1 /* $FreeBSD$ */ 2 /* $NetBSD: hash.c,v 1.1.1.1 1999/11/19 04:30:56 mrg Exp $ */ 3 4 /* 5 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California. 6 * Copyright (c) 1988, 1989 by Adam de Boor 7 * Copyright (c) 1989 by Berkeley Softworks 8 * All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * Adam de Boor. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 */ 41 42 #ifdef MAKE_BOOTSTRAP 43 static char rcsid[] = "$NetBSD: hash.c,v 1.1.1.1 1999/11/19 04:30:56 mrg Exp $"; 44 #else 45 #include <sys/cdefs.h> 46 #ifndef lint 47 #if 0 48 static char sccsid[] = "@(#)hash.c 8.1 (Berkeley) 6/6/93"; 49 #else 50 __RCSID("$NetBSD: hash.c,v 1.1.1.1 1999/11/19 04:30:56 mrg Exp $"); 51 #endif 52 #endif /* not lint */ 53 #endif 54 55 #include <sys/types.h> 56 57 #include <stdlib.h> 58 #include <string.h> 59 #include <unistd.h> 60 61 /* hash.c -- 62 * 63 * This module contains routines to manipulate a hash table. 64 * See hash.h for a definition of the structure of the hash 65 * table. Hash tables grow automatically as the amount of 66 * information increases. 67 */ 68 #include "sprite.h" 69 #ifndef ORDER 70 #include "make.h" 71 #endif /* ORDER */ 72 #include "hash.h" 73 #include "ealloc.h" 74 75 /* 76 * Forward references to local procedures that are used before they're 77 * defined: 78 */ 79 80 static void RebuildTable(Hash_Table *); 81 82 /* 83 * The following defines the ratio of # entries to # buckets 84 * at which we rebuild the table to make it larger. 85 */ 86 87 #define rebuildLimit 8 88 89 /* 90 *--------------------------------------------------------- 91 * 92 * Hash_InitTable -- 93 * 94 * This routine just sets up the hash table. 95 * 96 * Results: 97 * None. 98 * 99 * Side Effects: 100 * Memory is allocated for the initial bucket area. 101 * 102 *--------------------------------------------------------- 103 */ 104 105 void 106 Hash_InitTable( 107 register Hash_Table *t, /* Structure to use to hold table. */ 108 int numBuckets) /* How many buckets to create for starters. 109 * This number is rounded up to a power of 110 * two. If <= 0, a reasonable default is 111 * chosen. The table will grow in size later 112 * as needed. */ 113 { 114 register int i; 115 register struct Hash_Entry **hp; 116 117 /* 118 * Round up the size to a power of two. 119 */ 120 if (numBuckets <= 0) 121 i = 16; 122 else { 123 for (i = 2; i < numBuckets; i <<= 1) 124 continue; 125 } 126 t->numEntries = 0; 127 t->size = i; 128 t->mask = i - 1; 129 t->bucketPtr = hp = (struct Hash_Entry **)emalloc(sizeof(*hp) * i); 130 while (--i >= 0) 131 *hp++ = NULL; 132 } 133 134 /* 135 *--------------------------------------------------------- 136 * 137 * Hash_DeleteTable -- 138 * 139 * This routine removes everything from a hash table 140 * and frees up the memory space it occupied (except for 141 * the space in the Hash_Table structure). 142 * 143 * Results: 144 * None. 145 * 146 * Side Effects: 147 * Lots of memory is freed up. 148 * 149 *--------------------------------------------------------- 150 */ 151 152 void 153 Hash_DeleteTable(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( 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( 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(Hash_Table *t, Hash_Entry *e) 297 { 298 register Hash_Entry **hp, *p; 299 300 if (e == NULL) 301 return; 302 for (hp = &t->bucketPtr[e->namehash & t->mask]; 303 (p = *hp) != NULL; hp = &p->next) { 304 if (p == e) { 305 *hp = p->next; 306 free((char *)p); 307 t->numEntries--; 308 return; 309 } 310 } 311 (void)write(2, "bad call to Hash_DeleteEntry\n", 29); 312 abort(); 313 } 314 315 /* 316 *--------------------------------------------------------- 317 * 318 * Hash_EnumFirst -- 319 * This procedure sets things up for a complete search 320 * of all entries recorded in the hash table. 321 * 322 * Results: 323 * The return value is the address of the first entry in 324 * the hash table, or NULL if the table is empty. 325 * 326 * Side Effects: 327 * The information in searchPtr is initialized so that successive 328 * calls to Hash_Next will return successive HashEntry's 329 * from the table. 330 * 331 *--------------------------------------------------------- 332 */ 333 334 Hash_Entry * 335 Hash_EnumFirst( 336 Hash_Table *t, /* Table to be searched. */ 337 register Hash_Search *searchPtr)/* Area in which to keep state 338 * about search.*/ 339 { 340 searchPtr->tablePtr = t; 341 searchPtr->nextIndex = 0; 342 searchPtr->hashEntryPtr = NULL; 343 return Hash_EnumNext(searchPtr); 344 } 345 346 /* 347 *--------------------------------------------------------- 348 * 349 * Hash_EnumNext -- 350 * This procedure returns successive entries in the hash table. 351 * 352 * Results: 353 * The return value is a pointer to the next HashEntry 354 * in the table, or NULL when the end of the table is 355 * reached. 356 * 357 * Side Effects: 358 * The information in searchPtr is modified to advance to the 359 * next entry. 360 * 361 *--------------------------------------------------------- 362 */ 363 364 Hash_Entry * 365 Hash_EnumNext( 366 register Hash_Search *searchPtr) /* Area used to keep state about 367 search. */ 368 { 369 register 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(register Hash_Table *t) 412 { 413 register Hash_Entry *e, *next = NULL, **hp, **xp; 414 register int i, mask; 415 register 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