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a2f945c6 | 1 | /* An expandable hash tables datatype. |
b13eb66b | 2 | Copyright (C) 1999, 2000 Free Software Foundation, Inc. |
a2f945c6 VM |
3 | Contributed by Vladimir Makarov (vmakarov@cygnus.com). |
4 | ||
5 | This file is part of the libiberty library. | |
6 | Libiberty is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Library General Public | |
8 | License as published by the Free Software Foundation; either | |
9 | version 2 of the License, or (at your option) any later version. | |
10 | ||
11 | Libiberty is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Library General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Library General Public | |
17 | License along with libiberty; see the file COPYING.LIB. If | |
18 | not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | /* This package implements basic hash table functionality. It is possible | |
22 | to search for an entry, create an entry and destroy an entry. | |
23 | ||
24 | Elements in the table are generic pointers. | |
25 | ||
26 | The size of the table is not fixed; if the occupancy of the table | |
27 | grows too high the hash table will be expanded. | |
28 | ||
29 | The abstract data implementation is based on generalized Algorithm D | |
30 | from Knuth's book "The art of computer programming". Hash table is | |
31 | expanded by creation of new hash table and transferring elements from | |
32 | the old table to the new table. */ | |
33 | ||
34 | #ifdef HAVE_CONFIG_H | |
35 | #include "config.h" | |
36 | #endif | |
37 | ||
6de9b8ff PDM |
38 | #include <sys/types.h> |
39 | ||
a2f945c6 VM |
40 | #ifdef HAVE_STDLIB_H |
41 | #include <stdlib.h> | |
42 | #endif | |
43 | ||
d11ec6f0 ZW |
44 | #ifdef HAVE_STRING_H |
45 | #include <string.h> | |
46 | #endif | |
47 | ||
36dd3a44 JL |
48 | #include <stdio.h> |
49 | ||
a2f945c6 VM |
50 | #include "libiberty.h" |
51 | #include "hashtab.h" | |
52 | ||
a2f945c6 VM |
53 | /* This macro defines reserved value for empty table entry. */ |
54 | ||
5194cf08 | 55 | #define EMPTY_ENTRY ((void *) 0) |
a2f945c6 VM |
56 | |
57 | /* This macro defines reserved value for table entry which contained | |
58 | a deleted element. */ | |
59 | ||
60 | #define DELETED_ENTRY ((void *) 1) | |
61 | ||
0194e877 | 62 | static unsigned long higher_prime_number PARAMS ((unsigned long)); |
18a94a2f MM |
63 | static hashval_t hash_pointer PARAMS ((const void *)); |
64 | static int eq_pointer PARAMS ((const void *, const void *)); | |
8e02c4d0 JH |
65 | static void htab_expand PARAMS ((htab_t)); |
66 | static void **find_empty_slot_for_expand PARAMS ((htab_t, hashval_t)); | |
18a94a2f MM |
67 | |
68 | /* At some point, we could make these be NULL, and modify the | |
69 | hash-table routines to handle NULL specially; that would avoid | |
70 | function-call overhead for the common case of hashing pointers. */ | |
71 | htab_hash htab_hash_pointer = hash_pointer; | |
72 | htab_eq htab_eq_pointer = eq_pointer; | |
0194e877 | 73 | |
a2f945c6 | 74 | /* The following function returns the nearest prime number which is |
e38992e8 | 75 | greater than a given source number, N. */ |
a2f945c6 VM |
76 | |
77 | static unsigned long | |
5194cf08 ZW |
78 | higher_prime_number (n) |
79 | unsigned long n; | |
a2f945c6 VM |
80 | { |
81 | unsigned long i; | |
82 | ||
e38992e8 RK |
83 | /* Ensure we have a larger number and then force to odd. */ |
84 | n++; | |
85 | n |= 0x01; | |
86 | ||
87 | /* All odd numbers < 9 are prime. */ | |
5194cf08 | 88 | if (n < 9) |
e38992e8 RK |
89 | return n; |
90 | ||
91 | /* Otherwise find the next prime using a sieve. */ | |
5194cf08 ZW |
92 | |
93 | next: | |
e38992e8 RK |
94 | |
95 | for (i = 3; i * i <= n; i += 2) | |
96 | if (n % i == 0) | |
97 | { | |
98 | n += 2; | |
99 | goto next; | |
100 | } | |
5194cf08 ZW |
101 | |
102 | return n; | |
a2f945c6 VM |
103 | } |
104 | ||
18a94a2f MM |
105 | /* Returns a hash code for P. */ |
106 | ||
4feeaae3 | 107 | static hashval_t |
18a94a2f MM |
108 | hash_pointer (p) |
109 | const void *p; | |
110 | { | |
1d2da2e1 | 111 | return (hashval_t) ((long)p >> 3); |
18a94a2f MM |
112 | } |
113 | ||
114 | /* Returns non-zero if P1 and P2 are equal. */ | |
115 | ||
4feeaae3 | 116 | static int |
18a94a2f MM |
117 | eq_pointer (p1, p2) |
118 | const void *p1; | |
119 | const void *p2; | |
120 | { | |
121 | return p1 == p2; | |
122 | } | |
123 | ||
a2f945c6 VM |
124 | /* This function creates table with length slightly longer than given |
125 | source length. Created hash table is initiated as empty (all the | |
126 | hash table entries are EMPTY_ENTRY). The function returns the | |
127 | created hash table. */ | |
128 | ||
5194cf08 | 129 | htab_t |
5dc9cffd | 130 | htab_create (size, hash_f, eq_f, del_f) |
a2f945c6 | 131 | size_t size; |
5194cf08 ZW |
132 | htab_hash hash_f; |
133 | htab_eq eq_f; | |
5dc9cffd | 134 | htab_del del_f; |
a2f945c6 | 135 | { |
5194cf08 | 136 | htab_t result; |
a2f945c6 VM |
137 | |
138 | size = higher_prime_number (size); | |
5194cf08 ZW |
139 | result = (htab_t) xcalloc (1, sizeof (struct htab)); |
140 | result->entries = (void **) xcalloc (size, sizeof (void *)); | |
a2f945c6 | 141 | result->size = size; |
5194cf08 ZW |
142 | result->hash_f = hash_f; |
143 | result->eq_f = eq_f; | |
5dc9cffd | 144 | result->del_f = del_f; |
a2f945c6 VM |
145 | return result; |
146 | } | |
147 | ||
148 | /* This function frees all memory allocated for given hash table. | |
149 | Naturally the hash table must already exist. */ | |
150 | ||
151 | void | |
5194cf08 ZW |
152 | htab_delete (htab) |
153 | htab_t htab; | |
a2f945c6 | 154 | { |
5dc9cffd | 155 | int i; |
e38992e8 | 156 | |
5dc9cffd ZW |
157 | if (htab->del_f) |
158 | for (i = htab->size - 1; i >= 0; i--) | |
e38992e8 RK |
159 | if (htab->entries[i] != EMPTY_ENTRY |
160 | && htab->entries[i] != DELETED_ENTRY) | |
161 | (*htab->del_f) (htab->entries[i]); | |
5dc9cffd | 162 | |
a2f945c6 VM |
163 | free (htab->entries); |
164 | free (htab); | |
165 | } | |
166 | ||
167 | /* This function clears all entries in the given hash table. */ | |
168 | ||
169 | void | |
5194cf08 ZW |
170 | htab_empty (htab) |
171 | htab_t htab; | |
a2f945c6 | 172 | { |
5dc9cffd | 173 | int i; |
e38992e8 | 174 | |
5dc9cffd ZW |
175 | if (htab->del_f) |
176 | for (i = htab->size - 1; i >= 0; i--) | |
e38992e8 RK |
177 | if (htab->entries[i] != EMPTY_ENTRY |
178 | && htab->entries[i] != DELETED_ENTRY) | |
179 | (*htab->del_f) (htab->entries[i]); | |
5dc9cffd | 180 | |
5194cf08 | 181 | memset (htab->entries, 0, htab->size * sizeof (void *)); |
a2f945c6 VM |
182 | } |
183 | ||
8c5d513f BS |
184 | /* Similar to htab_find_slot, but without several unwanted side effects: |
185 | - Does not call htab->eq_f when it finds an existing entry. | |
186 | - Does not change the count of elements/searches/collisions in the | |
187 | hash table. | |
188 | This function also assumes there are no deleted entries in the table. | |
189 | HASH is the hash value for the element to be inserted. */ | |
e38992e8 | 190 | |
8c5d513f BS |
191 | static void ** |
192 | find_empty_slot_for_expand (htab, hash) | |
193 | htab_t htab; | |
b13eb66b | 194 | hashval_t hash; |
8c5d513f BS |
195 | { |
196 | size_t size = htab->size; | |
b13eb66b | 197 | hashval_t hash2 = 1 + hash % (size - 2); |
8c5d513f BS |
198 | unsigned int index = hash % size; |
199 | ||
200 | for (;;) | |
201 | { | |
202 | void **slot = htab->entries + index; | |
e38992e8 | 203 | |
8c5d513f BS |
204 | if (*slot == EMPTY_ENTRY) |
205 | return slot; | |
e38992e8 | 206 | else if (*slot == DELETED_ENTRY) |
8c5d513f BS |
207 | abort (); |
208 | ||
209 | index += hash2; | |
210 | if (index >= size) | |
211 | index -= size; | |
212 | } | |
213 | } | |
214 | ||
a2f945c6 VM |
215 | /* The following function changes size of memory allocated for the |
216 | entries and repeatedly inserts the table elements. The occupancy | |
217 | of the table after the call will be about 50%. Naturally the hash | |
218 | table must already exist. Remember also that the place of the | |
219 | table entries is changed. */ | |
220 | ||
221 | static void | |
5194cf08 ZW |
222 | htab_expand (htab) |
223 | htab_t htab; | |
a2f945c6 | 224 | { |
5194cf08 ZW |
225 | void **oentries; |
226 | void **olimit; | |
227 | void **p; | |
228 | ||
229 | oentries = htab->entries; | |
230 | olimit = oentries + htab->size; | |
231 | ||
232 | htab->size = higher_prime_number (htab->size * 2); | |
4feeaae3 | 233 | htab->entries = (void **) xcalloc (htab->size, sizeof (void **)); |
5194cf08 ZW |
234 | |
235 | htab->n_elements -= htab->n_deleted; | |
236 | htab->n_deleted = 0; | |
237 | ||
238 | p = oentries; | |
239 | do | |
240 | { | |
241 | void *x = *p; | |
e38992e8 | 242 | |
5194cf08 ZW |
243 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) |
244 | { | |
8c5d513f | 245 | void **q = find_empty_slot_for_expand (htab, (*htab->hash_f) (x)); |
e38992e8 | 246 | |
5194cf08 ZW |
247 | *q = x; |
248 | } | |
e38992e8 | 249 | |
5194cf08 ZW |
250 | p++; |
251 | } | |
252 | while (p < olimit); | |
e38992e8 | 253 | |
5194cf08 | 254 | free (oentries); |
a2f945c6 VM |
255 | } |
256 | ||
5194cf08 ZW |
257 | /* This function searches for a hash table entry equal to the given |
258 | element. It cannot be used to insert or delete an element. */ | |
259 | ||
260 | void * | |
8c5d513f | 261 | htab_find_with_hash (htab, element, hash) |
5194cf08 ZW |
262 | htab_t htab; |
263 | const void *element; | |
b13eb66b | 264 | hashval_t hash; |
a2f945c6 | 265 | { |
b13eb66b MM |
266 | unsigned int index; |
267 | hashval_t hash2; | |
5194cf08 | 268 | size_t size; |
0194e877 | 269 | void *entry; |
5194cf08 ZW |
270 | |
271 | htab->searches++; | |
272 | size = htab->size; | |
5194cf08 | 273 | index = hash % size; |
a2f945c6 | 274 | |
0194e877 ZW |
275 | entry = htab->entries[index]; |
276 | if (entry == EMPTY_ENTRY | |
277 | || (entry != DELETED_ENTRY && (*htab->eq_f) (entry, element))) | |
278 | return entry; | |
279 | ||
280 | hash2 = 1 + hash % (size - 2); | |
281 | ||
5194cf08 | 282 | for (;;) |
a2f945c6 | 283 | { |
5194cf08 ZW |
284 | htab->collisions++; |
285 | index += hash2; | |
286 | if (index >= size) | |
287 | index -= size; | |
0194e877 ZW |
288 | |
289 | entry = htab->entries[index]; | |
290 | if (entry == EMPTY_ENTRY | |
291 | || (entry != DELETED_ENTRY && (*htab->eq_f) (entry, element))) | |
292 | return entry; | |
a2f945c6 | 293 | } |
5194cf08 ZW |
294 | } |
295 | ||
8c5d513f BS |
296 | /* Like htab_find_slot_with_hash, but compute the hash value from the |
297 | element. */ | |
e38992e8 | 298 | |
8c5d513f BS |
299 | void * |
300 | htab_find (htab, element) | |
301 | htab_t htab; | |
302 | const void *element; | |
303 | { | |
304 | return htab_find_with_hash (htab, element, (*htab->hash_f) (element)); | |
305 | } | |
306 | ||
5194cf08 ZW |
307 | /* This function searches for a hash table slot containing an entry |
308 | equal to the given element. To delete an entry, call this with | |
309 | INSERT = 0, then call htab_clear_slot on the slot returned (possibly | |
310 | after doing some checks). To insert an entry, call this with | |
311 | INSERT = 1, then write the value you want into the returned slot. */ | |
312 | ||
313 | void ** | |
8c5d513f | 314 | htab_find_slot_with_hash (htab, element, hash, insert) |
5194cf08 ZW |
315 | htab_t htab; |
316 | const void *element; | |
b13eb66b | 317 | hashval_t hash; |
e38992e8 | 318 | enum insert_option insert; |
5194cf08 ZW |
319 | { |
320 | void **first_deleted_slot; | |
b13eb66b MM |
321 | unsigned int index; |
322 | hashval_t hash2; | |
5194cf08 ZW |
323 | size_t size; |
324 | ||
e38992e8 | 325 | if (insert == INSERT && htab->size * 3 <= htab->n_elements * 4) |
5194cf08 ZW |
326 | htab_expand (htab); |
327 | ||
328 | size = htab->size; | |
5194cf08 ZW |
329 | hash2 = 1 + hash % (size - 2); |
330 | index = hash % size; | |
331 | ||
a2f945c6 | 332 | htab->searches++; |
5194cf08 ZW |
333 | first_deleted_slot = NULL; |
334 | ||
335 | for (;;) | |
a2f945c6 | 336 | { |
5194cf08 ZW |
337 | void *entry = htab->entries[index]; |
338 | if (entry == EMPTY_ENTRY) | |
339 | { | |
e38992e8 | 340 | if (insert == NO_INSERT) |
5194cf08 ZW |
341 | return NULL; |
342 | ||
343 | htab->n_elements++; | |
344 | ||
345 | if (first_deleted_slot) | |
a2f945c6 | 346 | { |
5194cf08 ZW |
347 | *first_deleted_slot = EMPTY_ENTRY; |
348 | return first_deleted_slot; | |
a2f945c6 | 349 | } |
5194cf08 ZW |
350 | |
351 | return &htab->entries[index]; | |
352 | } | |
353 | ||
354 | if (entry == DELETED_ENTRY) | |
355 | { | |
356 | if (!first_deleted_slot) | |
357 | first_deleted_slot = &htab->entries[index]; | |
358 | } | |
e38992e8 RK |
359 | else if ((*htab->eq_f) (entry, element)) |
360 | return &htab->entries[index]; | |
5194cf08 ZW |
361 | |
362 | htab->collisions++; | |
363 | index += hash2; | |
364 | if (index >= size) | |
365 | index -= size; | |
a2f945c6 | 366 | } |
a2f945c6 VM |
367 | } |
368 | ||
8c5d513f BS |
369 | /* Like htab_find_slot_with_hash, but compute the hash value from the |
370 | element. */ | |
e38992e8 | 371 | |
8c5d513f BS |
372 | void ** |
373 | htab_find_slot (htab, element, insert) | |
374 | htab_t htab; | |
375 | const void *element; | |
e38992e8 | 376 | enum insert_option insert; |
8c5d513f BS |
377 | { |
378 | return htab_find_slot_with_hash (htab, element, (*htab->hash_f) (element), | |
379 | insert); | |
380 | } | |
381 | ||
5194cf08 ZW |
382 | /* This function deletes an element with the given value from hash |
383 | table. If there is no matching element in the hash table, this | |
384 | function does nothing. */ | |
a2f945c6 VM |
385 | |
386 | void | |
5194cf08 ZW |
387 | htab_remove_elt (htab, element) |
388 | htab_t htab; | |
389 | void *element; | |
a2f945c6 | 390 | { |
5194cf08 | 391 | void **slot; |
a2f945c6 | 392 | |
e38992e8 | 393 | slot = htab_find_slot (htab, element, NO_INSERT); |
5194cf08 ZW |
394 | if (*slot == EMPTY_ENTRY) |
395 | return; | |
396 | ||
5dc9cffd ZW |
397 | if (htab->del_f) |
398 | (*htab->del_f) (*slot); | |
399 | ||
5194cf08 ZW |
400 | *slot = DELETED_ENTRY; |
401 | htab->n_deleted++; | |
a2f945c6 VM |
402 | } |
403 | ||
5194cf08 ZW |
404 | /* This function clears a specified slot in a hash table. It is |
405 | useful when you've already done the lookup and don't want to do it | |
406 | again. */ | |
ed38f5d5 ZW |
407 | |
408 | void | |
5194cf08 ZW |
409 | htab_clear_slot (htab, slot) |
410 | htab_t htab; | |
411 | void **slot; | |
ed38f5d5 ZW |
412 | { |
413 | if (slot < htab->entries || slot >= htab->entries + htab->size | |
414 | || *slot == EMPTY_ENTRY || *slot == DELETED_ENTRY) | |
415 | abort (); | |
e38992e8 | 416 | |
5dc9cffd ZW |
417 | if (htab->del_f) |
418 | (*htab->del_f) (*slot); | |
e38992e8 | 419 | |
ed38f5d5 | 420 | *slot = DELETED_ENTRY; |
5194cf08 | 421 | htab->n_deleted++; |
ed38f5d5 ZW |
422 | } |
423 | ||
424 | /* This function scans over the entire hash table calling | |
425 | CALLBACK for each live entry. If CALLBACK returns false, | |
426 | the iteration stops. INFO is passed as CALLBACK's second | |
427 | argument. */ | |
428 | ||
429 | void | |
5194cf08 ZW |
430 | htab_traverse (htab, callback, info) |
431 | htab_t htab; | |
432 | htab_trav callback; | |
ed38f5d5 ZW |
433 | void *info; |
434 | { | |
e38992e8 RK |
435 | void **slot = htab->entries; |
436 | void **limit = slot + htab->size; | |
437 | ||
5194cf08 ZW |
438 | do |
439 | { | |
440 | void *x = *slot; | |
e38992e8 | 441 | |
5194cf08 | 442 | if (x != EMPTY_ENTRY && x != DELETED_ENTRY) |
8c5d513f | 443 | if (!(*callback) (slot, info)) |
5194cf08 ZW |
444 | break; |
445 | } | |
446 | while (++slot < limit); | |
ed38f5d5 ZW |
447 | } |
448 | ||
e38992e8 | 449 | /* Return the current size of given hash table. */ |
a2f945c6 VM |
450 | |
451 | size_t | |
5194cf08 ZW |
452 | htab_size (htab) |
453 | htab_t htab; | |
a2f945c6 VM |
454 | { |
455 | return htab->size; | |
456 | } | |
457 | ||
e38992e8 | 458 | /* Return the current number of elements in given hash table. */ |
a2f945c6 VM |
459 | |
460 | size_t | |
5194cf08 ZW |
461 | htab_elements (htab) |
462 | htab_t htab; | |
a2f945c6 | 463 | { |
5194cf08 | 464 | return htab->n_elements - htab->n_deleted; |
a2f945c6 VM |
465 | } |
466 | ||
e38992e8 RK |
467 | /* Return the fraction of fixed collisions during all work with given |
468 | hash table. */ | |
a2f945c6 | 469 | |
5194cf08 ZW |
470 | double |
471 | htab_collisions (htab) | |
472 | htab_t htab; | |
a2f945c6 | 473 | { |
e38992e8 | 474 | if (htab->searches == 0) |
5194cf08 | 475 | return 0.0; |
e38992e8 RK |
476 | |
477 | return (double) htab->collisions / (double) htab->searches; | |
a2f945c6 | 478 | } |