src/mesa/drivers/dri/dri_client/xf86drmSL.c

   1 /* xf86drmSL.c -- Skip list support
   2  * Created: Mon May 10 09:28:13 1999 by faith@precisioninsight.com
   3  *
   4  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
   5  * All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the "Software"),
   9  * to deal in the Software without restriction, including without limitation
  10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11  * and/or sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the next
  15  * paragraph) shall be included in all copies or substantial portions of the
  16  * Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  21  * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  22  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  23  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  24  * DEALINGS IN THE SOFTWARE.
  25  *
  26  * Authors: Rickard E. (Rik) Faith <faith@valinux.com>
  27  *
  28  * $XFree86: xc/programs/Xserver/hw/xfree86/os-support/linux/drm/xf86drmSL.c,v 1.3 2000/06/17 00:03:34 martin Exp $
  29  *
  30  * DESCRIPTION
  31  *
  32  * This file contains a straightforward skip list implementation.n
  33  *
  34  * FUTURE ENHANCEMENTS
  35  *
  36  * REFERENCES
  37  *
  38  * [Pugh90] William Pugh.  Skip Lists: A Probabilistic Alternative to
  39  * Balanced Trees. CACM 33(6), June 1990, pp. 668-676.
  40  *
  41  */
  42
  43 #define SL_MAIN 0
  44
  45 #if SL_MAIN
  46 # include <stdio.h>
  47 # include <stdlib.h>
  48 #  include <sys/time.h>
  49 #else
  50 # include "xf86drm.h"
  51 # ifdef XFree86LOADER
  52 #  include "xf86.h"
  53 #  include "xf86_ansic.h"
  54 # else
  55 #  include <stdio.h>
  56 #  include <stdlib.h>
  57 # endif
  58 #endif
  59
  60 #define N(x)  drm##x
  61
  62 #define SL_LIST_MAGIC  0xfacade00LU
  63 #define SL_ENTRY_MAGIC 0x00fab1edLU
  64 #define SL_FREED_MAGIC 0xdecea5edLU
  65 #define SL_MAX_LEVEL   16
  66 #define SL_DEBUG       0
  67 #define SL_RANDOM_SEED 0xc01055a1LU
  68
  69 #if SL_MAIN
  70 #define SL_ALLOC malloc
  71 #define SL_FREE  free
  72 #define SL_RANDOM_DECL        static int state = 0;
  73 #define SL_RANDOM_INIT(seed)  if (!state) { srandom(seed); ++state; }
  74 #define SL_RANDOM             random()
  75 #else
  76 #define SL_ALLOC drmMalloc
  77 #define SL_FREE  drmFree
  78 #define SL_RANDOM_DECL        static void *state = NULL
  79 #define SL_RANDOM_INIT(seed)  if (!state) state = drmRandomCreate(seed)
  80 #define SL_RANDOM             drmRandom(state)
  81
  82 #endif
  83
  84 typedef struct SLEntry {
  85     unsigned long     magic;       /* SL_ENTRY_MAGIC */
  86     unsigned long     key;
  87     void              *value;
  88     int               levels;
  89     struct SLEntry    *forward[1]; /* variable sized array */
  90 } SLEntry, *SLEntryPtr;
  91
  92 typedef struct SkipList {
  93     unsigned long    magic;     /* SL_LIST_MAGIC */
  94     int              level;
  95     int              count;
  96     SLEntryPtr       head;
  97     SLEntryPtr       p0;        /* Position for iteration */
  98 } SkipList, *SkipListPtr;
  99
 100 #if SL_MAIN
 101 extern void *N(SLCreate)(void);
 102 extern int  N(SLDestroy)(void *l);
 103 extern int  N(SLLookup)(void *l, unsigned long key, void **value);
 104 extern int  N(SLInsert)(void *l, unsigned long key, void *value);
 105 extern int  N(SLDelete)(void *l, unsigned long key);
 106 extern int  N(SLNext)(void *l, unsigned long *key, void **value);
 107 extern int  N(SLFirst)(void *l, unsigned long *key, void **value);
 108 extern void N(SLDump)(void *l);
 109 extern int  N(SLLookupNeighbors)(void *l, unsigned long key,
 110                                  unsigned long *prev_key, void **prev_value,
 111                                  unsigned long *next_key, void **next_value);
 112 #endif
 113
 114 static SLEntryPtr SLCreateEntry(int max_level, unsigned long key, void *value)
 115 {
 116     SLEntryPtr entry;
 117
 118     if (max_level < 0 || max_level > SL_MAX_LEVEL) max_level = SL_MAX_LEVEL;
 119
 120     entry         = SL_ALLOC(sizeof(*entry)
 121                              + (max_level + 1) * sizeof(entry->forward[0]));
 122     if (!entry) return NULL;
 123     entry->magic  = SL_ENTRY_MAGIC;
 124     entry->key    = key;
 125     entry->value  = value;
 126     entry->levels = max_level + 1;
 127
 128     return entry;
 129 }
 130
 131 static int SLRandomLevel(void)
 132 {
 133     int level = 1;
 134     SL_RANDOM_DECL;
 135
 136     SL_RANDOM_INIT(SL_RANDOM_SEED);
 137
 138     while ((SL_RANDOM & 0x01) && level < SL_MAX_LEVEL) ++level;
 139     return level;
 140 }
 141
 142 void *N(SLCreate)(void)
 143 {
 144     SkipListPtr  list;
 145     int          i;
 146
 147     list           = SL_ALLOC(sizeof(*list));
 148     if (!list) return NULL;
 149     list->magic    = SL_LIST_MAGIC;
 150     list->level    = 0;
 151     list->head     = SLCreateEntry(SL_MAX_LEVEL, 0, NULL);
 152     list->count    = 0;
 153
 154     for (i = 0; i <= SL_MAX_LEVEL; i++) list->head->forward[i] = NULL;
 155
 156     return list;
 157 }
 158
 159 int N(SLDestroy)(void *l)
 160 {
 161     SkipListPtr   list  = (SkipListPtr)l;
 162     SLEntryPtr    entry;
 163     SLEntryPtr    next;
 164
 165     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */
 166
 167     for (entry = list->head; entry; entry = next) {
 168         if (entry->magic != SL_ENTRY_MAGIC) return -1; /* Bad magic */
 169         next         = entry->forward[0];
 170         entry->magic = SL_FREED_MAGIC;
 171         SL_FREE(entry);
 172     }
 173
 174     list->magic = SL_FREED_MAGIC;
 175     SL_FREE(list);
 176     return 0;
 177 }
 178
 179 static SLEntryPtr SLLocate(void *l, unsigned long key, SLEntryPtr *update)
 180 {
 181     SkipListPtr   list  = (SkipListPtr)l;
 182     SLEntryPtr    entry;
 183     int           i;
 184
 185     if (list->magic != SL_LIST_MAGIC) return NULL;
 186
 187     for (i = list->level, entry = list->head; i >= 0; i--) {
 188         while (entry->forward[i] && entry->forward[i]->key < key)
 189             entry = entry->forward[i];
 190         update[i] = entry;
 191     }
 192
 193     return entry->forward[0];
 194 }
 195
 196 int N(SLInsert)(void *l, unsigned long key, void *value)
 197 {
 198     SkipListPtr   list  = (SkipListPtr)l;
 199     SLEntryPtr    entry;
 200     SLEntryPtr    update[SL_MAX_LEVEL + 1];
 201     int           level;
 202     int           i;
 203
 204     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */
 205
 206     entry = SLLocate(list, key, update);
 207
 208     if (entry && entry->key == key) return 1; /* Already in list */
 209
 210
 211     level = SLRandomLevel();
 212     if (level > list->level) {
 213         level = ++list->level;
 214         update[level] = list->head;
 215     }
 216
 217     entry = SLCreateEntry(level, key, value);
 218
 219                                 /* Fix up forward pointers */
 220     for (i = 0; i <= level; i++) {
 221         entry->forward[i]     = update[i]->forward[i];
 222         update[i]->forward[i] = entry;
 223     }
 224
 225     ++list->count;
 226     return 0;                   /* Added to table */
 227 }
 228
 229 int N(SLDelete)(void *l, unsigned long key)
 230 {
 231     SkipListPtr   list = (SkipListPtr)l;
 232     SLEntryPtr    update[SL_MAX_LEVEL + 1];
 233     SLEntryPtr    entry;
 234     int           i;
 235
 236     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */
 237
 238     entry = SLLocate(list, key, update);
 239
 240     if (!entry || entry->key != key) return 1; /* Not found */
 241
 242                                 /* Fix up forward pointers */
 243     for (i = 0; i <= list->level; i++) {
 244         if (update[i]->forward[i] == entry)
 245             update[i]->forward[i] = entry->forward[i];
 246     }
 247
 248     entry->magic = SL_FREED_MAGIC;
 249     SL_FREE(entry);
 250
 251     while (list->level && !list->head->forward[list->level]) --list->level;
 252     --list->count;
 253     return 0;
 254 }
 255
 256 int N(SLLookup)(void *l, unsigned long key, void **value)
 257 {
 258     SkipListPtr   list = (SkipListPtr)l;
 259     SLEntryPtr    update[SL_MAX_LEVEL + 1];
 260     SLEntryPtr    entry;
 261
 262     entry = SLLocate(list, key, update);
 263
 264     if (entry && entry->key == key) {
 265         *value = entry;
 266         return 0;
 267     }
 268     *value = NULL;
 269     return -1;
 270 }
 271
 272 int N(SLLookupNeighbors)(void *l, unsigned long key,
 273                          unsigned long *prev_key, void **prev_value,
 274                          unsigned long *next_key, void **next_value)
 275 {
 276     SkipListPtr   list = (SkipListPtr)l;
 277     SLEntryPtr    update[SL_MAX_LEVEL + 1];
 278     SLEntryPtr    entry;
 279     int           retcode = 0;
 280
 281     entry = SLLocate(list, key, update);
 282
 283     *prev_key   = *next_key   = key;
 284     *prev_value = *next_value = NULL;
 285
 286     if (update[0]) {
 287         *prev_key   = update[0]->key;
 288         *prev_value = update[0]->value;
 289         ++retcode;
 290         if (update[0]->forward[0]) {
 291             *next_key   = update[0]->forward[0]->key;
 292             *next_value = update[0]->forward[0]->value;
 293             ++retcode;
 294         }
 295     }
 296     return retcode;
 297 }
 298
 299 int N(SLNext)(void *l, unsigned long *key, void **value)
 300 {
 301     SkipListPtr   list = (SkipListPtr)l;
 302     SLEntryPtr    entry;
 303
 304     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */
 305
 306     entry    = list->p0;
 307
 308     if (entry) {
 309         list->p0 = entry->forward[0];
 310         *key     = entry->key;
 311         *value   = entry->value;
 312         return 1;
 313     }
 314     list->p0 = NULL;
 315     return 0;
 316 }
 317
 318 int N(SLFirst)(void *l, unsigned long *key, void **value)
 319 {
 320     SkipListPtr   list = (SkipListPtr)l;
 321
 322     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */
 323
 324     list->p0 = list->head->forward[0];
 325     return N(SLNext)(list, key, value);
 326 }
 327
 328 /* Dump internal data structures for debugging. */
 329 void N(SLDump)(void *l)
 330 {
 331     SkipListPtr   list = (SkipListPtr)l;
 332     SLEntryPtr    entry;
 333     int           i;
 334
 335     if (list->magic != SL_LIST_MAGIC) {
 336         printf("Bad magic: 0x%08lx (expected 0x%08lx)\n",
 337                list->magic, SL_LIST_MAGIC);
 338         return;
 339     }
 340
 341     printf("Level = %d, count = %d\n", list->level, list->count);
 342     for (entry = list->head; entry; entry = entry->forward[0]) {
 343         if (entry->magic != SL_ENTRY_MAGIC) {
 344             printf("Bad magic: 0x%08lx (expected 0x%08lx)\n",
 345                    list->magic, SL_ENTRY_MAGIC);
 346         }
 347         printf("\nEntry %p <0x%08lx, %p> has %2d levels\n",
 348                entry, entry->key, entry->value, entry->levels);
 349         for (i = 0; i < entry->levels; i++) {
 350             if (entry->forward[i]) {
 351                 printf("   %2d: %p <0x%08lx, %p>\n",
 352                        i,
 353                        entry->forward[i],
 354                        entry->forward[i]->key,
 355                        entry->forward[i]->value);
 356             } else {
 357                 printf("   %2d: %p\n", i, entry->forward[i]);
 358             }
 359         }
 360     }
 361 }
 362
 363 #if SL_MAIN
 364 static void print(SkipListPtr list)
 365 {
 366     unsigned long key;
 367     void          *value;
 368
 369     if (N(SLFirst)(list, &key, &value)) {
 370         do {
 371             printf("key = %5lu, value = %p\n", key, value);
 372         } while (N(SLNext)(list, &key, &value));
 373     }
 374 }
 375
 376 static double do_time(int size, int iter)
 377 {
 378     SkipListPtr    list;
 379     int            i, j;
 380     unsigned long  keys[1000000];
 381     unsigned long  previous;
 382     unsigned long  key;
 383     void           *value;
 384     struct timeval start, stop;
 385     double         usec;
 386     SL_RANDOM_DECL;
 387
 388     SL_RANDOM_INIT(12345);
 389
 390     list = N(SLCreate)();
 391
 392     for (i = 0; i < size; i++) {
 393         keys[i] = SL_RANDOM;
 394         N(SLInsert)(list, keys[i], NULL);
 395     }
 396
 397     previous = 0;
 398     if (N(SLFirst)(list, &key, &value)) {
 399         do {
 400             if (key <= previous) {
 401                 printf( "%lu !< %lu\n", previous, key);
 402             }
 403             previous = key;
 404         } while (N(SLNext)(list, &key, &value));
 405     }
 406
 407     gettimeofday(&start, NULL);
 408     for (j = 0; j < iter; j++) {
 409         for (i = 0; i < size; i++) {
 410             if (N(SLLookup)(list, keys[i], &value))
 411                 printf("Error %lu %d\n", keys[i], i);
 412         }
 413     }
 414     gettimeofday(&stop, NULL);
 415
 416     usec = (double)(stop.tv_sec * 1000000 + stop.tv_usec
 417                     - start.tv_sec * 1000000 - start.tv_usec) / (size * iter);
 418
 419     printf("%0.2f microseconds for list length %d\n", usec, size);
 420
 421     N(SLDestroy)(list);
 422
 423     return usec;
 424 }
 425
 426 static void print_neighbors(void *list, unsigned long key)
 427 {
 428     unsigned long prev_key = 0;
 429     unsigned long next_key = 0;
 430     void          *prev_value;
 431     void          *next_value;
 432     int           retval;
 433
 434     retval = drmSLLookupNeighbors(list, key,
 435                                   &prev_key, &prev_value,
 436                                   &next_key, &next_value);
 437     printf("Neighbors of %5lu: %d %5lu %5lu\n",
 438            key, retval, prev_key, next_key);
 439 }
 440
 441 int main(void)
 442 {
 443     SkipListPtr    list;
 444     double         usec, usec2, usec3, usec4;
 445
 446     list = N(SLCreate)();
 447     printf( "list at %p\n", list);
 448
 449     print(list);
 450     printf("\n==============================\n\n");
 451
 452     N(SLInsert)(list, 123, NULL);
 453     N(SLInsert)(list, 213, NULL);
 454     N(SLInsert)(list, 50, NULL);
 455     print(list);
 456     printf("\n==============================\n\n");
 457
 458     print_neighbors(list, 0);
 459     print_neighbors(list, 50);
 460     print_neighbors(list, 51);
 461     print_neighbors(list, 123);
 462     print_neighbors(list, 200);
 463     print_neighbors(list, 213);
 464     print_neighbors(list, 256);
 465     printf("\n==============================\n\n");
 466
 467     N(SLDelete)(list, 50);
 468     print(list);
 469     printf("\n==============================\n\n");
 470
 471     N(SLDump)(list);
 472     N(SLDestroy)(list);
 473     printf("\n==============================\n\n");
 474
 475     usec  = do_time(100, 10000);
 476     usec2 = do_time(1000, 500);
 477     printf("Table size increased by %0.2f, search time increased by %0.2f\n",
 478            1000.0/100.0, usec2 / usec);
 479
 480     usec3 = do_time(10000, 50);
 481     printf("Table size increased by %0.2f, search time increased by %0.2f\n",
 482            10000.0/100.0, usec3 / usec);
 483
 484     usec4 = do_time(100000, 4);
 485     printf("Table size increased by %0.2f, search time increased by %0.2f\n",
 486            100000.0/100.0, usec4 / usec);
 487
 488     return 0;
 489 }
 490 #endif