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 for (h = 0, p = key; *p;) 225 h = (h << 5) - h + *p++; 226 p = key; 227 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) 228 if (e->namehash == h && strcmp(e->name, p) == 0) 229 return (e); 230 return NULL; 231 } 232 233 /* 234 *--------------------------------------------------------- 235 * 236 * Hash_CreateEntry -- 237 * 238 * Searches a hash table for an entry corresponding to 239 * key. If no entry is found, then one is created. 240 * 241 * Input: 242 * t Hash table to search. 243 * key A hash key. 244 * newPtr Filled in with TRUE if new entry created, 245 * FALSE otherwise. 246 * 247 * Results: 248 * The return value is a pointer to the entry. If *newPtr 249 * isn't NULL, then *newPtr is filled in with TRUE if a 250 * new entry was created, and FALSE if an entry already existed 251 * with the given key. 252 * 253 * Side Effects: 254 * Memory may be allocated, and the hash buckets may be modified. 255 *--------------------------------------------------------- 256 */ 257 258 Hash_Entry * 259 Hash_CreateEntry(Hash_Table *t, const char *key, Boolean *newPtr) 260 { 261 Hash_Entry *e; 262 unsigned h; 263 const char *p; 264 int keylen; 265 struct Hash_Entry **hp; 266 267 /* 268 * Hash the key. As a side effect, save the length (strlen) of the 269 * key in case we need to create the entry. 270 */ 271 for (h = 0, p = key; *p;) 272 h = (h << 5) - h + *p++; 273 keylen = p - key; 274 p = key; 275 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) { 276 if (e->namehash == h && strcmp(e->name, p) == 0) { 277 if (newPtr != NULL) 278 *newPtr = FALSE; 279 return (e); 280 } 281 } 282 283 /* 284 * The desired entry isn't there. Before allocating a new entry, 285 * expand the table if necessary (and this changes the resulting 286 * bucket chain). 287 */ 288 if (t->numEntries >= rebuildLimit * t->size) 289 RebuildTable(t); 290 e = bmake_malloc(sizeof(*e) + keylen); 291 hp = &t->bucketPtr[h & t->mask]; 292 e->next = *hp; 293 *hp = e; 294 Hash_SetValue(e, NULL); 295 e->namehash = h; 296 (void)strcpy(e->name, p); 297 t->numEntries++; 298 299 if (newPtr != NULL) 300 *newPtr = TRUE; 301 return (e); 302 } 303 304 /* 305 *--------------------------------------------------------- 306 * 307 * Hash_DeleteEntry -- 308 * 309 * Delete the given hash table entry and free memory associated with 310 * it. 311 * 312 * Results: 313 * None. 314 * 315 * Side Effects: 316 * Hash chain that entry lives in is modified and memory is freed. 317 * 318 *--------------------------------------------------------- 319 */ 320 321 void 322 Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e) 323 { 324 Hash_Entry **hp, *p; 325 326 if (e == NULL) 327 return; 328 for (hp = &t->bucketPtr[e->namehash & t->mask]; 329 (p = *hp) != NULL; hp = &p->next) { 330 if (p == e) { 331 *hp = p->next; 332 free(p); 333 t->numEntries--; 334 return; 335 } 336 } 337 (void)write(2, "bad call to Hash_DeleteEntry\n", 29); 338 abort(); 339 } 340 341 /* 342 *--------------------------------------------------------- 343 * 344 * Hash_EnumFirst -- 345 * This procedure sets things up for a complete search 346 * of all entries recorded in the hash table. 347 * 348 * Input: 349 * t Table to be searched. 350 * searchPtr Area in which to keep state about search. 351 * 352 * Results: 353 * The return value is the address of the first entry in 354 * the hash table, or NULL if the table is empty. 355 * 356 * Side Effects: 357 * The information in searchPtr is initialized so that successive 358 * calls to Hash_Next will return successive HashEntry's 359 * from the table. 360 * 361 *--------------------------------------------------------- 362 */ 363 364 Hash_Entry * 365 Hash_EnumFirst(Hash_Table *t, Hash_Search *searchPtr) 366 { 367 searchPtr->tablePtr = t; 368 searchPtr->nextIndex = 0; 369 searchPtr->hashEntryPtr = NULL; 370 return Hash_EnumNext(searchPtr); 371 } 372 373 /* 374 *--------------------------------------------------------- 375 * 376 * Hash_EnumNext -- 377 * This procedure returns successive entries in the hash table. 378 * 379 * Input: 380 * searchPtr Area used to keep state about search. 381 * 382 * Results: 383 * The return value is a pointer to the next HashEntry 384 * in the table, or NULL when the end of the table is 385 * reached. 386 * 387 * Side Effects: 388 * The information in searchPtr is modified to advance to the 389 * next entry. 390 * 391 *--------------------------------------------------------- 392 */ 393 394 Hash_Entry * 395 Hash_EnumNext(Hash_Search *searchPtr) 396 { 397 Hash_Entry *e; 398 Hash_Table *t = searchPtr->tablePtr; 399 400 /* 401 * The hashEntryPtr field points to the most recently returned 402 * entry, or is nil if we are starting up. If not nil, we have 403 * to start at the next one in the chain. 404 */ 405 e = searchPtr->hashEntryPtr; 406 if (e != NULL) 407 e = e->next; 408 /* 409 * If the chain ran out, or if we are starting up, we need to 410 * find the next nonempty chain. 411 */ 412 while (e == NULL) { 413 if (searchPtr->nextIndex >= t->size) 414 return NULL; 415 e = t->bucketPtr[searchPtr->nextIndex++]; 416 } 417 searchPtr->hashEntryPtr = e; 418 return (e); 419 } 420 421 /* 422 *--------------------------------------------------------- 423 * 424 * RebuildTable -- 425 * This local routine makes a new hash table that 426 * is larger than the old one. 427 * 428 * Results: 429 * None. 430 * 431 * Side Effects: 432 * The entire hash table is moved, so any bucket numbers 433 * from the old table are invalid. 434 * 435 *--------------------------------------------------------- 436 */ 437 438 static void 439 RebuildTable(Hash_Table *t) 440 { 441 Hash_Entry *e, *next = NULL, **hp, **xp; 442 int i, mask; 443 Hash_Entry **oldhp; 444 int oldsize; 445 446 oldhp = t->bucketPtr; 447 oldsize = i = t->size; 448 i <<= 1; 449 t->size = i; 450 t->mask = mask = i - 1; 451 t->bucketPtr = hp = bmake_malloc(sizeof(*hp) * i); 452 while (--i >= 0) 453 *hp++ = NULL; 454 for (hp = oldhp, i = oldsize; --i >= 0;) { 455 for (e = *hp++; e != NULL; e = next) { 456 next = e->next; 457 xp = &t->bucketPtr[e->namehash & mask]; 458 e->next = *xp; 459 *xp = e; 460 } 461 } 462 free(oldhp); 463 } 464