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 * Results: 83 * None. 84 * 85 * Side Effects: 86 * Memory is allocated for the initial bucket area. 87 * 88 *--------------------------------------------------------- 89 */ 90 91 /* 92 * Hash_Table *t; Structure to use to hold table. 93 * int numBuckets; How many buckets to create for starters. 94 * This number is rounded up to a power of 95 * two. If <= 0, a reasonable default is 96 * chosen. The table will grow in size later 97 * as needed. 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 * Results: 169 * The return value is a pointer to the entry for key, 170 * if key was present in the table. If key was not 171 * present, NULL is returned. 172 * 173 * Side Effects: 174 * None. 175 * 176 *--------------------------------------------------------- 177 */ 178 179 Hash_Entry * 180 Hash_FindEntry(Hash_Table *t, char *key) 181 { 182 Hash_Entry *e; 183 unsigned h; 184 char *p; 185 186 for (h = 0, p = key; *p;) 187 h = (h << 5) - h + *p++; 188 p = key; 189 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) 190 if (e->namehash == h && strcmp(e->name, p) == 0) 191 return (e); 192 return (NULL); 193 } 194 195 /* 196 *--------------------------------------------------------- 197 * 198 * Hash_CreateEntry -- 199 * 200 * Searches a hash table for an entry corresponding to 201 * key. If no entry is found, then one is created. 202 * 203 * Results: 204 * The return value is a pointer to the entry. If *newPtr 205 * isn't NULL, then *newPtr is filled in with TRUE if a 206 * new entry was created, and FALSE if an entry already existed 207 * with the given key. 208 * 209 * Side Effects: 210 * Memory may be allocated, and the hash buckets may be modified. 211 *--------------------------------------------------------- 212 */ 213 214 Hash_Entry * 215 Hash_CreateEntry(Hash_Table *t, char *key, Boolean *newPtr) 216 { 217 Hash_Entry *e; 218 unsigned h; 219 char *p; 220 int keylen; 221 struct Hash_Entry **hp; 222 223 /* 224 * Hash the key. As a side effect, save the length (strlen) of the 225 * key in case we need to create the entry. 226 */ 227 for (h = 0, p = key; *p;) 228 h = (h << 5) - h + *p++; 229 keylen = p - key; 230 p = key; 231 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) { 232 if (e->namehash == h && strcmp(e->name, p) == 0) { 233 if (newPtr != NULL) 234 *newPtr = FALSE; 235 return (e); 236 } 237 } 238 239 /* 240 * The desired entry isn't there. Before allocating a new entry, 241 * expand the table if necessary (and this changes the resulting 242 * bucket chain). 243 */ 244 if (t->numEntries >= rebuildLimit * t->size) 245 RebuildTable(t); 246 e = (Hash_Entry *) emalloc(sizeof(*e) + keylen); 247 hp = &t->bucketPtr[h & t->mask]; 248 e->next = *hp; 249 *hp = e; 250 e->clientData = NULL; 251 e->namehash = h; 252 strcpy(e->name, p); 253 t->numEntries++; 254 255 if (newPtr != NULL) 256 *newPtr = TRUE; 257 return (e); 258 } 259 260 /* 261 *--------------------------------------------------------- 262 * 263 * Hash_DeleteEntry -- 264 * 265 * Delete the given hash table entry and free memory associated with 266 * it. 267 * 268 * Results: 269 * None. 270 * 271 * Side Effects: 272 * Hash chain that entry lives in is modified and memory is freed. 273 * 274 *--------------------------------------------------------- 275 */ 276 277 void 278 Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e) 279 { 280 Hash_Entry **hp, *p; 281 282 if (e == NULL) 283 return; 284 for (hp = &t->bucketPtr[e->namehash & t->mask]; 285 (p = *hp) != NULL; hp = &p->next) { 286 if (p == e) { 287 *hp = p->next; 288 free((char *)p); 289 t->numEntries--; 290 return; 291 } 292 } 293 write(2, "bad call to Hash_DeleteEntry\n", 29); 294 abort(); 295 } 296 297 /* 298 *--------------------------------------------------------- 299 * 300 * Hash_EnumFirst -- 301 * This procedure sets things up for a complete search 302 * of all entries recorded in the hash table. 303 * 304 * Results: 305 * The return value is the address of the first entry in 306 * the hash table, or NULL if the table is empty. 307 * 308 * Side Effects: 309 * The information in searchPtr is initialized so that successive 310 * calls to Hash_Next will return successive HashEntry's 311 * from the table. 312 * 313 *--------------------------------------------------------- 314 */ 315 316 Hash_Entry * 317 Hash_EnumFirst(Hash_Table *t, Hash_Search *searchPtr) 318 { 319 searchPtr->tablePtr = t; 320 searchPtr->nextIndex = 0; 321 searchPtr->hashEntryPtr = NULL; 322 return Hash_EnumNext(searchPtr); 323 } 324 325 /* 326 *--------------------------------------------------------- 327 * 328 * Hash_EnumNext -- 329 * This procedure returns successive entries in the hash table. 330 * 331 * Results: 332 * The return value is a pointer to the next HashEntry 333 * in the table, or NULL when the end of the table is 334 * reached. 335 * 336 * Side Effects: 337 * The information in searchPtr is modified to advance to the 338 * next entry. 339 * 340 *--------------------------------------------------------- 341 */ 342 343 Hash_Entry * 344 Hash_EnumNext(Hash_Search *searchPtr) 345 { 346 Hash_Entry *e; 347 Hash_Table *t = searchPtr->tablePtr; 348 349 /* 350 * The hashEntryPtr field points to the most recently returned 351 * entry, or is nil if we are starting up. If not nil, we have 352 * to start at the next one in the chain. 353 */ 354 e = searchPtr->hashEntryPtr; 355 if (e != NULL) 356 e = e->next; 357 /* 358 * If the chain ran out, or if we are starting up, we need to 359 * find the next nonempty chain. 360 */ 361 while (e == NULL) { 362 if (searchPtr->nextIndex >= t->size) 363 return (NULL); 364 e = t->bucketPtr[searchPtr->nextIndex++]; 365 } 366 searchPtr->hashEntryPtr = e; 367 return (e); 368 } 369 370 /* 371 *--------------------------------------------------------- 372 * 373 * RebuildTable -- 374 * This local routine makes a new hash table that 375 * is larger than the old one. 376 * 377 * Results: 378 * None. 379 * 380 * Side Effects: 381 * The entire hash table is moved, so any bucket numbers 382 * from the old table are invalid. 383 * 384 *--------------------------------------------------------- 385 */ 386 387 static void 388 RebuildTable(Hash_Table *t) 389 { 390 Hash_Entry *e, *next = NULL, **hp, **xp; 391 int i, mask; 392 Hash_Entry **oldhp; 393 int oldsize; 394 395 oldhp = t->bucketPtr; 396 oldsize = i = t->size; 397 i <<= 1; 398 t->size = i; 399 t->mask = mask = i - 1; 400 t->bucketPtr = hp = (struct Hash_Entry **) emalloc(sizeof(*hp) * i); 401 while (--i >= 0) 402 *hp++ = NULL; 403 for (hp = oldhp, i = oldsize; --i >= 0;) { 404 for (e = *hp++; e != NULL; e = next) { 405 next = e->next; 406 xp = &t->bucketPtr[e->namehash & mask]; 407 e->next = *xp; 408 *xp = e; 409 } 410 } 411 free((char *)oldhp); 412 } 413