1 /* $NetBSD: hash.c,v 1.1 1999/11/23 05:28:20 mrg Exp $ */ 2 3 /* 4 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California. 5 * Copyright (c) 1988, 1989 by Adam de Boor 6 * Copyright (c) 1989 by Berkeley Softworks 7 * All rights reserved. 8 * 9 * This code is derived from software contributed to Berkeley by 10 * Adam de Boor. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 */ 40 41 #ifdef MAKE_BOOTSTRAP 42 static char rcsid[] = "$NetBSD: hash.c,v 1.1 1999/11/23 05:28:20 mrg Exp $"; 43 #else 44 #include <sys/cdefs.h> 45 #ifndef lint 46 #if 0 47 static char sccsid[] = "@(#)hash.c 8.1 (Berkeley) 6/6/93"; 48 #else 49 __RCSID("$NetBSD: hash.c,v 1.1 1999/11/23 05:28:20 mrg Exp $"); 50 #endif 51 #endif /* not lint */ 52 #endif 53 54 #include <sys/types.h> 55 56 #include <stdlib.h> 57 #include <string.h> 58 #include <unistd.h> 59 60 /* hash.c -- 61 * 62 * This module contains routines to manipulate a hash table. 63 * See hash.h for a definition of the structure of the hash 64 * table. Hash tables grow automatically as the amount of 65 * information increases. 66 */ 67 #include "sprite.h" 68 #ifndef ORDER 69 #include "make.h" 70 #endif /* ORDER */ 71 #include "hash.h" 72 #include "ealloc.h" 73 74 /* 75 * Forward references to local procedures that are used before they're 76 * defined: 77 */ 78 79 static void RebuildTable __P((Hash_Table *)); 80 81 /* 82 * The following defines the ratio of # entries to # buckets 83 * at which we rebuild the table to make it larger. 84 */ 85 86 #define rebuildLimit 8 87 88 /* 89 *--------------------------------------------------------- 90 * 91 * Hash_InitTable -- 92 * 93 * This routine just sets up the hash table. 94 * 95 * Results: 96 * None. 97 * 98 * Side Effects: 99 * Memory is allocated for the initial bucket area. 100 * 101 *--------------------------------------------------------- 102 */ 103 104 void 105 Hash_InitTable(t, numBuckets) 106 register Hash_Table *t; /* Structure to use to hold table. */ 107 int numBuckets; /* How many buckets to create for starters. 108 * This number is rounded up to a power of 109 * two. If <= 0, a reasonable default is 110 * chosen. The table will grow in size later 111 * as needed. */ 112 { 113 register int i; 114 register struct Hash_Entry **hp; 115 116 /* 117 * Round up the size to a power of two. 118 */ 119 if (numBuckets <= 0) 120 i = 16; 121 else { 122 for (i = 2; i < numBuckets; i <<= 1) 123 continue; 124 } 125 t->numEntries = 0; 126 t->size = i; 127 t->mask = i - 1; 128 t->bucketPtr = hp = (struct Hash_Entry **)emalloc(sizeof(*hp) * i); 129 while (--i >= 0) 130 *hp++ = NULL; 131 } 132 133 /* 134 *--------------------------------------------------------- 135 * 136 * Hash_DeleteTable -- 137 * 138 * This routine removes everything from a hash table 139 * and frees up the memory space it occupied (except for 140 * the space in the Hash_Table structure). 141 * 142 * Results: 143 * None. 144 * 145 * Side Effects: 146 * Lots of memory is freed up. 147 * 148 *--------------------------------------------------------- 149 */ 150 151 void 152 Hash_DeleteTable(t) 153 Hash_Table *t; 154 { 155 register struct Hash_Entry **hp, *h, *nexth = NULL; 156 register int i; 157 158 for (hp = t->bucketPtr, i = t->size; --i >= 0;) { 159 for (h = *hp++; h != NULL; h = nexth) { 160 nexth = h->next; 161 free((char *)h); 162 } 163 } 164 free((char *)t->bucketPtr); 165 166 /* 167 * Set up the hash table to cause memory faults on any future access 168 * attempts until re-initialization. 169 */ 170 t->bucketPtr = NULL; 171 } 172 173 /* 174 *--------------------------------------------------------- 175 * 176 * Hash_FindEntry -- 177 * 178 * Searches a hash table for an entry corresponding to key. 179 * 180 * Results: 181 * The return value is a pointer to the entry for key, 182 * if key was present in the table. If key was not 183 * present, NULL is returned. 184 * 185 * Side Effects: 186 * None. 187 * 188 *--------------------------------------------------------- 189 */ 190 191 Hash_Entry * 192 Hash_FindEntry(t, key) 193 Hash_Table *t; /* Hash table to search. */ 194 char *key; /* A hash key. */ 195 { 196 register Hash_Entry *e; 197 register unsigned h; 198 register char *p; 199 200 for (h = 0, p = key; *p;) 201 h = (h << 5) - h + *p++; 202 p = key; 203 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) 204 if (e->namehash == h && strcmp(e->name, p) == 0) 205 return (e); 206 return (NULL); 207 } 208 209 /* 210 *--------------------------------------------------------- 211 * 212 * Hash_CreateEntry -- 213 * 214 * Searches a hash table for an entry corresponding to 215 * key. If no entry is found, then one is created. 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(t, key, newPtr) 230 register Hash_Table *t; /* Hash table to search. */ 231 char *key; /* A hash key. */ 232 Boolean *newPtr; /* Filled in with TRUE if new entry created, 233 * FALSE otherwise. */ 234 { 235 register Hash_Entry *e; 236 register unsigned h; 237 register char *p; 238 int keylen; 239 struct Hash_Entry **hp; 240 241 /* 242 * Hash the key. As a side effect, save the length (strlen) of the 243 * key in case we need to create the entry. 244 */ 245 for (h = 0, p = key; *p;) 246 h = (h << 5) - h + *p++; 247 keylen = p - key; 248 p = key; 249 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) { 250 if (e->namehash == h && strcmp(e->name, p) == 0) { 251 if (newPtr != NULL) 252 *newPtr = FALSE; 253 return (e); 254 } 255 } 256 257 /* 258 * The desired entry isn't there. Before allocating a new entry, 259 * expand the table if necessary (and this changes the resulting 260 * bucket chain). 261 */ 262 if (t->numEntries >= rebuildLimit * t->size) 263 RebuildTable(t); 264 e = (Hash_Entry *) emalloc(sizeof(*e) + keylen); 265 hp = &t->bucketPtr[h & t->mask]; 266 e->next = *hp; 267 *hp = e; 268 e->clientData = NULL; 269 e->namehash = h; 270 (void) strcpy(e->name, p); 271 t->numEntries++; 272 273 if (newPtr != NULL) 274 *newPtr = TRUE; 275 return (e); 276 } 277 278 /* 279 *--------------------------------------------------------- 280 * 281 * Hash_DeleteEntry -- 282 * 283 * Delete the given hash table entry and free memory associated with 284 * it. 285 * 286 * Results: 287 * None. 288 * 289 * Side Effects: 290 * Hash chain that entry lives in is modified and memory is freed. 291 * 292 *--------------------------------------------------------- 293 */ 294 295 void 296 Hash_DeleteEntry(t, e) 297 Hash_Table *t; 298 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(t, searchPtr) 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(searchPtr) 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(t) 414 register Hash_Table *t; 415 { 416 register Hash_Entry *e, *next = NULL, **hp, **xp; 417 register int i, mask; 418 register Hash_Entry **oldhp; 419 int oldsize; 420 421 oldhp = t->bucketPtr; 422 oldsize = i = t->size; 423 i <<= 1; 424 t->size = i; 425 t->mask = mask = i - 1; 426 t->bucketPtr = hp = (struct Hash_Entry **) emalloc(sizeof(*hp) * i); 427 while (--i >= 0) 428 *hp++ = NULL; 429 for (hp = oldhp, i = oldsize; --i >= 0;) { 430 for (e = *hp++; e != NULL; e = next) { 431 next = e->next; 432 xp = &t->bucketPtr[e->namehash & mask]; 433 e->next = *xp; 434 *xp = e; 435 } 436 } 437 free((char *)oldhp); 438 } 439