285 286 /* 287 * The desired entry isn't there. Before allocating a new entry, 288 * expand the table if necessary (and this changes the resulting 289 * bucket chain). 290 */ 291 if (t->numEntries >= rebuildLimit * t->size) 292 RebuildTable(t); 293 e = bmake_malloc(sizeof(*e) + keylen); 294 hp = &t->bucketPtr[h & t->mask]; 295 e->next = *hp; 296 *hp = e; 297 Hash_SetValue(e, NULL); 298 e->namehash = h; 299 (void)strcpy(e->name, p); 300 t->numEntries++; 301 302 if (newPtr != NULL) 303 *newPtr = TRUE; 304 return (e); 305 } 306 307 /* 308 *--------------------------------------------------------- 309 * 310 * Hash_DeleteEntry -- 311 * 312 * Delete the given hash table entry and free memory associated with 313 * it. 314 * 315 * Results: 316 * None. 317 * 318 * Side Effects: 319 * Hash chain that entry lives in is modified and memory is freed. 320 * 321 *--------------------------------------------------------- 322 */ 323 324 void 325 Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e) 326 { 327 Hash_Entry **hp, *p; 328 329 if (e == NULL) 330 return; 331 for (hp = &t->bucketPtr[e->namehash & t->mask]; 332 (p = *hp) != NULL; hp = &p->next) { 333 if (p == e) { 334 *hp = p->next; 335 free(p); 336 t->numEntries--; 337 return; 338 } 339 } 340 (void)write(2, "bad call to Hash_DeleteEntry\n", 29); 341 abort(); 342 } 343 344 /* 345 *--------------------------------------------------------- 346 * 347 * Hash_EnumFirst -- 348 * This procedure sets things up for a complete search 349 * of all entries recorded in the hash table. 350 * 351 * Input: 352 * t Table to be searched. 353 * searchPtr Area in which to keep state about search. 354 * 355 * Results: 356 * The return value is the address of the first entry in 357 * the hash table, or NULL if the table is empty. 358 * 359 * Side Effects: 360 * The information in searchPtr is initialized so that successive 361 * calls to Hash_Next will return successive HashEntry's 362 * from the table. 363 * 364 *--------------------------------------------------------- 365 */ 366 367 Hash_Entry * 368 Hash_EnumFirst(Hash_Table *t, Hash_Search *searchPtr) 369 { 370 searchPtr->tablePtr = t; 371 searchPtr->nextIndex = 0; 372 searchPtr->hashEntryPtr = NULL; 373 return Hash_EnumNext(searchPtr); 374 } 375 376 /* 377 *--------------------------------------------------------- 378 * 379 * Hash_EnumNext -- 380 * This procedure returns successive entries in the hash table. 381 * 382 * Input: 383 * searchPtr Area used to keep state about search. 384 * 385 * Results: 386 * The return value is a pointer to the next HashEntry 387 * in the table, or NULL when the end of the table is 388 * reached. 389 * 390 * Side Effects: 391 * The information in searchPtr is modified to advance to the 392 * next entry. 393 * 394 *--------------------------------------------------------- 395 */ 396 397 Hash_Entry * 398 Hash_EnumNext(Hash_Search *searchPtr) 399 { 400 Hash_Entry *e; 401 Hash_Table *t = searchPtr->tablePtr; 402 403 /* 404 * The hashEntryPtr field points to the most recently returned 405 * entry, or is nil if we are starting up. If not nil, we have 406 * to start at the next one in the chain. 407 */ 408 e = searchPtr->hashEntryPtr; 409 if (e != NULL) 410 e = e->next; 411 /* 412 * If the chain ran out, or if we are starting up, we need to 413 * find the next nonempty chain. 414 */ 415 while (e == NULL) { 416 if (searchPtr->nextIndex >= t->size) 417 return NULL; 418 e = t->bucketPtr[searchPtr->nextIndex++]; 419 } 420 searchPtr->hashEntryPtr = e; 421 return (e); 422 } 423 424 /* 425 *--------------------------------------------------------- 426 * 427 * RebuildTable -- 428 * This local routine makes a new hash table that 429 * is larger than the old one. 430 * 431 * Results: 432 * None. 433 * 434 * Side Effects: 435 * The entire hash table is moved, so any bucket numbers 436 * from the old table are invalid. 437 * 438 *--------------------------------------------------------- 439 */ 440 441 static void 442 RebuildTable(Hash_Table *t) 443 { 444 Hash_Entry *e, *next = NULL, **hp, **xp; 445 int i, mask; 446 Hash_Entry **oldhp; 447 int oldsize; 448 449 oldhp = t->bucketPtr; 450 oldsize = i = t->size; 451 i <<= 1; 452 t->size = i; 453 t->mask = mask = i - 1; 454 t->bucketPtr = hp = bmake_malloc(sizeof(*hp) * i); 455 while (--i >= 0) 456 *hp++ = NULL; 457 for (hp = oldhp, i = oldsize; --i >= 0;) { 458 for (e = *hp++; e != NULL; e = next) { 459 next = e->next; 460 xp = &t->bucketPtr[e->namehash & mask]; 461 e->next = *xp; 462 *xp = e; 463 } 464 } 465 free(oldhp); 466 } 467