Mercurial > ~mikael > mcabber > hg
annotate mcabber/libjabber/genhash.c @ 1346:e36b21e11760
Remove useless casts
| author | Mikael Berthe <mikael@lilotux.net> |
|---|---|
| date | Fri, 09 Nov 2007 20:09:47 +0100 |
| parents | c3ae9251c197 |
| children |
| rev | line source |
|---|---|
| 25 | 1 /* |
| 2 * This program is free software; you can redistribute it and/or modify | |
| 3 * it under the terms of the GNU General Public License as published by | |
| 4 * the Free Software Foundation; either version 2 of the License, or | |
| 5 * (at your option) any later version. | |
| 6 * | |
| 7 * This program is distributed in the hope that it will be useful, | |
| 8 * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 10 * GNU General Public License for more details. | |
| 11 * | |
| 12 * You should have received a copy of the GNU General Public License | |
| 13 * along with this program; if not, write to the Free Software | |
| 14 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
| 15 * | |
|
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16 * Copyrights |
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17 * |
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18 * Portions created by or assigned to Jabber.com, Inc. are |
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19 * Copyright (c) 1999-2002 Jabber.com, Inc. All Rights Reserved. Contact |
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20 * information for Jabber.com, Inc. is available at http://www.jabber.com/. |
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21 * |
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22 * Portions Copyright (c) 1998-1999 Jeremie Miller. |
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23 * |
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24 * Acknowledgements |
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25 * |
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26 * Special thanks to the Jabber Open Source Contributors for their |
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27 * suggestions and support of Jabber. |
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28 * |
| 25 | 29 */ |
| 30 #include <libxode.h> | |
| 31 | |
| 32 /***************************************************************************** | |
| 33 * Internal type definitions | |
| 34 */ | |
| 35 | |
| 36 typedef struct tagHNODE | |
| 37 { | |
| 38 struct tagHNODE *next; /* next node in list */ | |
| 39 const void *key; /* key pointer */ | |
| 40 void *value; /* value pointer */ | |
| 41 } HNODE; | |
| 42 | |
| 43 #define SLAB_NUM_NODES 64 /* allocate this many nodes per slab */ | |
| 44 | |
| 45 typedef struct tagHSLAB | |
| 46 { | |
| 47 struct tagHSLAB *next; /* next slab pointer */ | |
| 48 HNODE nodes[SLAB_NUM_NODES]; /* the actual nodes */ | |
| 49 } HSLAB; | |
| 50 | |
| 51 #define HASH_NUM_BUCKETS 509 /* should be a prime number; see Knuth */ | |
| 52 | |
| 53 typedef struct tagHASHTABLE_INTERNAL | |
| 54 { | |
| 55 unsigned long sig1; /* first signature word */ | |
| 56 KEYHASHFUNC hash; /* hash function */ | |
| 57 KEYCOMPAREFUNC cmp; /* comparison function */ | |
| 58 int count; /* table entry count */ | |
| 59 int bcount; /* bucket count */ | |
| 60 HNODE **buckets; /* the hash buckets */ | |
| 61 unsigned long sig2; /* second signature word */ | |
| 62 | |
| 63 } HASHTABLE_INTERNAL; | |
| 64 | |
| 65 #define HASH_SIG1 0x68736148UL /* "Hash" */ | |
| 66 #define HASH_SIG2 0x6F627245UL /* "Erbo" */ | |
| 67 | |
| 68 #define do_hash(tb,key) ((*((tb)->hash))(key) % ((tb)->bcount)) | |
| 69 | |
| 70 static HNODE *s_free_nodes = NULL; /* free nodes list */ | |
| 71 static HSLAB *s_slabs = NULL; /* node slabs list */ | |
| 72 | |
| 73 /***************************************************************************** | |
| 74 * Internal functions | |
| 75 */ | |
| 76 | |
| 77 static HNODE *allocate_node( | |
| 78 const void *key, /* key pointer for this node */ | |
| 79 void *value) /* value pointer for this node */ | |
| 80 /* | |
| 81 allocate_node allocates a new hash node and fills it. Returns NULL if the | |
| 82 node could not be allocated. | |
| 83 */ | |
| 84 { | |
| 85 HNODE *rc; /* return from this function */ | |
| 86 | |
| 87 if (!s_free_nodes) | |
| 88 { /* allocate a new slabful of nodes and chain them to make a new free list */ | |
| 89 register int i; /* loop counter */ | |
| 90 HSLAB *slab = (HSLAB *)malloc(sizeof(HSLAB)); | |
| 91 if (!slab) | |
| 92 return NULL; | |
| 93 memset(slab,0,sizeof(HSLAB)); | |
| 94 slab->next = s_slabs; | |
| 95 for (i=0; i<(SLAB_NUM_NODES-1); i++) | |
| 96 slab->nodes[i].next = &(slab->nodes[i+1]); | |
| 97 s_free_nodes = &(slab->nodes[0]); | |
| 98 s_slabs = slab; | |
| 99 | |
| 100 } /* end if */ | |
| 101 | |
| 102 /* grab a node off the fron of the free list and fill it */ | |
| 103 rc = s_free_nodes; | |
| 104 s_free_nodes = rc->next; | |
| 105 rc->next = NULL; | |
| 106 rc->key = key; | |
| 107 rc->value = value; | |
| 108 return rc; | |
| 109 | |
| 110 } /* end allocate_node */ | |
| 111 | |
| 112 static void free_node( | |
| 113 HNODE *node) /* node to be freed */ | |
| 114 /* | |
| 115 free_node returns a hash node to the list. | |
| 116 */ | |
| 117 { | |
| 118 /* zap the node contents to avoid problems later */ | |
| 119 memset(node,0,sizeof(HNODE)); | |
| 120 | |
| 121 /* chain it onto the free list */ | |
| 122 node->next = s_free_nodes; | |
| 123 s_free_nodes = node; | |
| 124 | |
| 125 } /* end free_node */ | |
| 126 | |
| 127 static HNODE *find_node( | |
| 128 HASHTABLE_INTERNAL *tab, /* pointer to hash table */ | |
| 129 const void *key, /* key value to look up */ | |
| 130 int bucket) /* bucket number (-1 to have function compute it) */ | |
| 131 /* | |
| 132 find_node walks a hash bucket to find a node whose key matches the named key value. | |
| 133 Returns the node pointer, or NULL if it's not found. | |
| 134 */ | |
| 135 { | |
| 136 register HNODE *p; /* search pointer/return from this function */ | |
| 137 | |
| 138 if (bucket<0) /* compute hash value if we don't know it already */ | |
| 139 bucket = do_hash(tab,key); | |
| 140 | |
| 141 /* search through the bucket contents */ | |
| 142 for (p=tab->buckets[bucket]; p; p=p->next) | |
| 143 if ((*(tab->cmp))(key,p->key)==0) | |
| 144 return p; /* found! */ | |
| 145 | |
| 146 return NULL; /* not found */ | |
| 147 | |
| 148 } /* end find_node */ | |
| 149 | |
| 150 static HASHTABLE_INTERNAL *handle2ptr( | |
| 151 HASHTABLE tbl) /* hash table handle */ | |
| 152 /* | |
| 153 handle2ptr converts a hash table handle into a pointer and checks its signatures | |
| 154 to make sure someone's not trying to pull a whizzer on this module. | |
| 155 */ | |
| 156 { | |
| 157 register HASHTABLE_INTERNAL *rc = (HASHTABLE_INTERNAL *)tbl; | |
| 158 if ((rc->sig1==HASH_SIG1) && (rc->sig2==HASH_SIG2)) | |
| 159 return rc; /* signatures match */ | |
| 160 else | |
| 161 return NULL; /* yIkes! */ | |
| 162 } | |
| 163 | |
| 164 /***************************************************************************** | |
| 165 * External functions | |
| 166 */ | |
| 167 | |
| 168 HASHTABLE ghash_create(int buckets, KEYHASHFUNC hash, KEYCOMPAREFUNC cmp) | |
| 169 /* | |
| 170 Description: | |
| 171 Creates a new hash table. | |
| 172 | |
| 173 Input: | |
| 174 Parameters: | |
| 175 buckets - Number of buckets to allocate for the hash table; this value | |
| 176 should be a prime number for maximum efficiency. | |
| 177 hash - Key hash code function to use. | |
| 178 cmp - Key comparison function to use. | |
| 179 | |
| 180 Output: | |
| 181 Returns: | |
| 182 NULL - Table could not be allocated. | |
| 183 Other - Handle to the new hashtable. | |
| 184 */ | |
| 185 { | |
| 186 HASHTABLE_INTERNAL *tab; /* new table structure */ | |
| 187 char *allocated; | |
| 188 | |
| 189 if (!hash || !cmp) | |
| 190 return NULL; /* bogus! */ | |
| 191 | |
| 192 if (buckets<=0) | |
| 193 buckets = HASH_NUM_BUCKETS; | |
| 194 | |
| 195 /* allocate a hash table structure */ | |
| 196 allocated = malloc(sizeof(HASHTABLE_INTERNAL) + (buckets * sizeof(HNODE *))); | |
| 197 if (!allocated) | |
| 198 return NULL; /* memory error */ | |
| 199 | |
| 200 /* fill the fields of the hash table */ | |
| 201 tab = (HASHTABLE_INTERNAL *)allocated; | |
| 202 allocated += sizeof(HASHTABLE_INTERNAL); | |
| 203 memset(tab,0,sizeof(HASHTABLE_INTERNAL)); | |
| 204 memset(allocated,0,buckets * sizeof(HNODE *)); | |
| 205 tab->sig1 = HASH_SIG1; | |
| 206 tab->hash = hash; | |
| 207 tab->cmp = cmp; | |
| 208 tab->bcount = buckets; | |
| 209 tab->buckets = (HNODE **)allocated; | |
| 210 tab->sig2 = HASH_SIG2; | |
| 211 | |
| 212 return (HASHTABLE)tab; /* Qa'pla! */ | |
| 213 | |
| 214 } /* end ghash_create */ | |
| 215 | |
| 216 void ghash_destroy(HASHTABLE tbl) | |
| 217 /* | |
| 218 Description: | |
| 219 Destroys a hash table. | |
| 220 | |
| 221 Input: | |
| 222 Parameters: | |
| 223 tbl - Table to be destroyed. | |
| 224 | |
| 225 Output: | |
| 226 Returns: | |
| 227 Nothing. | |
| 228 */ | |
| 229 { | |
| 230 HASHTABLE_INTERNAL *tab; /* new table structure */ | |
| 231 int i; /* loop counter */ | |
| 232 HNODE *p, *p2; /* temporary pointers */ | |
| 233 | |
| 234 if (!tbl) | |
| 235 return; /* bogus! */ | |
| 236 | |
| 237 /* Convert the handle to a table pointer. */ | |
| 238 tab = handle2ptr(tbl); | |
| 239 if (!tab) | |
| 240 return; | |
| 241 | |
| 242 /* Nuke the nodes it contains. */ | |
| 243 for (i=0; i<tab->bcount; i++) | |
| 244 { /* free the contents of each bucket */ | |
| 245 p = tab->buckets[i]; | |
| 246 while (p) | |
| 247 { /* free each node in turn */ | |
| 248 p2 = p->next; | |
| 249 free_node(p); | |
| 250 p = p2; | |
| 251 | |
| 252 } /* end while */ | |
| 253 | |
| 254 } /* end for */ | |
| 255 | |
| 256 free(tab); /* bye bye now! */ | |
| 257 | |
| 258 } /* end ghash_destroy */ | |
| 259 | |
| 260 void *ghash_get(HASHTABLE tbl, const void *key) | |
| 261 /* | |
| 262 Description: | |
| 263 Retrieves a value stored in the hash table. | |
| 264 | |
| 265 Input: | |
| 266 Parameters: | |
| 267 tbl - The hash table to look in. | |
| 268 key - The key value to search on. | |
| 269 | |
| 270 Output: | |
| 271 Returns: | |
| 272 NULL - Value not found. | |
| 273 Other - Value corresponding to the specified key. | |
| 274 */ | |
| 275 { | |
| 276 HASHTABLE_INTERNAL *tab; /* internal table pointer */ | |
| 277 HNODE *node; /* hash node */ | |
| 278 void *rc = NULL; /* return from this function */ | |
| 279 | |
| 280 if (!tbl || !key) | |
| 281 return NULL; /* bogus! */ | |
| 282 | |
| 283 /* Convert the handle to a table pointer. */ | |
| 284 tab = handle2ptr(tbl); | |
| 285 if (!tab) | |
| 286 return NULL; /* error */ | |
| 287 | |
| 288 /* Attempt to find the node. */ | |
| 289 node = find_node(tab,key,-1); | |
| 290 if (node) | |
| 291 rc = node->value; /* found it! */ | |
| 292 | |
| 293 return rc; | |
| 294 | |
| 295 } /* end ghash_get */ | |
| 296 | |
| 297 int ghash_put(HASHTABLE tbl, const void *key, void *value) | |
| 298 /* | |
| 299 Description: | |
| 300 Associates a key with a value in this hash table. | |
| 301 | |
| 302 Input: | |
| 303 Parameters: | |
| 304 tbl - Hash table to add. | |
| 305 key - Key to use for the value in the table. | |
| 306 value - Value to add for this key. | |
| 307 | |
| 308 Output: | |
| 309 Returns: | |
| 310 1 - Success. | |
| 311 0 - Failure. | |
| 312 | |
| 313 Notes: | |
| 314 If the specified key is already in the hashtable, its value will be replaced. | |
| 315 */ | |
| 316 { | |
| 317 HASHTABLE_INTERNAL *tab; /* internal table pointer */ | |
| 318 int bucket; /* bucket value goes into */ | |
| 319 HNODE *node; /* hash node */ | |
| 320 int rc = 1; /* return from this function */ | |
| 321 | |
| 322 if (!tbl || !key || !value) | |
| 323 return 0; /* bogus! */ | |
| 324 | |
| 325 /* Convert the handle to a table pointer. */ | |
| 326 tab = handle2ptr(tbl); | |
| 327 if (!tab) | |
| 328 return 0; /* error */ | |
| 329 | |
| 330 | |
| 331 /* Compute the hash bucket and try to find an existing node. */ | |
| 332 bucket = do_hash(tab,key); | |
| 333 node = find_node(tab,key,bucket); | |
| 334 if (!node) | |
| 335 { /* OK, try to allocate a new node. */ | |
| 336 node = allocate_node(key,value); | |
| 337 if (node) | |
| 338 { /* Chain the new node into the hash table. */ | |
| 339 node->next = tab->buckets[bucket]; | |
| 340 tab->buckets[bucket] = node; | |
| 341 tab->count++; | |
| 342 | |
| 343 } /* end if */ | |
| 344 else /* allocation error */ | |
| 345 rc = 0; | |
| 346 | |
| 347 } /* end if */ | |
| 348 else /* already in table - just reassign value */ | |
| 349 node->value = value; | |
| 350 | |
| 351 return rc; | |
| 352 | |
| 353 } /* end ghash_put */ | |
| 354 | |
| 355 int ghash_remove(HASHTABLE tbl, const void *key) | |
| 356 /* | |
| 357 Description: | |
| 358 Removes an entry from a hash table, given its key. | |
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359 |
| 25 | 360 Input: |
| 361 Parameters: | |
| 362 tbl - Hash table to remove from. | |
| 363 key - Key of value to remove. | |
| 364 | |
| 365 Output: | |
| 366 Returns: | |
| 367 1 - Success. | |
| 368 0 - Failure; key not present in hash table. | |
| 369 */ | |
| 370 { | |
| 371 HASHTABLE_INTERNAL *tab; /* internal table pointer */ | |
| 372 int bucket; /* bucket value goes into */ | |
| 373 HNODE *node; /* hash node */ | |
| 374 register HNODE *p; /* removal pointer */ | |
| 375 int rc = 1; /* return from this function */ | |
| 376 | |
| 377 if (!tbl || !key) | |
| 378 return 0; /* bogus! */ | |
| 379 | |
| 380 /* Convert the handle to a table pointer. */ | |
| 381 tab = handle2ptr(tbl); | |
| 382 if (!tab) | |
| 383 return 0; /* error */ | |
| 384 | |
| 385 | |
| 386 /* Compute the hash bucket and try to find an existing node. */ | |
| 387 bucket = do_hash(tab,key); | |
| 388 node = find_node(tab,key,bucket); | |
| 389 if (node) | |
| 390 { /* look to unchain it from the bucket it's in */ | |
| 391 if (node==tab->buckets[bucket]) | |
| 392 tab->buckets[bucket] = node->next; /* unchain at head */ | |
| 393 else | |
| 394 { /* unchain in middle of list */ | |
| 395 for (p=tab->buckets[bucket]; p->next!=node; p=p->next) ; | |
| 396 p->next = node->next; | |
| 397 | |
| 398 } /* end else */ | |
| 399 | |
| 400 free_node(node); /* bye bye now! */ | |
| 401 tab->count--; | |
| 402 | |
| 403 } /* end if */ | |
| 404 else /* node not found */ | |
| 405 rc = 0; | |
| 406 | |
| 407 return rc; | |
| 408 | |
| 409 } /* end ghash_remove */ | |
| 410 | |
| 411 int ghash_walk(HASHTABLE tbl, TABLEWALKFUNC func, void *user_data) | |
| 412 /* | |
| 413 Description: | |
| 414 "Walks" through a hash table, calling a callback function for each element | |
| 415 stored in it. | |
| 416 | |
| 417 Input: | |
| 418 Parameters: | |
| 419 tbl - Hash table to walk. | |
| 420 func - Function to be called for each node. It takes three parameters, | |
| 421 a user data pointer, a key value pointer, and a data value pointer. | |
| 422 It returns 0 to stop the enumeration or 1 to keep it going. | |
| 423 user_data - Value to use as the first parameter for the callback | |
| 424 function. | |
| 425 | |
| 426 Output: | |
| 427 Returns: | |
| 428 0 - Error occurred. | |
| 429 Other - Number of nodes visited up to and including the one for which | |
| 430 the callback function returned 0, if it did; ranges from 1 | |
| 431 to the number of nodes in the hashtable. | |
| 432 */ | |
| 433 { | |
| 434 HASHTABLE_INTERNAL *tab; /* internal table pointer */ | |
| 435 int i; /* loop counter */ | |
| 436 int running = 1; /* we're still running */ | |
| 437 int count = 0; /* number of nodes visited before stop node */ | |
| 438 register HNODE *p, *p2; /* loop pointer */ | |
| 439 | |
| 440 if (!tbl || !func) | |
| 441 return -1; /* bogus values! */ | |
| 442 | |
| 443 /* Convert the handle to a table pointer. */ | |
| 444 tab = handle2ptr(tbl); | |
| 445 if (!tab) | |
| 446 return -1; /* error */ | |
| 447 | |
| 448 | |
| 449 for (i=0; running && (i<tab->bcount); i++) | |
| 450 { /* visit the contents of each bucket */ | |
| 451 p = tab->buckets[i]; | |
| 452 while (running && p) | |
| 453 { /* visit each node in turn */ | |
| 454 p2 = p->next; | |
| 455 count++; | |
| 456 running = (*func)(user_data,p->key,p->value); | |
| 457 p = p2; | |
| 458 | |
| 459 } /* end while */ | |
| 460 | |
| 461 } /* end for */ | |
| 462 | |
| 463 return count; | |
| 464 | |
| 465 } /* end ghash_walk */ | |
| 466 | |
| 467 int str_hash_code(const char *s) | |
| 468 /* | |
| 469 Description: | |
| 470 Generates a hash code for a string. This function uses the ELF hashing | |
| 471 algorithm as reprinted in Andrew Binstock, "Hashing Rehashed," _Dr. | |
| 472 Dobb's Journal_, April 1996. | |
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473 |
| 25 | 474 Input: |
| 475 Parameters: | |
| 476 s - The string to be hashed. | |
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477 |
| 25 | 478 Output: |
| 479 Returns: | |
| 480 A hash code for the string. | |
| 481 */ | |
| 482 { | |
| 483 /* ELF hash uses unsigned chars and unsigned arithmetic for portability */ | |
| 484 const unsigned char *name = (const unsigned char *)s; | |
| 485 unsigned long h = 0, g; | |
| 486 | |
| 487 if (!name) | |
| 488 return 0; /* anti-NULL guard not in the original */ | |
| 489 | |
| 490 while (*name) | |
| 491 { /* do some fancy bitwanking on the string */ | |
| 492 h = (h << 4) + (unsigned long)(*name++); | |
| 493 if ((g = (h & 0xF0000000UL))!=0) | |
| 494 h ^= (g >> 24); | |
| 495 h &= ~g; | |
| 496 | |
| 497 } /* end while */ | |
| 498 | |
| 499 return (int)h; | |
| 500 | |
| 501 } |