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)))
71 #define TOBSTACK_ID MANGLEP(tag)
75 #define SEGMENT_SIZE_SHIFT 8
76 #define SEGMENT_SIZE (1 << SEGMENT_SIZE_SHIFT)
77 #define DIRECTORY_SIZE_SHIFT 8
78 #define DIRECTORY_SIZE (1 << DIRECTORY_SIZE_SHIFT)
79 #define MAX_LOAD_FACTOR 4
82 typedef struct element {
83 struct element *chain; /* for chaining Elements */
84 MANGLEP (entry) entry;
89 short p; /* Next bucket to be split */
90 short maxp; /* upper bound on p during expansion */
91 int nkey; /* current # keys */
92 short nseg; /* current # segments */
93 Segment *dir[DIRECTORY_SIZE];
94 MANGLEP(cmp_fun) cmp; /* function comparing entries */
96 Element *iter_tail; /* non-NULL while iterating over elts */
98 Element *free_list; /* list of free Elements */
100 struct obstack obst; /* obstack for allocation all data */
102 int naccess, ncollision, ndups;
114 MANGLEP(stats) (SET *table)
118 Element *q = table->free_list;
119 while (q) { q = q->chain; ++nfree; }
121 printf (" accesses collisions keys duplicates longest wasted\n%12d%12d%12d%12d%12d%12d\n",
122 table->naccess, table->ncollision, table->nkey, table->ndups, table->max_chain_len, nfree);
126 stat_chain_len (SET *table, int chain_len)
128 table->ncollision += chain_len;
129 if (table->max_chain_len < chain_len) table->max_chain_len = chain_len;
132 # define stat_access(table) (++(table)->naccess)
133 # define stat_dup(table) (++(table)->ndups)
137 # define stat_chain_len(table, chain_len) ((void)0)
138 # define stat_access(table) ((void)0)
139 # define stat_dup(table) ((void)0)
145 const char *MANGLEP(tag);
149 MANGLEP(describe) (SET *table)
155 printf ("p=%d maxp=%d nkey=%d nseg=%d\n",
156 table->p, table->maxp, table->nkey, table->nseg);
157 for (i = 0; i < table->nseg; i++) {
159 for (j = 0; j < SEGMENT_SIZE; j++) {
163 if (collide) printf ("<%3d>", collide);
164 else printf ("table");
165 printf ("[%d][%3d]: %u %p\n", i, j, ptr->entry.hash, ptr->entry.dptr);
177 (PMANGLE(new)) (MANGLEP(cmp_fun) cmp, int nslots)
180 SET *table = xmalloc (sizeof (SET));
182 /* Adjust nslots up to next power of 2, minimum SEGMENT_SIZE */
183 assert (nslots >= 0);
184 for (i = SEGMENT_SIZE; i < nslots; i <<= 1) assert (i < (i << 1));
185 nslots = i >> SEGMENT_SIZE_SHIFT;
187 table->nseg = table->p = table->nkey = 0;
188 table->maxp = nslots << SEGMENT_SIZE_SHIFT;
190 table->iter_tail = NULL;
192 table->free_list = NULL;
194 obstack_init (&table->obst);
197 for (i = 0; i < nslots; ++i) {
198 table->dir[i] = (Segment *)obstack_alloc (&table->obst,
199 sizeof (Segment) * SEGMENT_SIZE);
201 memset(table->dir[i], 0, sizeof (Segment) * SEGMENT_SIZE);
206 table->naccess = table->ncollision = table->ndups = 0;
207 table->max_chain_len = 0;
210 table->tag = MANGLEP(tag);
217 PMANGLE(del) (SET *table)
220 MANGLEP(tag) = table->tag;
222 obstack_free (&table->obst, NULL);
227 MANGLEP(count) (SET *table)
233 * do one iteration step, return 1
234 * if still data in the set, 0 else
237 iter_step (SET *table)
239 if (++table->iter_j >= SEGMENT_SIZE) {
241 if (++table->iter_i >= table->nseg) {
250 * finds the first entry in the table
253 MANGLEP(first) (SET *table)
255 assert (!table->iter_tail);
258 while (!table->dir[table->iter_i][table->iter_j]) {
259 if (!iter_step (table)) return NULL;
261 table->iter_tail = table->dir[table->iter_i][table->iter_j];
262 assert (table->iter_tail->entry.dptr);
263 return table->iter_tail->entry.dptr;
267 * returns next entry in the table
270 MANGLEP(next) (SET *table)
272 if (!table->iter_tail)
275 /* follow collision chain */
276 table->iter_tail = table->iter_tail->chain;
277 if (!table->iter_tail) {
278 /* go to next segment */
280 if (!iter_step (table)) return NULL;
281 } while (!table->dir[table->iter_i][table->iter_j]);
282 table->iter_tail = table->dir[table->iter_i][table->iter_j];
284 assert (table->iter_tail->entry.dptr);
285 return table->iter_tail->entry.dptr;
289 MANGLEP(break) (SET *table)
291 table->iter_tail = NULL;
295 * limit the hash value
297 static INLINE unsigned
298 Hash (SET *table, unsigned h)
302 address = h & (table->maxp - 1); /* h % table->maxp */
303 if (address < (unsigned)table->p)
304 address = h & ((table->maxp << 1) - 1); /* h % (2*table->maxp) */
309 * returns non-zero if the number of elements in
310 * the set is greater then number of segments * MAX_LOAD_FACTOR
315 return ( ++table->nkey
316 > (table->nseg << SEGMENT_SIZE_SHIFT) * MAX_LOAD_FACTOR);
320 * expand the hash-table: the algorithm is split, so on every
321 * insert, only ONE segment is rehashed!
323 * table->p contains the current segment to split
324 * after all segments were split, table->p is set to zero and
325 * table->maxp is duplicated.
328 expand_table (SET *table)
331 int OldSegmentIndex, NewSegmentIndex;
332 int OldSegmentDir, NewSegmentDir;
339 if (table->maxp + table->p < (DIRECTORY_SIZE << SEGMENT_SIZE_SHIFT)) {
340 /* Locate the bucket to be split */
341 OldSegmentDir = table->p >> SEGMENT_SIZE_SHIFT;
342 OldSegment = table->dir[OldSegmentDir];
343 OldSegmentIndex = table->p & (SEGMENT_SIZE-1);
345 /* Expand address space; if necessary create a new segment */
346 NewAddress = table->maxp + table->p;
347 NewSegmentDir = NewAddress >> SEGMENT_SIZE_SHIFT;
348 NewSegmentIndex = NewAddress & (SEGMENT_SIZE-1);
349 if (NewSegmentIndex == 0) {
350 table->dir[NewSegmentDir] =
351 (Segment *)obstack_alloc (&table->obst,
352 sizeof(Segment) * SEGMENT_SIZE);
353 memset(table->dir[NewSegmentDir], 0, sizeof(Segment) * SEGMENT_SIZE);
356 NewSegment = table->dir[NewSegmentDir];
358 /* Adjust state variables */
360 if (table->p == table->maxp) {
361 table->maxp <<= 1; /* table->maxp *= 2 */
365 /* Relocate records to the new bucket */
366 Previous = &OldSegment[OldSegmentIndex];
368 LastOfNew = &NewSegment[NewSegmentIndex];
370 while (Current != NULL) {
371 if (Hash (table, Current->entry.hash) == NewAddress) {
372 /* move to new chain */
373 *LastOfNew = Current;
374 *Previous = Current->chain;
375 LastOfNew = &Current->chain;
376 Current = Current->chain;
379 /* leave on old chain */
380 Previous = &Current->chain;
381 Current = Current->chain;
389 MANGLE(_,_search) (SET *table,
395 MANGLE(_,_action) action)
398 Segment *CurrentSegment;
400 MANGLEP(cmp_fun) cmp = table->cmp;
405 assert (!table->iter_tail);
408 MANGLEP(tag) = table->tag;
412 /* Find collision chain */
413 h = Hash (table, hash);
414 SegmentIndex = h & (SEGMENT_SIZE-1);
415 CurrentSegment = table->dir[h >> SEGMENT_SIZE_SHIFT];
416 assert (CurrentSegment != NULL);
417 q = CurrentSegment[SegmentIndex];
419 /* Follow collision chain */
420 while (q && !EQUAL (cmp, q, key, size)) {
425 stat_chain_len (table, chain_len);
427 if (!q && (action != MANGLE(_,_find))) { /* not found, insert */
428 if (CurrentSegment[SegmentIndex]) stat_dup (table);
431 if (table->free_list) {
432 q = table->free_list;
433 table->free_list = table->free_list->chain;
435 q = obstack_alloc (&table->obst, sizeof (Element));
437 q->entry.dptr = (void *)key;
439 obstack_blank (&table->obst, offsetof (Element, entry.dptr));
440 if (action == _set_hinsert0)
441 obstack_grow0 (&table->obst, key, size);
443 obstack_grow (&table->obst, key, size);
444 q = obstack_finish (&table->obst);
445 q->entry.size = size;
447 q->chain = CurrentSegment[SegmentIndex];
448 q->entry.hash = hash;
449 CurrentSegment[SegmentIndex] = q;
451 if (loaded (table)) {
452 expand_table(table); /* doesn't affect q */
458 if (action == _pset_hinsert) return &q->entry;
460 if (action == _set_hinsert || action == _set_hinsert0) return &q->entry;
462 return q->entry.dptr;
469 pset_remove (SET *table, const void *key, unsigned hash)
472 Segment *CurrentSegment;
474 pset_cmp_fun cmp = table->cmp;
479 assert (table && !table->iter_tail);
482 /* Find collision chain */
483 h = Hash (table, hash);
484 SegmentIndex = h & (SEGMENT_SIZE-1);
485 CurrentSegment = table->dir[h >> SEGMENT_SIZE_SHIFT];
486 assert (CurrentSegment != NULL);
487 p = &CurrentSegment[SegmentIndex];
489 /* Follow collision chain */
490 while (!EQUAL (cmp, *p, key, size)) {
496 stat_chain_len (table, chain_len);
500 if (q == table->iter_tail) {
501 /* removing current element */
502 table->iter_tail = q->chain;
503 if (!table->iter_tail) {
504 /* go to next segment */
506 if (!iter_step (table))
508 } while (!table->dir[table->iter_i][table->iter_j]);
509 table->iter_tail = table->dir[table->iter_i][table->iter_j];
514 q->chain = table->free_list;
515 table->free_list = q;
518 return q->entry.dptr;
523 (pset_find) (SET *se, const void *key, unsigned hash)
525 return pset_find (se, key, hash);
530 (pset_insert) (SET *se, const void *key, unsigned hash)
532 return pset_insert (se, key, hash);
537 (pset_hinsert) (SET *se, const void *key, unsigned hash)
539 return pset_hinsert (se, key, hash);
545 (set_find) (set *se, const void *key, size_t size, unsigned hash)
547 return set_find (se, key, size, hash);
552 (set_insert) (set *se, const void *key, size_t size, unsigned hash)
554 return set_insert (se, key, size, hash);
559 (set_hinsert) (set *se, const void *key, size_t size, unsigned hash)
561 return set_hinsert (se, key, size, hash);