1/**************************************************************************
2 *
3 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28 /*
29  * Authors:
30  *   Zack Rusin <zack@tungstengraphics.com>
31  */
32
33#include "util/u_debug.h"
34#include "util/u_memory.h"
35
36#include "cso_hash.h"
37
38#define MAX(a, b) ((a > b) ? (a) : (b))
39
40static const int MinNumBits = 4;
41
42static const unsigned char prime_deltas[] = {
43   0,  0,  1,  3,  1,  5,  3,  3,  1,  9,  7,  5,  3,  9, 25,  3,
44   1, 21,  3, 21,  7, 15,  9,  5,  3, 29, 15,  0,  0,  0,  0,  0
45};
46
47static int primeForNumBits(int numBits)
48{
49   return (1 << numBits) + prime_deltas[numBits];
50}
51
52/*
53    Returns the smallest integer n such that
54    primeForNumBits(n) >= hint.
55*/
56static int countBits(int hint)
57{
58   int numBits = 0;
59   int bits = hint;
60
61   while (bits > 1) {
62      bits >>= 1;
63      numBits++;
64   }
65
66   if (numBits >= (int)sizeof(prime_deltas)) {
67      numBits = sizeof(prime_deltas) - 1;
68   } else if (primeForNumBits(numBits) < hint) {
69      ++numBits;
70   }
71   return numBits;
72}
73
74struct cso_node {
75   struct cso_node *next;
76   unsigned key;
77   void *value;
78};
79
80struct cso_hash_data {
81   struct cso_node *fakeNext;
82   struct cso_node **buckets;
83   int size;
84   int nodeSize;
85   short userNumBits;
86   short numBits;
87   int numBuckets;
88};
89
90struct cso_hash {
91   union {
92      struct cso_hash_data *d;
93      struct cso_node      *e;
94   } data;
95};
96
97static void *cso_data_allocate_node(struct cso_hash_data *hash)
98{
99   return MALLOC(hash->nodeSize);
100}
101
102static void cso_free_node(struct cso_node *node)
103{
104   FREE(node);
105}
106
107static struct cso_node *
108cso_hash_create_node(struct cso_hash *hash,
109                      unsigned akey, void *avalue,
110                      struct cso_node **anextNode)
111{
112   struct cso_node *node = cso_data_allocate_node(hash->data.d);
113
114   if (!node)
115      return NULL;
116
117   node->key = akey;
118   node->value = avalue;
119
120   node->next = (struct cso_node*)(*anextNode);
121   *anextNode = node;
122   ++hash->data.d->size;
123   return node;
124}
125
126static void cso_data_rehash(struct cso_hash_data *hash, int hint)
127{
128   if (hint < 0) {
129      hint = countBits(-hint);
130      if (hint < MinNumBits)
131         hint = MinNumBits;
132      hash->userNumBits = (short)hint;
133      while (primeForNumBits(hint) < (hash->size >> 1))
134         ++hint;
135   } else if (hint < MinNumBits) {
136      hint = MinNumBits;
137   }
138
139   if (hash->numBits != hint) {
140      struct cso_node *e = (struct cso_node *)(hash);
141      struct cso_node **oldBuckets = hash->buckets;
142      int oldNumBuckets = hash->numBuckets;
143      int  i = 0;
144
145      hash->numBits = (short)hint;
146      hash->numBuckets = primeForNumBits(hint);
147      hash->buckets = MALLOC(sizeof(struct cso_node*) * hash->numBuckets);
148      for (i = 0; i < hash->numBuckets; ++i)
149         hash->buckets[i] = e;
150
151      for (i = 0; i < oldNumBuckets; ++i) {
152         struct cso_node *firstNode = oldBuckets[i];
153         while (firstNode != e) {
154            unsigned h = firstNode->key;
155            struct cso_node *lastNode = firstNode;
156            struct cso_node *afterLastNode;
157            struct cso_node **beforeFirstNode;
158
159            while (lastNode->next != e && lastNode->next->key == h)
160               lastNode = lastNode->next;
161
162            afterLastNode = lastNode->next;
163            beforeFirstNode = &hash->buckets[h % hash->numBuckets];
164            while (*beforeFirstNode != e)
165               beforeFirstNode = &(*beforeFirstNode)->next;
166            lastNode->next = *beforeFirstNode;
167            *beforeFirstNode = firstNode;
168            firstNode = afterLastNode;
169         }
170      }
171      FREE(oldBuckets);
172   }
173}
174
175static void cso_data_might_grow(struct cso_hash_data *hash)
176{
177   if (hash->size >= hash->numBuckets)
178      cso_data_rehash(hash, hash->numBits + 1);
179}
180
181static void cso_data_has_shrunk(struct cso_hash_data *hash)
182{
183   if (hash->size <= (hash->numBuckets >> 3) &&
184       hash->numBits > hash->userNumBits) {
185      int max = MAX(hash->numBits-2, hash->userNumBits);
186      cso_data_rehash(hash,  max);
187   }
188}
189
190static struct cso_node *cso_data_first_node(struct cso_hash_data *hash)
191{
192   struct cso_node *e = (struct cso_node *)(hash);
193   struct cso_node **bucket = hash->buckets;
194   int n = hash->numBuckets;
195   while (n--) {
196      if (*bucket != e)
197         return *bucket;
198      ++bucket;
199   }
200   return e;
201}
202
203static struct cso_node **cso_hash_find_node(struct cso_hash *hash, unsigned akey)
204{
205   struct cso_node **node;
206
207   if (hash->data.d->numBuckets) {
208      node = (struct cso_node **)(&hash->data.d->buckets[akey % hash->data.d->numBuckets]);
209      assert(*node == hash->data.e || (*node)->next);
210      while (*node != hash->data.e && (*node)->key != akey)
211         node = &(*node)->next;
212   } else {
213      node = (struct cso_node **)((const struct cso_node * const *)(&hash->data.e));
214   }
215   return node;
216}
217
218struct cso_hash_iter cso_hash_insert(struct cso_hash *hash,
219                                       unsigned key, void *data)
220{
221   cso_data_might_grow(hash->data.d);
222
223   {
224      struct cso_node **nextNode = cso_hash_find_node(hash, key);
225      struct cso_node *node = cso_hash_create_node(hash, key, data, nextNode);
226      if (!node) {
227         struct cso_hash_iter null_iter = {hash, 0};
228         return null_iter;
229      }
230
231      {
232         struct cso_hash_iter iter = {hash, node};
233         return iter;
234      }
235   }
236}
237
238struct cso_hash * cso_hash_create(void)
239{
240   struct cso_hash *hash = MALLOC_STRUCT(cso_hash);
241   if (!hash)
242      return NULL;
243
244   hash->data.d = MALLOC_STRUCT(cso_hash_data);
245   if (!hash->data.d) {
246      FREE(hash);
247      return NULL;
248   }
249
250   hash->data.d->fakeNext = 0;
251   hash->data.d->buckets = 0;
252   hash->data.d->size = 0;
253   hash->data.d->nodeSize = sizeof(struct cso_node);
254   hash->data.d->userNumBits = (short)MinNumBits;
255   hash->data.d->numBits = 0;
256   hash->data.d->numBuckets = 0;
257
258   return hash;
259}
260
261void cso_hash_delete(struct cso_hash *hash)
262{
263   struct cso_node *e_for_x = (struct cso_node *)(hash->data.d);
264   struct cso_node **bucket = (struct cso_node **)(hash->data.d->buckets);
265   int n = hash->data.d->numBuckets;
266   while (n--) {
267      struct cso_node *cur = *bucket++;
268      while (cur != e_for_x) {
269         struct cso_node *next = cur->next;
270         cso_free_node(cur);
271         cur = next;
272      }
273   }
274   FREE(hash->data.d->buckets);
275   FREE(hash->data.d);
276   FREE(hash);
277}
278
279struct cso_hash_iter cso_hash_find(struct cso_hash *hash,
280                                     unsigned key)
281{
282   struct cso_node **nextNode = cso_hash_find_node(hash, key);
283   struct cso_hash_iter iter = {hash, *nextNode};
284   return iter;
285}
286
287unsigned cso_hash_iter_key(struct cso_hash_iter iter)
288{
289   if (!iter.node || iter.hash->data.e == iter.node)
290      return 0;
291   return iter.node->key;
292}
293
294void * cso_hash_iter_data(struct cso_hash_iter iter)
295{
296   if (!iter.node || iter.hash->data.e == iter.node)
297      return 0;
298   return iter.node->value;
299}
300
301static struct cso_node *cso_hash_data_next(struct cso_node *node)
302{
303   union {
304      struct cso_node *next;
305      struct cso_node *e;
306      struct cso_hash_data *d;
307   } a;
308   int start;
309   struct cso_node **bucket;
310   int n;
311
312   a.next = node->next;
313   if (!a.next) {
314      debug_printf("iterating beyond the last element\n");
315      return 0;
316   }
317   if (a.next->next)
318      return a.next;
319
320   start = (node->key % a.d->numBuckets) + 1;
321   bucket = a.d->buckets + start;
322   n = a.d->numBuckets - start;
323   while (n--) {
324      if (*bucket != a.e)
325         return *bucket;
326      ++bucket;
327   }
328   return a.e;
329}
330
331
332static struct cso_node *cso_hash_data_prev(struct cso_node *node)
333{
334   union {
335      struct cso_node *e;
336      struct cso_hash_data *d;
337   } a;
338   int start;
339   struct cso_node *sentinel;
340   struct cso_node **bucket;
341
342   a.e = node;
343   while (a.e->next)
344      a.e = a.e->next;
345
346   if (node == a.e)
347      start = a.d->numBuckets - 1;
348   else
349      start = node->key % a.d->numBuckets;
350
351   sentinel = node;
352   bucket = a.d->buckets + start;
353   while (start >= 0) {
354      if (*bucket != sentinel) {
355         struct cso_node *prev = *bucket;
356         while (prev->next != sentinel)
357            prev = prev->next;
358         return prev;
359      }
360
361      sentinel = a.e;
362      --bucket;
363      --start;
364   }
365   debug_printf("iterating backward beyond first element\n");
366   return a.e;
367}
368
369struct cso_hash_iter cso_hash_iter_next(struct cso_hash_iter iter)
370{
371   struct cso_hash_iter next = {iter.hash, cso_hash_data_next(iter.node)};
372   return next;
373}
374
375int cso_hash_iter_is_null(struct cso_hash_iter iter)
376{
377   if (!iter.node || iter.node == iter.hash->data.e)
378      return 1;
379   return 0;
380}
381
382void * cso_hash_take(struct cso_hash *hash,
383                      unsigned akey)
384{
385   struct cso_node **node = cso_hash_find_node(hash, akey);
386   if (*node != hash->data.e) {
387      void *t = (*node)->value;
388      struct cso_node *next = (*node)->next;
389      cso_free_node(*node);
390      *node = next;
391      --hash->data.d->size;
392      cso_data_has_shrunk(hash->data.d);
393      return t;
394   }
395   return 0;
396}
397
398struct cso_hash_iter cso_hash_iter_prev(struct cso_hash_iter iter)
399{
400   struct cso_hash_iter prev = {iter.hash,
401                                 cso_hash_data_prev(iter.node)};
402   return prev;
403}
404
405struct cso_hash_iter cso_hash_first_node(struct cso_hash *hash)
406{
407   struct cso_hash_iter iter = {hash, cso_data_first_node(hash->data.d)};
408   return iter;
409}
410
411int cso_hash_size(struct cso_hash *hash)
412{
413   return hash->data.d->size;
414}
415
416struct cso_hash_iter cso_hash_erase(struct cso_hash *hash, struct cso_hash_iter iter)
417{
418   struct cso_hash_iter ret = iter;
419   struct cso_node *node = iter.node;
420   struct cso_node **node_ptr;
421
422   if (node == hash->data.e)
423      return iter;
424
425   ret = cso_hash_iter_next(ret);
426   node_ptr = (struct cso_node**)(&hash->data.d->buckets[node->key % hash->data.d->numBuckets]);
427   while (*node_ptr != node)
428      node_ptr = &(*node_ptr)->next;
429   *node_ptr = node->next;
430   cso_free_node(node);
431   --hash->data.d->size;
432   return ret;
433}
434
435boolean cso_hash_contains(struct cso_hash *hash, unsigned key)
436{
437   struct cso_node **node = cso_hash_find_node(hash, key);
438   return (*node != hash->data.e);
439}
440