1 /* 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 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. 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. 25 * 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 36 * SUCH DAMAGE. 37 * 38 * $NetBSD: hash.c,v 1.1.1.1 1999/11/19 04:30:56 mrg Exp $ 39 */ 40 41 #include <sys/types.h> 42 43 #include <stdlib.h> 44 #include <string.h> 45 #include <unistd.h> 46 #include <libutil.h> 47 48 /* hash.c -- 49 * 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. 54 */ 55 #include "sprite.h" 56 #ifndef ORDER 57 #include "make.h" 58 #endif /* ORDER */ 59 #include "hash.h" 60 61 /* 62 * Forward references to local procedures that are used before they're 63 * defined: 64 */ 65 66 static void RebuildTable(Hash_Table *); 67 68 /* 69 * The following defines the ratio of # entries to # buckets 70 * at which we rebuild the table to make it larger. 71 */ 72 73 #define rebuildLimit 8 74 75 /* 76 *--------------------------------------------------------- 77 * 78 * Hash_InitTable -- 79 * 80 * This routine just sets up the hash table. 81 * 82 * Arguments: 83 * Hash_Table *t 84 * Structure to use to hold table. 85 * int numBuckets 86 * How many buckets to create for starters. This number is 87 * rounded up to a power of 2. If <= 0, a reasonable default 88 * is chosen. The table will grow in size later as needed. 89 * 90 * Results: 91 * None. 92 * 93 * Side Effects: 94 * Memory is allocated for the initial bucket area. 95 * 96 *--------------------------------------------------------- 97 */ 98 99 void 100 Hash_InitTable(Hash_Table *t, int numBuckets) 101 { 102 int i; 103 struct Hash_Entry **hp; 104 105 /* 106 * Round up the size to a power of two. 107 */ 108 if (numBuckets <= 0) 109 i = 16; 110 else { 111 for (i = 2; i < numBuckets; i <<= 1) 112 continue; 113 } 114 t->numEntries = 0; 115 t->size = i; 116 t->mask = i - 1; 117 t->bucketPtr = hp = (struct Hash_Entry **)emalloc(sizeof(*hp) * i); 118 while (--i >= 0) 119 *hp++ = NULL; 120 } 121 122 /* 123 *--------------------------------------------------------- 124 * 125 * Hash_DeleteTable -- 126 * 127 * This routine removes everything from a hash table 128 * and frees up the memory space it occupied (except for 129 * the space in the Hash_Table structure). 130 * 131 * Results: 132 * None. 133 * 134 * Side Effects: 135 * Lots of memory is freed up. 136 * 137 *--------------------------------------------------------- 138 */ 139 140 void 141 Hash_DeleteTable(Hash_Table *t) 142 { 143 struct Hash_Entry **hp, *h, *nexth = NULL; 144 int i; 145 146 for (hp = t->bucketPtr, i = t->size; --i >= 0;) { 147 for (h = *hp++; h != NULL; h = nexth) { 148 nexth = h->next; 149 free((char *)h); 150 } 151 } 152 free((char *)t->bucketPtr); 153 154 /* 155 * Set up the hash table to cause memory faults on any future access 156 * attempts until re-initialization. 157 */ 158 t->bucketPtr = NULL; 159 } 160 161 /* 162 *--------------------------------------------------------- 163 * 164 * Hash_FindEntry -- 165 * 166 * Searches a hash table for an entry corresponding to key. 167 * 168 * Arguments: 169 * Hash_Table *t 170 * Hash table to be searched. 171 * char *key 172 * A hash key. 173 * 174 * Results: 175 * The return value is a pointer to the entry for key, 176 * if key was present in the table. If key was not 177 * present, NULL is returned. 178 * 179 * Side Effects: 180 * None. 181 * 182 *--------------------------------------------------------- 183 */ 184 185 Hash_Entry * 186 Hash_FindEntry(Hash_Table *t, char *key) 187 { 188 Hash_Entry *e; 189 unsigned h; 190 char *p; 191 192 for (h = 0, p = key; *p;) 193 h = (h << 5) - h + *p++; 194 p = key; 195 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) 196 if (e->namehash == h && strcmp(e->name, p) == 0) 197 return (e); 198 return (NULL); 199 } 200 201 /* 202 *--------------------------------------------------------- 203 * 204 * Hash_CreateEntry -- 205 * 206 * Searches a hash table for an entry corresponding to 207 * key. If no entry is found, then one is created. 208 * 209 * Arguments: 210 * Hash_Table *t 211 * Hash table to be searched. 212 * char *key 213 * A hash key. 214 * Boolean *newPtr 215 * Filled in with TRUE if new entry created, FALSE otherwise. 216 * 217 * Results: 218 * The return value is a pointer to the entry. If *newPtr 219 * isn't NULL, then *newPtr is filled in with TRUE if a 220 * new entry was created, and FALSE if an entry already existed 221 * with the given key. 222 * 223 * Side Effects: 224 * Memory may be allocated, and the hash buckets may be modified. 225 *--------------------------------------------------------- 226 */ 227 228 Hash_Entry * 229 Hash_CreateEntry(Hash_Table *t, char *key, Boolean *newPtr) 230 { 231 Hash_Entry *e; 232 unsigned h; 233 char *p; 234 int keylen; 235 struct Hash_Entry **hp; 236 237 /* 238 * Hash the key. As a side effect, save the length (strlen) of the 239 * key in case we need to create the entry. 240 */ 241 for (h = 0, p = key; *p;) 242 h = (h << 5) - h + *p++; 243 keylen = p - key; 244 p = key; 245 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) { 246 if (e->namehash == h && strcmp(e->name, p) == 0) { 247 if (newPtr != NULL) 248 *newPtr = FALSE; 249 return (e); 250 } 251 } 252 253 /* 254 * The desired entry isn't there. Before allocating a new entry, 255 * expand the table if necessary (and this changes the resulting 256 * bucket chain). 257 */ 258 if (t->numEntries >= rebuildLimit * t->size) 259 RebuildTable(t); 260 e = (Hash_Entry *) emalloc(sizeof(*e) + keylen); 261 hp = &t->bucketPtr[h & t->mask]; 262 e->next = *hp; 263 *hp = e; 264 e->clientData = NULL; 265 e->namehash = h; 266 strcpy(e->name, p); 267 t->numEntries++; 268 269 if (newPtr != NULL) 270 *newPtr = TRUE; 271 return (e); 272 } 273 274 /* 275 *--------------------------------------------------------- 276 * 277 * Hash_DeleteEntry -- 278 * 279 * Delete the given hash table entry and free memory associated with it. 280 * 281 * Results: 282 * None. 283 * 284 * Side Effects: 285 * Hash chain that entry lives in is modified and memory is freed. 286 * 287 *--------------------------------------------------------- 288 */ 289 290 void 291 Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e) 292 { 293 Hash_Entry **hp, *p; 294 295 if (e == NULL) 296 return; 297 for (hp = &t->bucketPtr[e->namehash & t->mask]; 298 (p = *hp) != NULL; hp = &p->next) { 299 if (p == e) { 300 *hp = p->next; 301 free((char *)p); 302 t->numEntries--; 303 return; 304 } 305 } 306 write(2, "bad call to Hash_DeleteEntry\n", 29); 307 abort(); 308 } 309 310 /* 311 *--------------------------------------------------------- 312 * 313 * Hash_EnumFirst -- 314 * This procedure sets things up for a complete search 315 * of all entries recorded in the hash table. 316 * 317 * Arguments: 318 * Hash_Table *t 319 * Hash table to be searched. 320 * Hash_Search *searchPtr 321 * Area in which to keep state about search. 322 * 323 * Results: 324 * The return value is the address of the first entry in 325 * the hash table, or NULL if the table is empty. 326 * 327 * Side Effects: 328 * The information in searchPtr is initialized so that successive 329 * calls to Hash_Next will return successive HashEntry's 330 * from the table. 331 * 332 *--------------------------------------------------------- 333 */ 334 335 Hash_Entry * 336 Hash_EnumFirst(Hash_Table *t, Hash_Search *searchPtr) 337 { 338 searchPtr->tablePtr = t; 339 searchPtr->nextIndex = 0; 340 searchPtr->hashEntryPtr = NULL; 341 return Hash_EnumNext(searchPtr); 342 } 343 344 /* 345 *--------------------------------------------------------- 346 * 347 * Hash_EnumNext -- 348 * This procedure returns successive entries in the hash table. 349 * 350 * Arguments: 351 * Hash_Search *searchPtr 352 * Area in which to keep state about search. 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(Hash_Search *searchPtr) 368 { 369 Hash_Entry *e; 370 Hash_Table *t = searchPtr->tablePtr; 371 372 /* 373 * The hashEntryPtr field points to the most recently returned 374 * entry, or is nil if we are starting up. If not nil, we have 375 * to start at the next one in the chain. 376 */ 377 e = searchPtr->hashEntryPtr; 378 if (e != NULL) 379 e = e->next; 380 /* 381 * If the chain ran out, or if we are starting up, we need to 382 * find the next nonempty chain. 383 */ 384 while (e == NULL) { 385 if (searchPtr->nextIndex >= t->size) 386 return (NULL); 387 e = t->bucketPtr[searchPtr->nextIndex++]; 388 } 389 searchPtr->hashEntryPtr = e; 390 return (e); 391 } 392 393 /* 394 *--------------------------------------------------------- 395 * 396 * RebuildTable -- 397 * This local routine makes a new hash table that 398 * is larger than the old one. 399 * 400 * Results: 401 * None. 402 * 403 * Side Effects: 404 * The entire hash table is moved, so any bucket numbers 405 * from the old table are invalid. 406 * 407 *--------------------------------------------------------- 408 */ 409 410 static void 411 RebuildTable(Hash_Table *t) 412 { 413 Hash_Entry *e, *next = NULL, **hp, **xp; 414 int i, mask; 415 Hash_Entry **oldhp; 416 int oldsize; 417 418 oldhp = t->bucketPtr; 419 oldsize = i = t->size; 420 i <<= 1; 421 t->size = i; 422 t->mask = mask = i - 1; 423 t->bucketPtr = hp = (struct Hash_Entry **) emalloc(sizeof(*hp) * i); 424 while (--i >= 0) 425 *hp++ = NULL; 426 for (hp = oldhp, i = oldsize; --i >= 0;) { 427 for (e = *hp++; e != NULL; e = next) { 428 next = e->next; 429 xp = &t->bucketPtr[e->namehash & mask]; 430 e->next = *xp; 431 *xp = e; 432 } 433 } 434 free((char *)oldhp); 435 } 436