3 * File name: ir/adt/set.c
4 * Purpose: Set --- collection of entries that are unique wrt to a key.
5 * Author: Markus Armbruster
7 * Created: 1999 by getting from fiasco
9 * Copyright: (c) 1995, 1996 Markus Armbruster
10 * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
13 /* This code is derived from:
15 From: ejp@ausmelb.oz.AU (Esmond Pitt)
16 Date: Tue, 7 Mar 1989 22:06:26 GMT
17 Subject: v06i042: dynamic hashing version of hsearch(3)
18 Message-ID: <1821@basser.oz>
19 Newsgroups: comp.sources.misc
20 Sender: msgs@basser.oz
22 Posting-number: Volume 6, Issue 42
23 Submitted-By: Esmond Pitt <ejp@ausmelb.oz.AU>
24 Archive-name: dynamic-hash
26 * Dynamic hashing, after CACM April 1988 pp 446-457, by Per-Ake Larson.
27 * Coded into C, with minor code improvements, and with hsearch(3) interface,
28 * by ejp@ausmelb.oz, Jul 26, 1988: 13:16;
30 TODO: Fix Esmond's ugly MixedCapsIdentifiers ;->
39 /* bcopy is not ISO C *
40 #define bcopy(X, Y, Z) memcpy((Y), (X), (Z))
45 # define PMANGLE(pre) pre##_pset
46 # define MANGLEP(post) pset_##post
47 # define MANGLE(pre, post) pre##pset##post
48 # define EQUAL(cmp, elt, key, siz) (!(cmp) ((elt)->entry.dptr, (key)))
51 # define PMANGLE(pre) pre##_set
52 # define MANGLEP(post) set_##post
53 # define MANGLE(pre, post) pre##set##post
54 # define EQUAL(cmp, elt, key, siz) \
55 (((elt)->entry.size == (siz)) && !(cmp) ((elt)->entry.dptr, (key), (siz)))
70 #define TOBSTACK_ID MANGLEP(tag)
74 #define SEGMENT_SIZE_SHIFT 8
75 #define SEGMENT_SIZE (1 << SEGMENT_SIZE_SHIFT)
76 #define DIRECTORY_SIZE_SHIFT 8
77 #define DIRECTORY_SIZE (1 << DIRECTORY_SIZE_SHIFT)
78 #define MAX_LOAD_FACTOR 4
81 typedef struct element {
82 struct element *chain; /* for chaining Elements */
83 MANGLEP (entry) entry;
88 unsigned p; /* Next bucket to be split */
89 unsigned maxp; /* upper bound on p during expansion */
90 unsigned nkey; /* current # keys */
91 unsigned nseg; /* current # segments */
92 Segment *dir[DIRECTORY_SIZE];
93 MANGLEP(cmp_fun) cmp; /* function comparing entries */
94 unsigned iter_i, iter_j;
95 Element *iter_tail; /* non-NULL while iterating over elts */
97 Element *free_list; /* list of free Elements */
99 struct obstack obst; /* obstack for allocation all data */
101 int naccess, ncollision, ndups;
113 MANGLEP(stats) (SET *table)
117 Element *q = table->free_list;
118 while (q) { q = q->chain; ++nfree; }
120 printf (" accesses collisions keys duplicates longest wasted\n%12d%12d%12d%12d%12d%12d\n",
121 table->naccess, table->ncollision, table->nkey, table->ndups, table->max_chain_len, nfree);
125 stat_chain_len (SET *table, int chain_len)
127 table->ncollision += chain_len;
128 if (table->max_chain_len < chain_len) table->max_chain_len = chain_len;
131 # define stat_access(table) (++(table)->naccess)
132 # define stat_dup(table) (++(table)->ndups)
136 # define stat_chain_len(table, chain_len) ((void)0)
137 # define stat_access(table) ((void)0)
138 # define stat_dup(table) ((void)0)
144 const char *MANGLEP(tag);
148 MANGLEP(describe) (SET *table)
150 unsigned i, j, collide;
154 printf ("p=%u maxp=%u nkey=%u nseg=%u\n",
155 table->p, table->maxp, table->nkey, table->nseg);
156 for (i = 0; i < table->nseg; i++) {
158 for (j = 0; j < SEGMENT_SIZE; j++) {
162 if (collide) printf ("<%3d>", collide);
163 else printf ("table");
164 printf ("[%d][%3d]: %u %p\n", i, j, ptr->entry.hash, ptr->entry.dptr);
176 (PMANGLE(new)) (MANGLEP(cmp_fun) cmp, int nslots)
179 SET *table = xmalloc (sizeof (SET));
181 if (nslots > SEGMENT_SIZE * DIRECTORY_SIZE)
182 nslots = SEGMENT_SIZE * DIRECTORY_SIZE;
184 assert (nslots >= 0);
185 /* Adjust nslots up to next power of 2, minimum SEGMENT_SIZE */
186 for (i = SEGMENT_SIZE; i < nslots; i <<= 1);
188 nslots = i >> SEGMENT_SIZE_SHIFT;
190 table->nseg = table->p = table->nkey = 0;
191 table->maxp = nslots << SEGMENT_SIZE_SHIFT;
193 table->iter_tail = NULL;
195 table->free_list = NULL;
197 obstack_init (&table->obst);
200 for (i = 0; i < nslots; ++i) {
201 table->dir[i] = (Segment *)obstack_alloc (&table->obst,
202 sizeof (Segment) * SEGMENT_SIZE);
204 memset(table->dir[i], 0, sizeof (Segment) * SEGMENT_SIZE);
209 table->naccess = table->ncollision = table->ndups = 0;
210 table->max_chain_len = 0;
213 table->tag = MANGLEP(tag);
220 PMANGLE(del) (SET *table)
223 MANGLEP(tag) = table->tag;
225 obstack_free (&table->obst, NULL);
230 MANGLEP(count) (SET *table)
236 * do one iteration step, return 1
237 * if still data in the set, 0 else
240 iter_step (SET *table)
242 if (++table->iter_j >= SEGMENT_SIZE) {
244 if (++table->iter_i >= table->nseg) {
253 * finds the first entry in the table
256 MANGLEP(first) (SET *table)
258 assert (!table->iter_tail);
261 while (!table->dir[table->iter_i][table->iter_j]) {
262 if (!iter_step (table)) return NULL;
264 table->iter_tail = table->dir[table->iter_i][table->iter_j];
265 assert (table->iter_tail->entry.dptr);
266 return table->iter_tail->entry.dptr;
270 * returns next entry in the table
273 MANGLEP(next) (SET *table)
275 if (!table->iter_tail)
278 /* follow collision chain */
279 table->iter_tail = table->iter_tail->chain;
280 if (!table->iter_tail) {
281 /* go to next segment */
283 if (!iter_step (table)) return NULL;
284 } while (!table->dir[table->iter_i][table->iter_j]);
285 table->iter_tail = table->dir[table->iter_i][table->iter_j];
287 assert (table->iter_tail->entry.dptr);
288 return table->iter_tail->entry.dptr;
292 MANGLEP(break) (SET *table)
294 table->iter_tail = NULL;
298 * limit the hash value
300 static INLINE unsigned
301 Hash (SET *table, unsigned h)
305 address = h & (table->maxp - 1); /* h % table->maxp */
306 if (address < (unsigned)table->p)
307 address = h & ((table->maxp << 1) - 1); /* h % (2*table->maxp) */
312 * returns non-zero if the number of elements in
313 * the set is greater then number of segments * MAX_LOAD_FACTOR
318 return ( ++table->nkey
319 > (table->nseg << SEGMENT_SIZE_SHIFT) * MAX_LOAD_FACTOR);
323 * expand the hash-table: the algorithm is split, so on every
324 * insert, only ONE segment is rehashed!
326 * table->p contains the current segment to split
327 * after all segments were split, table->p is set to zero and
328 * table->maxp is duplicated.
331 expand_table (SET *table)
334 int OldSegmentIndex, NewSegmentIndex;
335 int OldSegmentDir, NewSegmentDir;
342 if (table->maxp + table->p < (DIRECTORY_SIZE << SEGMENT_SIZE_SHIFT)) {
343 /* Locate the bucket to be split */
344 OldSegmentDir = table->p >> SEGMENT_SIZE_SHIFT;
345 OldSegment = table->dir[OldSegmentDir];
346 OldSegmentIndex = table->p & (SEGMENT_SIZE-1);
348 /* Expand address space; if necessary create a new segment */
349 NewAddress = table->maxp + table->p;
350 NewSegmentDir = NewAddress >> SEGMENT_SIZE_SHIFT;
351 NewSegmentIndex = NewAddress & (SEGMENT_SIZE-1);
352 if (NewSegmentIndex == 0) {
353 table->dir[NewSegmentDir] =
354 (Segment *)obstack_alloc (&table->obst,
355 sizeof(Segment) * SEGMENT_SIZE);
356 memset(table->dir[NewSegmentDir], 0, sizeof(Segment) * SEGMENT_SIZE);
359 NewSegment = table->dir[NewSegmentDir];
361 /* Adjust state variables */
363 if (table->p == table->maxp) {
364 table->maxp <<= 1; /* table->maxp *= 2 */
368 /* Relocate records to the new bucket */
369 Previous = &OldSegment[OldSegmentIndex];
371 LastOfNew = &NewSegment[NewSegmentIndex];
373 while (Current != NULL) {
374 if (Hash (table, Current->entry.hash) == NewAddress) {
375 /* move to new chain */
376 *LastOfNew = Current;
377 *Previous = Current->chain;
378 LastOfNew = &Current->chain;
379 Current = Current->chain;
382 /* leave on old chain */
383 Previous = &Current->chain;
384 Current = Current->chain;
392 MANGLE(_,_search) (SET *table,
398 MANGLE(_,_action) action)
401 Segment *CurrentSegment;
403 MANGLEP(cmp_fun) cmp = table->cmp;
408 assert (!table->iter_tail);
411 MANGLEP(tag) = table->tag;
415 /* Find collision chain */
416 h = Hash (table, hash);
417 SegmentIndex = h & (SEGMENT_SIZE-1);
418 CurrentSegment = table->dir[h >> SEGMENT_SIZE_SHIFT];
419 assert (CurrentSegment != NULL);
420 q = CurrentSegment[SegmentIndex];
422 /* Follow collision chain */
423 while (q && !EQUAL (cmp, q, key, size)) {
428 stat_chain_len (table, chain_len);
430 if (!q && (action != MANGLE(_,_find))) { /* not found, insert */
431 if (CurrentSegment[SegmentIndex]) stat_dup (table);
434 if (table->free_list) {
435 q = table->free_list;
436 table->free_list = table->free_list->chain;
438 q = obstack_alloc (&table->obst, sizeof (Element));
440 q->entry.dptr = (void *)key;
442 obstack_blank (&table->obst, offsetof (Element, entry.dptr));
443 if (action == _set_hinsert0)
444 obstack_grow0 (&table->obst, key, size);
446 obstack_grow (&table->obst, key, size);
447 q = obstack_finish (&table->obst);
448 q->entry.size = size;
450 q->chain = CurrentSegment[SegmentIndex];
451 q->entry.hash = hash;
452 CurrentSegment[SegmentIndex] = q;
454 if (loaded (table)) {
455 expand_table(table); /* doesn't affect q */
461 if (action == _pset_hinsert) return &q->entry;
463 if (action == _set_hinsert || action == _set_hinsert0) return &q->entry;
465 return q->entry.dptr;
472 pset_remove (SET *table, const void *key, unsigned hash)
475 Segment *CurrentSegment;
477 pset_cmp_fun cmp = table->cmp;
482 assert (table && !table->iter_tail);
485 /* Find collision chain */
486 h = Hash (table, hash);
487 SegmentIndex = h & (SEGMENT_SIZE-1);
488 CurrentSegment = table->dir[h >> SEGMENT_SIZE_SHIFT];
489 assert (CurrentSegment != NULL);
490 p = &CurrentSegment[SegmentIndex];
492 /* Follow collision chain */
493 while (!EQUAL (cmp, *p, key, size)) {
499 stat_chain_len (table, chain_len);
503 if (q == table->iter_tail) {
504 /* removing current element */
505 table->iter_tail = q->chain;
506 if (!table->iter_tail) {
507 /* go to next segment */
509 if (!iter_step (table))
511 } while (!table->dir[table->iter_i][table->iter_j]);
512 table->iter_tail = table->dir[table->iter_i][table->iter_j];
517 q->chain = table->free_list;
518 table->free_list = q;
521 return q->entry.dptr;
526 (pset_find) (SET *se, const void *key, unsigned hash)
528 return pset_find (se, key, hash);
533 (pset_insert) (SET *se, const void *key, unsigned hash)
535 return pset_insert (se, key, hash);
540 (pset_hinsert) (SET *se, const void *key, unsigned hash)
542 return pset_hinsert (se, key, hash);
548 (set_find) (set *se, const void *key, size_t size, unsigned hash)
550 return set_find (se, key, size, hash);
555 (set_insert) (set *se, const void *key, size_t size, unsigned hash)
557 return set_insert (se, key, size, hash);
562 (set_hinsert) (set *se, const void *key, size_t size, unsigned hash)
564 return set_hinsert (se, key, size, hash);