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