src/gallium/auxiliary/cso_cache/cso_hash.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2007 VMware, Inc.
   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 VMWARE 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 <zackr@vmware.com>
  31   */
  32
  33 #include "util/u_debug.h"
  34 #include "util/u_memory.h"
  35
  36 #include "cso_hash.h"
  37
  38 #ifndef MAX
  39 #define MAX(a, b) ((a > b) ? (a) : (b))
  40 #endif
  41
  42 static const int MinNumBits = 4;
  43
  44 static const unsigned char prime_deltas[] = {
  45    0,  0,  1,  3,  1,  5,  3,  3,  1,  9,  7,  5,  3,  9, 25,  3,
  46    1, 21,  3, 21,  7, 15,  9,  5,  3, 29, 15,  0,  0,  0,  0,  0
  47 };
  48
  49 static int primeForNumBits(int numBits)
  50 {
  51    return (1 << numBits) + prime_deltas[numBits];
  52 }
  53
  54 /*
  55     Returns the smallest integer n such that
  56     primeForNumBits(n) >= hint.
  57 */
  58 static int countBits(int hint)
  59 {
  60    int numBits = 0;
  61    int bits = hint;
  62
  63    while (bits > 1) {
  64       bits >>= 1;
  65       numBits++;
  66    }
  67
  68    if (numBits >= (int)sizeof(prime_deltas)) {
  69       numBits = sizeof(prime_deltas) - 1;
  70    } else if (primeForNumBits(numBits) < hint) {
  71       ++numBits;
  72    }
  73    return numBits;
  74 }
  75
  76 static struct cso_node *
  77 cso_hash_create_node(struct cso_hash *hash,
  78                      unsigned akey, void *avalue,
  79                      struct cso_node **anextNode)
  80 {
  81    struct cso_node *node = MALLOC(sizeof(struct cso_node));
  82
  83    if (!node)
  84       return NULL;
  85
  86    node->key = akey;
  87    node->value = avalue;
  88
  89    node->next = *anextNode;
  90    *anextNode = node;
  91    ++hash->size;
  92    return node;
  93 }
  94
  95 static void cso_data_rehash(struct cso_hash *hash, int hint)
  96 {
  97    if (hint < 0) {
  98       hint = countBits(-hint);
  99       if (hint < MinNumBits)
 100          hint = MinNumBits;
 101       hash->userNumBits = (short)hint;
 102       while (primeForNumBits(hint) < (hash->size >> 1))
 103          ++hint;
 104    } else if (hint < MinNumBits) {
 105       hint = MinNumBits;
 106    }
 107
 108    if (hash->numBits != hint) {
 109       struct cso_node *e = (struct cso_node *)hash;
 110       struct cso_node **oldBuckets = hash->buckets;
 111       int oldNumBuckets = hash->numBuckets;
 112       int  i = 0;
 113
 114       hash->numBits = (short)hint;
 115       hash->numBuckets = primeForNumBits(hint);
 116       hash->buckets = MALLOC(sizeof(struct cso_node*) * hash->numBuckets);
 117       for (i = 0; i < hash->numBuckets; ++i)
 118          hash->buckets[i] = e;
 119
 120       for (i = 0; i < oldNumBuckets; ++i) {
 121          struct cso_node *firstNode = oldBuckets[i];
 122          while (firstNode != e) {
 123             unsigned h = firstNode->key;
 124             struct cso_node *lastNode = firstNode;
 125             struct cso_node *afterLastNode;
 126             struct cso_node **beforeFirstNode;
 127
 128             while (lastNode->next != e && lastNode->next->key == h)
 129                lastNode = lastNode->next;
 130
 131             afterLastNode = lastNode->next;
 132             beforeFirstNode = &hash->buckets[h % hash->numBuckets];
 133             while (*beforeFirstNode != e)
 134                beforeFirstNode = &(*beforeFirstNode)->next;
 135             lastNode->next = *beforeFirstNode;
 136             *beforeFirstNode = firstNode;
 137             firstNode = afterLastNode;
 138          }
 139       }
 140       FREE(oldBuckets);
 141    }
 142 }
 143
 144 static void cso_data_might_grow(struct cso_hash *hash)
 145 {
 146    if (hash->size >= hash->numBuckets)
 147       cso_data_rehash(hash, hash->numBits + 1);
 148 }
 149
 150 static void cso_data_has_shrunk(struct cso_hash *hash)
 151 {
 152    if (hash->size <= (hash->numBuckets >> 3) &&
 153        hash->numBits > hash->userNumBits) {
 154       int max = MAX(hash->numBits-2, hash->userNumBits);
 155       cso_data_rehash(hash,  max);
 156    }
 157 }
 158
 159 static struct cso_node *cso_data_first_node(struct cso_hash *hash)
 160 {
 161    struct cso_node *e = (struct cso_node *)hash;
 162    struct cso_node **bucket = hash->buckets;
 163    int n = hash->numBuckets;
 164
 165    while (n--) {
 166       if (*bucket != e)
 167          return *bucket;
 168       ++bucket;
 169    }
 170    return e;
 171 }
 172
 173 struct cso_hash_iter cso_hash_insert(struct cso_hash *hash,
 174                                      unsigned key, void *data)
 175 {
 176    cso_data_might_grow(hash);
 177
 178    struct cso_node **nextNode = cso_hash_find_node(hash, key);
 179    struct cso_node *node = cso_hash_create_node(hash, key, data, nextNode);
 180    if (!node) {
 181       struct cso_hash_iter null_iter = {hash, 0};
 182       return null_iter;
 183    }
 184
 185    struct cso_hash_iter iter = {hash, node};
 186    return iter;
 187 }
 188
 189 void cso_hash_init(struct cso_hash *hash)
 190 {
 191    hash->fakeNext = 0;
 192    hash->buckets = 0;
 193    hash->size = 0;
 194    hash->userNumBits = (short)MinNumBits;
 195    hash->numBits = 0;
 196    hash->numBuckets = 0;
 197    hash->end = (struct cso_node*)hash;
 198 }
 199
 200 void cso_hash_deinit(struct cso_hash *hash)
 201 {
 202    struct cso_node *e_for_x = hash->end;
 203    struct cso_node **bucket = hash->buckets;
 204    int n = hash->numBuckets;
 205
 206    while (n--) {
 207       struct cso_node *cur = *bucket++;
 208       while (cur != e_for_x) {
 209          struct cso_node *next = cur->next;
 210          FREE(cur);
 211          cur = next;
 212       }
 213    }
 214    FREE(hash->buckets);
 215 }
 216
 217 unsigned cso_hash_iter_key(struct cso_hash_iter iter)
 218 {
 219    if (!iter.node || iter.hash->end == iter.node)
 220       return 0;
 221    return iter.node->key;
 222 }
 223
 224 struct cso_node *cso_hash_data_next(struct cso_node *node)
 225 {
 226    union {
 227       struct cso_node *next;
 228       struct cso_node *e;
 229       struct cso_hash *d;
 230    } a;
 231    int start;
 232    struct cso_node **bucket;
 233    int n;
 234
 235    a.next = node->next;
 236    if (!a.next) {
 237       debug_printf("iterating beyond the last element\n");
 238       return NULL;
 239    }
 240    if (a.next->next)
 241       return a.next;
 242
 243    start = (node->key % a.d->numBuckets) + 1;
 244    bucket = a.d->buckets + start;
 245    n = a.d->numBuckets - start;
 246    while (n--) {
 247       if (*bucket != a.e)
 248          return *bucket;
 249       ++bucket;
 250    }
 251    return a.e;
 252 }
 253
 254
 255 static struct cso_node *cso_hash_data_prev(struct cso_node *node)
 256 {
 257    union {
 258       struct cso_node *e;
 259       struct cso_hash *d;
 260    } a;
 261    int start;
 262    struct cso_node *sentinel;
 263    struct cso_node **bucket;
 264
 265    a.e = node;
 266    while (a.e->next)
 267       a.e = a.e->next;
 268
 269    if (node == a.e)
 270       start = a.d->numBuckets - 1;
 271    else
 272       start = node->key % a.d->numBuckets;
 273
 274    sentinel = node;
 275    bucket = a.d->buckets + start;
 276    while (start >= 0) {
 277       if (*bucket != sentinel) {
 278          struct cso_node *prev = *bucket;
 279          while (prev->next != sentinel)
 280             prev = prev->next;
 281          return prev;
 282       }
 283
 284       sentinel = a.e;
 285       --bucket;
 286       --start;
 287    }
 288    debug_printf("iterating backward beyond first element\n");
 289    return a.e;
 290 }
 291
 292 void *cso_hash_take(struct cso_hash *hash, unsigned akey)
 293 {
 294    struct cso_node **node = cso_hash_find_node(hash, akey);
 295
 296    if (*node != hash->end) {
 297       void *t = (*node)->value;
 298       struct cso_node *next = (*node)->next;
 299       FREE(*node);
 300       *node = next;
 301       --hash->size;
 302       cso_data_has_shrunk(hash);
 303       return t;
 304    }
 305    return NULL;
 306 }
 307
 308 struct cso_hash_iter cso_hash_iter_prev(struct cso_hash_iter iter)
 309 {
 310    struct cso_hash_iter prev = {iter.hash,
 311                                 cso_hash_data_prev(iter.node)};
 312    return prev;
 313 }
 314
 315 struct cso_hash_iter cso_hash_first_node(struct cso_hash *hash)
 316 {
 317    struct cso_hash_iter iter = {hash, cso_data_first_node(hash)};
 318    return iter;
 319 }
 320
 321 int cso_hash_size(struct cso_hash *hash)
 322 {
 323    return hash->size;
 324 }
 325
 326 struct cso_hash_iter cso_hash_erase(struct cso_hash *hash, struct cso_hash_iter iter)
 327 {
 328    struct cso_hash_iter ret = iter;
 329    struct cso_node *node = iter.node;
 330    struct cso_node **node_ptr;
 331
 332    if (node == hash->end)
 333       return iter;
 334
 335    ret = cso_hash_iter_next(ret);
 336    node_ptr = &hash->buckets[node->key % hash->numBuckets];
 337    while (*node_ptr != node)
 338       node_ptr = &(*node_ptr)->next;
 339    *node_ptr = node->next;
 340    FREE(node);
 341    --hash->size;
 342    return ret;
 343 }
 344
 345 bool cso_hash_contains(struct cso_hash *hash, unsigned key)
 346 {
 347    struct cso_node **node = cso_hash_find_node(hash, key);
 348    return *node != hash->end;
 349 }