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 SL_LIST_MAGIC  0xfacade00LU
  61 #define SL_ENTRY_MAGIC 0x00fab1edLU
  62 #define SL_FREED_MAGIC 0xdecea5edLU
  63 #define SL_MAX_LEVEL   16
  64 #define SL_DEBUG       0
  65 #define SL_RANDOM_SEED 0xc01055a1LU
  66
  67 #if SL_MAIN
  68 #define SL_ALLOC malloc
  69 #define SL_FREE  free
  70 #define SL_RANDOM_DECL        static int state = 0;
  71 #define SL_RANDOM_INIT(seed)  if (!state) { srandom(seed); ++state; }
  72 #define SL_RANDOM             random()
  73 #else
  74 #define SL_ALLOC drmMalloc
  75 #define SL_FREE  drmFree
  76 #define SL_RANDOM_DECL        static void *state = NULL
  77 #define SL_RANDOM_INIT(seed)  if (!state) state = drmRandomCreate(seed)
  78 #define SL_RANDOM             drmRandom(state)
  79
  80 #endif
  81
  82 typedef struct SLEntry {
  83     unsigned long     magic;       /* SL_ENTRY_MAGIC */
  84     unsigned long     key;
  85     void              *value;
  86     int               levels;
  87     struct SLEntry    *forward[1]; /* variable sized array */
  88 } SLEntry, *SLEntryPtr;
  89
  90 typedef struct SkipList {
  91     unsigned long    magic;     /* SL_LIST_MAGIC */
  92     int              level;
  93     int              count;
  94     SLEntryPtr       head;
  95     SLEntryPtr       p0;        /* Position for iteration */
  96 } SkipList, *SkipListPtr;
  97
  98 #if SL_MAIN
  99 extern void *drmSLCreate(void);
 100 extern int  drmSLDestroy(void *l);
 101 extern int  drmSLLookup(void *l, unsigned long key, void **value);
 102 extern int  drmSLInsert(void *l, unsigned long key, void *value);
 103 extern int  drmSLDelete(void *l, unsigned long key);
 104 extern int  drmSLNext(void *l, unsigned long *key, void **value);
 105 extern int  drmSLFirst(void *l, unsigned long *key, void **value);
 106 extern void drmSLDump(void *l);
 107 extern int  drmSLLookupNeighbors(void *l, unsigned long key,
 108                                  unsigned long *prev_key, void **prev_value,
 109                                  unsigned long *next_key, void **next_value);
 110 #endif
 111
 112 static SLEntryPtr SLCreateEntry(int max_level, unsigned long key, void *value)
 113 {
 114     SLEntryPtr entry;
 115
 116     if (max_level < 0 || max_level > SL_MAX_LEVEL) max_level = SL_MAX_LEVEL;
 117
 118     entry         = SL_ALLOC(sizeof(*entry)
 119                              + (max_level + 1) * sizeof(entry->forward[0]));
 120     if (!entry) return NULL;
 121     entry->magic  = SL_ENTRY_MAGIC;
 122     entry->key    = key;
 123     entry->value  = value;
 124     entry->levels = max_level + 1;
 125
 126     return entry;
 127 }
 128
 129 static int SLRandomLevel(void)
 130 {
 131     int level = 1;
 132     SL_RANDOM_DECL;
 133
 134     SL_RANDOM_INIT(SL_RANDOM_SEED);
 135
 136     while ((SL_RANDOM & 0x01) && level < SL_MAX_LEVEL) ++level;
 137     return level;
 138 }
 139
 140 void *drmSLCreate(void)
 141 {
 142     SkipListPtr  list;
 143     int          i;
 144
 145     list           = SL_ALLOC(sizeof(*list));
 146     if (!list) return NULL;
 147     list->magic    = SL_LIST_MAGIC;
 148     list->level    = 0;
 149     list->head     = SLCreateEntry(SL_MAX_LEVEL, 0, NULL);
 150     list->count    = 0;
 151
 152     for (i = 0; i <= SL_MAX_LEVEL; i++) list->head->forward[i] = NULL;
 153
 154     return list;
 155 }
 156
 157 int drmSLDestroy(void *l)
 158 {
 159     SkipListPtr   list  = (SkipListPtr)l;
 160     SLEntryPtr    entry;
 161     SLEntryPtr    next;
 162
 163     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */
 164
 165     for (entry = list->head; entry; entry = next) {
 166         if (entry->magic != SL_ENTRY_MAGIC) return -1; /* Bad magic */
 167         next         = entry->forward[0];
 168         entry->magic = SL_FREED_MAGIC;
 169         SL_FREE(entry);
 170     }
 171
 172     list->magic = SL_FREED_MAGIC;
 173     SL_FREE(list);
 174     return 0;
 175 }
 176
 177 static SLEntryPtr SLLocate(void *l, unsigned long key, SLEntryPtr *update)
 178 {
 179     SkipListPtr   list  = (SkipListPtr)l;
 180     SLEntryPtr    entry;
 181     int           i;
 182
 183     if (list->magic != SL_LIST_MAGIC) return NULL;
 184
 185     for (i = list->level, entry = list->head; i >= 0; i--) {
 186         while (entry->forward[i] && entry->forward[i]->key < key)
 187             entry = entry->forward[i];
 188         update[i] = entry;
 189     }
 190
 191     return entry->forward[0];
 192 }
 193
 194 int drmSLInsert(void *l, unsigned long key, void *value)
 195 {
 196     SkipListPtr   list  = (SkipListPtr)l;
 197     SLEntryPtr    entry;
 198     SLEntryPtr    update[SL_MAX_LEVEL + 1];
 199     int           level;
 200     int           i;
 201
 202     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */
 203
 204     entry = SLLocate(list, key, update);
 205
 206     if (entry && entry->key == key) return 1; /* Already in list */
 207
 208
 209     level = SLRandomLevel();
 210     if (level > list->level) {
 211         level = ++list->level;
 212         update[level] = list->head;
 213     }
 214
 215     entry = SLCreateEntry(level, key, value);
 216
 217                                 /* Fix up forward pointers */
 218     for (i = 0; i <= level; i++) {
 219         entry->forward[i]     = update[i]->forward[i];
 220         update[i]->forward[i] = entry;
 221     }
 222
 223     ++list->count;
 224     return 0;                   /* Added to table */
 225 }
 226
 227 int drmSLDelete(void *l, unsigned long key)
 228 {
 229     SkipListPtr   list = (SkipListPtr)l;
 230     SLEntryPtr    update[SL_MAX_LEVEL + 1];
 231     SLEntryPtr    entry;
 232     int           i;
 233
 234     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */
 235
 236     entry = SLLocate(list, key, update);
 237
 238     if (!entry || entry->key != key) return 1; /* Not found */
 239
 240                                 /* Fix up forward pointers */
 241     for (i = 0; i <= list->level; i++) {
 242         if (update[i]->forward[i] == entry)
 243             update[i]->forward[i] = entry->forward[i];
 244     }
 245
 246     entry->magic = SL_FREED_MAGIC;
 247     SL_FREE(entry);
 248
 249     while (list->level && !list->head->forward[list->level]) --list->level;
 250     --list->count;
 251     return 0;
 252 }
 253
 254 int drmSLLookup(void *l, unsigned long key, void **value)
 255 {
 256     SkipListPtr   list = (SkipListPtr)l;
 257     SLEntryPtr    update[SL_MAX_LEVEL + 1];
 258     SLEntryPtr    entry;
 259
 260     entry = SLLocate(list, key, update);
 261
 262     if (entry && entry->key == key) {
 263         *value = entry;
 264         return 0;
 265     }
 266     *value = NULL;
 267     return -1;
 268 }
 269
 270 int drmSLLookupNeighbors(void *l, unsigned long key,
 271                          unsigned long *prev_key, void **prev_value,
 272                          unsigned long *next_key, void **next_value)
 273 {
 274     SkipListPtr   list = (SkipListPtr)l;
 275     SLEntryPtr    update[SL_MAX_LEVEL + 1];
 276     SLEntryPtr    entry;
 277     int           retcode = 0;
 278
 279     entry = SLLocate(list, key, update);
 280
 281     *prev_key   = *next_key   = key;
 282     *prev_value = *next_value = NULL;
 283
 284     if (update[0]) {
 285         *prev_key   = update[0]->key;
 286         *prev_value = update[0]->value;
 287         ++retcode;
 288         if (update[0]->forward[0]) {
 289             *next_key   = update[0]->forward[0]->key;
 290             *next_value = update[0]->forward[0]->value;
 291             ++retcode;
 292         }
 293     }
 294     return retcode;
 295 }
 296
 297 int drmSLNext(void *l, unsigned long *key, void **value)
 298 {
 299     SkipListPtr   list = (SkipListPtr)l;
 300     SLEntryPtr    entry;
 301
 302     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */
 303
 304     entry    = list->p0;
 305
 306     if (entry) {
 307         list->p0 = entry->forward[0];
 308         *key     = entry->key;
 309         *value   = entry->value;
 310         return 1;
 311     }
 312     list->p0 = NULL;
 313     return 0;
 314 }
 315
 316 int drmSLFirst(void *l, unsigned long *key, void **value)
 317 {
 318     SkipListPtr   list = (SkipListPtr)l;
 319
 320     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */
 321
 322     list->p0 = list->head->forward[0];
 323     return drmSLNext(list, key, value);
 324 }
 325
 326 /* Dump internal data structures for debugging. */
 327 void drmSLDump(void *l)
 328 {
 329     SkipListPtr   list = (SkipListPtr)l;
 330     SLEntryPtr    entry;
 331     int           i;
 332
 333     if (list->magic != SL_LIST_MAGIC) {
 334         printf("Bad magic: 0x%08lx (expected 0x%08lx)\n",
 335                list->magic, SL_LIST_MAGIC);
 336         return;
 337     }
 338
 339     printf("Level = %d, count = %d\n", list->level, list->count);
 340     for (entry = list->head; entry; entry = entry->forward[0]) {
 341         if (entry->magic != SL_ENTRY_MAGIC) {
 342             printf("Bad magic: 0x%08lx (expected 0x%08lx)\n",
 343                    list->magic, SL_ENTRY_MAGIC);
 344         }
 345         printf("\nEntry %p <0x%08lx, %p> has %2d levels\n",
 346                entry, entry->key, entry->value, entry->levels);
 347         for (i = 0; i < entry->levels; i++) {
 348             if (entry->forward[i]) {
 349                 printf("   %2d: %p <0x%08lx, %p>\n",
 350                        i,
 351                        entry->forward[i],
 352                        entry->forward[i]->key,
 353                        entry->forward[i]->value);
 354             } else {
 355                 printf("   %2d: %p\n", i, entry->forward[i]);
 356             }
 357         }
 358     }
 359 }
 360
 361 #if SL_MAIN
 362 static void print(SkipListPtr list)
 363 {
 364     unsigned long key;
 365     void          *value;
 366
 367     if (drmSLFirst(list, &key, &value)) {
 368         do {
 369             printf("key = %5lu, value = %p\n", key, value);
 370         } while (drmSLNext(list, &key, &value));
 371     }
 372 }
 373
 374 static double do_time(int size, int iter)
 375 {
 376     SkipListPtr    list;
 377     int            i, j;
 378     unsigned long  keys[1000000];
 379     unsigned long  previous;
 380     unsigned long  key;
 381     void           *value;
 382     struct timeval start, stop;
 383     double         usec;
 384     SL_RANDOM_DECL;
 385
 386     SL_RANDOM_INIT(12345);
 387
 388     list = drmSLCreate();
 389
 390     for (i = 0; i < size; i++) {
 391         keys[i] = SL_RANDOM;
 392         drmSLInsert(list, keys[i], NULL);
 393     }
 394
 395     previous = 0;
 396     if (drmSLFirst(list, &key, &value)) {
 397         do {
 398             if (key <= previous) {
 399                 printf( "%lu !< %lu\n", previous, key);
 400             }
 401             previous = key;
 402         } while (drmSLNext(list, &key, &value));
 403     }
 404
 405     gettimeofday(&start, NULL);
 406     for (j = 0; j < iter; j++) {
 407         for (i = 0; i < size; i++) {
 408             if (drmSLLookup(list, keys[i], &value))
 409                 printf("Error %lu %d\n", keys[i], i);
 410         }
 411     }
 412     gettimeofday(&stop, NULL);
 413
 414     usec = (double)(stop.tv_sec * 1000000 + stop.tv_usec
 415                     - start.tv_sec * 1000000 - start.tv_usec) / (size * iter);
 416
 417     printf("%0.2f microseconds for list length %d\n", usec, size);
 418
 419     drmSLDestroy(list);
 420
 421     return usec;
 422 }
 423
 424 static void print_neighbors(void *list, unsigned long key)
 425 {
 426     unsigned long prev_key = 0;
 427     unsigned long next_key = 0;
 428     void          *prev_value;
 429     void          *next_value;
 430     int           retval;
 431
 432     retval = drmSLLookupNeighbors(list, key,
 433                                   &prev_key, &prev_value,
 434                                   &next_key, &next_value);
 435     printf("Neighbors of %5lu: %d %5lu %5lu\n",
 436            key, retval, prev_key, next_key);
 437 }
 438
 439 int main(void)
 440 {
 441     SkipListPtr    list;
 442     double         usec, usec2, usec3, usec4;
 443
 444     list = drmSLCreate();
 445     printf( "list at %p\n", list);
 446
 447     print(list);
 448     printf("\n==============================\n\n");
 449
 450     drmSLInsert(list, 123, NULL);
 451     drmSLInsert(list, 213, NULL);
 452     drmSLInsert(list, 50, NULL);
 453     print(list);
 454     printf("\n==============================\n\n");
 455
 456     print_neighbors(list, 0);
 457     print_neighbors(list, 50);
 458     print_neighbors(list, 51);
 459     print_neighbors(list, 123);
 460     print_neighbors(list, 200);
 461     print_neighbors(list, 213);
 462     print_neighbors(list, 256);
 463     printf("\n==============================\n\n");
 464
 465     drmSLDelete(list, 50);
 466     print(list);
 467     printf("\n==============================\n\n");
 468
 469     drmSLDump(list);
 470     drmSLDestroy(list);
 471     printf("\n==============================\n\n");
 472
 473     usec  = do_time(100, 10000);
 474     usec2 = do_time(1000, 500);
 475     printf("Table size increased by %0.2f, search time increased by %0.2f\n",
 476            1000.0/100.0, usec2 / usec);
 477
 478     usec3 = do_time(10000, 50);
 479     printf("Table size increased by %0.2f, search time increased by %0.2f\n",
 480            10000.0/100.0, usec3 / usec);
 481
 482     usec4 = do_time(100000, 4);
 483     printf("Table size increased by %0.2f, search time increased by %0.2f\n",
 484            100000.0/100.0, usec4 / usec);
 485
 486     return 0;
 487 }
 488 #endif