xf86drmSL.c - platform/external/libdrm - Gitiles

 /* xf86drmSL.c -- Skip list support
  * Created: Mon May 10 09:28:13 1999 by faith@precisioninsight.com
  *
  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
  * All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice (including the next
  * paragraph) shall be included in all copies or substantial portions of the
  * Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  * DEALINGS IN THE SOFTWARE.
  *
  * Authors: Rickard E. (Rik) Faith <faith@valinux.com>
  *
  * DESCRIPTION
  *
  * This file contains a straightforward skip list implementation.n
  *
  * FUTURE ENHANCEMENTS
  *
  * REFERENCES
  *
  * [Pugh90] William Pugh.  Skip Lists: A Probabilistic Alternative to
  * Balanced Trees. CACM 33(6), June 1990, pp. 668-676.
  *
  */

 #include <stdio.h>
 #include <stdlib.h>

 #include "libdrm_macros.h"
 #include "xf86drm.h"

 #define SL_LIST_MAGIC  0xfacade00LU
 #define SL_ENTRY_MAGIC 0x00fab1edLU
 #define SL_FREED_MAGIC 0xdecea5edLU
 #define SL_MAX_LEVEL   16
 #define SL_RANDOM_SEED 0xc01055a1LU

 #define SL_RANDOM_DECL        static void *state = NULL
 #define SL_RANDOM_INIT(seed)  if (!state) state = drmRandomCreate(seed)
 #define SL_RANDOM             drmRandom(state)

 typedef struct SLEntry {
     unsigned long     magic;	   /* SL_ENTRY_MAGIC */
     unsigned long     key;
     void              *value;
     int               levels;
     struct SLEntry    *forward[1]; /* variable sized array */
 } SLEntry, *SLEntryPtr;

 typedef struct SkipList {
     unsigned long    magic;	/* SL_LIST_MAGIC */
     int              level;
     int              count;
     SLEntryPtr       head;
     SLEntryPtr       p0;	/* Position for iteration */
 } SkipList, *SkipListPtr;

 static SLEntryPtr SLCreateEntry(int max_level, unsigned long key, void *value)
 {
     SLEntryPtr entry;

     if (max_level < 0 || max_level > SL_MAX_LEVEL) max_level = SL_MAX_LEVEL;

     entry         = drmMalloc(sizeof(*entry)
 			     + (max_level + 1) * sizeof(entry->forward[0]));
     if (!entry) return NULL;
     entry->magic  = SL_ENTRY_MAGIC;
     entry->key    = key;
     entry->value  = value;
     entry->levels = max_level + 1;

     return entry;
 }

 static int SLRandomLevel(void)
 {
     int level = 1;
     SL_RANDOM_DECL;

     SL_RANDOM_INIT(SL_RANDOM_SEED);

     while ((SL_RANDOM & 0x01) && level < SL_MAX_LEVEL) ++level;
     return level;
 }

 drm_public void *drmSLCreate(void)
 {
     SkipListPtr  list;
     int          i;

     list           = drmMalloc(sizeof(*list));
     if (!list) return NULL;
     list->magic    = SL_LIST_MAGIC;
     list->level    = 0;
     list->head     = SLCreateEntry(SL_MAX_LEVEL, 0, NULL);
     list->count    = 0;

     for (i = 0; i <= SL_MAX_LEVEL; i++) list->head->forward[i] = NULL;

     return list;
 }

 drm_public int drmSLDestroy(void *l)
 {
     SkipListPtr   list  = (SkipListPtr)l;
     SLEntryPtr    entry;
     SLEntryPtr    next;

     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */

     for (entry = list->head; entry; entry = next) {
 	if (entry->magic != SL_ENTRY_MAGIC) return -1; /* Bad magic */
 	next         = entry->forward[0];
 	entry->magic = SL_FREED_MAGIC;
 	drmFree(entry);
     }

     list->magic = SL_FREED_MAGIC;
     drmFree(list);
     return 0;
 }

 static SLEntryPtr SLLocate(void *l, unsigned long key, SLEntryPtr *update)
 {
     SkipListPtr   list  = (SkipListPtr)l;
     SLEntryPtr    entry;
     int           i;

     if (list->magic != SL_LIST_MAGIC) return NULL;

     for (i = list->level, entry = list->head; i >= 0; i--) {
 	while (entry->forward[i] && entry->forward[i]->key < key)
 	    entry = entry->forward[i];
 	update[i] = entry;
     }

     return entry->forward[0];
 }

 drm_public int drmSLInsert(void *l, unsigned long key, void *value)
 {
     SkipListPtr   list  = (SkipListPtr)l;
     SLEntryPtr    entry;
     SLEntryPtr    update[SL_MAX_LEVEL + 1];
     int           level;
     int           i;

     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */

     entry = SLLocate(list, key, update);

     if (entry && entry->key == key) return 1; /* Already in list */


     level = SLRandomLevel();
     if (level > list->level) {
 	level = ++list->level;
 	update[level] = list->head;
     }

     entry = SLCreateEntry(level, key, value);

 				/* Fix up forward pointers */
     for (i = 0; i <= level; i++) {
 	entry->forward[i]     = update[i]->forward[i];
 	update[i]->forward[i] = entry;
     }

     ++list->count;
     return 0;			/* Added to table */
 }

 drm_public int drmSLDelete(void *l, unsigned long key)
 {
     SkipListPtr   list = (SkipListPtr)l;
     SLEntryPtr    update[SL_MAX_LEVEL + 1];
     SLEntryPtr    entry;
     int           i;

     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */

     entry = SLLocate(list, key, update);

     if (!entry || entry->key != key) return 1; /* Not found */

 				/* Fix up forward pointers */
     for (i = 0; i <= list->level; i++) {
 	if (update[i]->forward[i] == entry)
 	    update[i]->forward[i] = entry->forward[i];
     }

     entry->magic = SL_FREED_MAGIC;
     drmFree(entry);

     while (list->level && !list->head->forward[list->level]) --list->level;
     --list->count;
     return 0;
 }

 drm_public int drmSLLookup(void *l, unsigned long key, void **value)
 {
     SkipListPtr   list = (SkipListPtr)l;
     SLEntryPtr    update[SL_MAX_LEVEL + 1];
     SLEntryPtr    entry;

     entry = SLLocate(list, key, update);

     if (entry && entry->key == key) {
 	*value = entry;
 	return 0;
     }
     *value = NULL;
     return -1;
 }

 drm_public int drmSLLookupNeighbors(void *l, unsigned long key,
                                     unsigned long *prev_key, void **prev_value,
                                     unsigned long *next_key, void **next_value)
 {
     SkipListPtr   list = (SkipListPtr)l;
     SLEntryPtr    update[SL_MAX_LEVEL + 1] = {0};
     int           retcode = 0;

     SLLocate(list, key, update);

     *prev_key   = *next_key   = key;
     *prev_value = *next_value = NULL;

     if (update[0]) {
 	*prev_key   = update[0]->key;
 	*prev_value = update[0]->value;
 	++retcode;
 	if (update[0]->forward[0]) {
 	    *next_key   = update[0]->forward[0]->key;
 	    *next_value = update[0]->forward[0]->value;
 	    ++retcode;
 	}
     }
     return retcode;
 }

 drm_public int drmSLNext(void *l, unsigned long *key, void **value)
 {
     SkipListPtr   list = (SkipListPtr)l;
     SLEntryPtr    entry;

     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */

     entry    = list->p0;

     if (entry) {
 	list->p0 = entry->forward[0];
 	*key     = entry->key;
 	*value   = entry->value;
 	return 1;
     }
     list->p0 = NULL;
     return 0;
 }

 drm_public int drmSLFirst(void *l, unsigned long *key, void **value)
 {
     SkipListPtr   list = (SkipListPtr)l;

     if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */

     list->p0 = list->head->forward[0];
     return drmSLNext(list, key, value);
 }

 /* Dump internal data structures for debugging. */
 drm_public void drmSLDump(void *l)
 {
     SkipListPtr   list = (SkipListPtr)l;
     SLEntryPtr    entry;
     int           i;

     if (list->magic != SL_LIST_MAGIC) {
 	printf("Bad magic: 0x%08lx (expected 0x%08lx)\n",
 	       list->magic, SL_LIST_MAGIC);
 	return;
     }

     printf("Level = %d, count = %d\n", list->level, list->count);
     for (entry = list->head; entry; entry = entry->forward[0]) {
 	if (entry->magic != SL_ENTRY_MAGIC) {
 	    printf("Bad magic: 0x%08lx (expected 0x%08lx)\n",
 		   list->magic, SL_ENTRY_MAGIC);
 	}
 	printf("\nEntry %p <0x%08lx, %p> has %2d levels\n",
 	       entry, entry->key, entry->value, entry->levels);
 	for (i = 0; i < entry->levels; i++) {
 	    if (entry->forward[i]) {
 		printf("   %2d: %p <0x%08lx, %p>\n",
 		       i,
 		       entry->forward[i],
 		       entry->forward[i]->key,
 		       entry->forward[i]->value);
 	    } else {
 		printf("   %2d: %p\n", i, entry->forward[i]);
 	    }
 	}
     }
 }
	/* xf86drmSL.c -- Skip list support
	* Created: Mon May 10 09:28:13 1999 by faith@precisioninsight.com
	*
	* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
	* All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice (including the next
	* paragraph) shall be included in all copies or substantial portions of the
	* Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
	* DEALINGS IN THE SOFTWARE.
	*
	* Authors: Rickard E. (Rik) Faith <faith@valinux.com>
	*
	* DESCRIPTION
	*
	* This file contains a straightforward skip list implementation.n
	*
	* FUTURE ENHANCEMENTS
	*
	* REFERENCES
	*
	* [Pugh90] William Pugh. Skip Lists: A Probabilistic Alternative to
	* Balanced Trees. CACM 33(6), June 1990, pp. 668-676.
	*
	*/

	#include <stdio.h>
	#include <stdlib.h>

	#include "libdrm_macros.h"
	#include "xf86drm.h"

	#define SL_LIST_MAGIC 0xfacade00LU
	#define SL_ENTRY_MAGIC 0x00fab1edLU
	#define SL_FREED_MAGIC 0xdecea5edLU
	#define SL_MAX_LEVEL 16
	#define SL_RANDOM_SEED 0xc01055a1LU

	#define SL_RANDOM_DECL static void *state = NULL
	#define SL_RANDOM_INIT(seed) if (!state) state = drmRandomCreate(seed)
	#define SL_RANDOM drmRandom(state)

	typedef struct SLEntry {
	unsigned long magic; /* SL_ENTRY_MAGIC */
	unsigned long key;
	void *value;
	int levels;
	struct SLEntry forward[1]; / variable sized array */
	} SLEntry, *SLEntryPtr;

	typedef struct SkipList {
	unsigned long magic; /* SL_LIST_MAGIC */
	int level;
	int count;
	SLEntryPtr head;
	SLEntryPtr p0; /* Position for iteration */
	} SkipList, *SkipListPtr;

	static SLEntryPtr SLCreateEntry(int max_level, unsigned long key, void *value)
	{
	SLEntryPtr entry;

	if (max_level < 0 \|\| max_level > SL_MAX_LEVEL) max_level = SL_MAX_LEVEL;

	entry = drmMalloc(sizeof(*entry)
	+ (max_level + 1) * sizeof(entry->forward[0]));
	if (!entry) return NULL;
	entry->magic = SL_ENTRY_MAGIC;
	entry->key = key;
	entry->value = value;
	entry->levels = max_level + 1;

	return entry;
	}

	static int SLRandomLevel(void)
	{
	int level = 1;
	SL_RANDOM_DECL;

	SL_RANDOM_INIT(SL_RANDOM_SEED);

	while ((SL_RANDOM & 0x01) && level < SL_MAX_LEVEL) ++level;
	return level;
	}

	drm_public void *drmSLCreate(void)
	{
	SkipListPtr list;
	int i;

	list = drmMalloc(sizeof(*list));
	if (!list) return NULL;
	list->magic = SL_LIST_MAGIC;
	list->level = 0;
	list->head = SLCreateEntry(SL_MAX_LEVEL, 0, NULL);
	list->count = 0;

	for (i = 0; i <= SL_MAX_LEVEL; i++) list->head->forward[i] = NULL;

	return list;
	}

	drm_public int drmSLDestroy(void *l)
	{
	SkipListPtr list = (SkipListPtr)l;
	SLEntryPtr entry;
	SLEntryPtr next;

	if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */

	for (entry = list->head; entry; entry = next) {
	if (entry->magic != SL_ENTRY_MAGIC) return -1; /* Bad magic */
	next = entry->forward[0];
	entry->magic = SL_FREED_MAGIC;
	drmFree(entry);
	}

	list->magic = SL_FREED_MAGIC;
	drmFree(list);
	return 0;
	}

	static SLEntryPtr SLLocate(void l, unsigned long key, SLEntryPtr update)
	{
	SkipListPtr list = (SkipListPtr)l;
	SLEntryPtr entry;
	int i;

	if (list->magic != SL_LIST_MAGIC) return NULL;

	for (i = list->level, entry = list->head; i >= 0; i--) {
	while (entry->forward[i] && entry->forward[i]->key < key)
	entry = entry->forward[i];
	update[i] = entry;
	}

	return entry->forward[0];
	}

	drm_public int drmSLInsert(void l, unsigned long key, void value)
	{
	SkipListPtr list = (SkipListPtr)l;
	SLEntryPtr entry;
	SLEntryPtr update[SL_MAX_LEVEL + 1];
	int level;
	int i;

	if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */

	entry = SLLocate(list, key, update);

	if (entry && entry->key == key) return 1; /* Already in list */


	level = SLRandomLevel();
	if (level > list->level) {
	level = ++list->level;
	update[level] = list->head;
	}

	entry = SLCreateEntry(level, key, value);

	/* Fix up forward pointers */
	for (i = 0; i <= level; i++) {
	entry->forward[i] = update[i]->forward[i];
	update[i]->forward[i] = entry;
	}

	++list->count;
	return 0; /* Added to table */
	}

	drm_public int drmSLDelete(void *l, unsigned long key)
	{
	SkipListPtr list = (SkipListPtr)l;
	SLEntryPtr update[SL_MAX_LEVEL + 1];
	SLEntryPtr entry;
	int i;

	if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */

	entry = SLLocate(list, key, update);

	if (!entry \|\| entry->key != key) return 1; /* Not found */

	/* Fix up forward pointers */
	for (i = 0; i <= list->level; i++) {
	if (update[i]->forward[i] == entry)
	update[i]->forward[i] = entry->forward[i];
	}

	entry->magic = SL_FREED_MAGIC;
	drmFree(entry);

	while (list->level && !list->head->forward[list->level]) --list->level;
	--list->count;
	return 0;
	}

	drm_public int drmSLLookup(void l, unsigned long key, void *value)
	{
	SkipListPtr list = (SkipListPtr)l;
	SLEntryPtr update[SL_MAX_LEVEL + 1];
	SLEntryPtr entry;

	entry = SLLocate(list, key, update);

	if (entry && entry->key == key) {
	*value = entry;
	return 0;
	}
	*value = NULL;
	return -1;
	}

	drm_public int drmSLLookupNeighbors(void *l, unsigned long key,
	unsigned long prev_key, void *prev_value,
	unsigned long next_key, void *next_value)
	{
	SkipListPtr list = (SkipListPtr)l;
	SLEntryPtr update[SL_MAX_LEVEL + 1] = {0};
	int retcode = 0;

	SLLocate(list, key, update);

	prev_key = next_key = key;
	prev_value = next_value = NULL;

	if (update[0]) {
	*prev_key = update[0]->key;
	*prev_value = update[0]->value;
	++retcode;
	if (update[0]->forward[0]) {
	*next_key = update[0]->forward[0]->key;
	*next_value = update[0]->forward[0]->value;
	++retcode;
	}
	}
	return retcode;
	}

	drm_public int drmSLNext(void l, unsigned long key, void **value)
	{
	SkipListPtr list = (SkipListPtr)l;
	SLEntryPtr entry;

	if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */

	entry = list->p0;

	if (entry) {
	list->p0 = entry->forward[0];
	*key = entry->key;
	*value = entry->value;
	return 1;
	}
	list->p0 = NULL;
	return 0;
	}

	drm_public int drmSLFirst(void l, unsigned long key, void **value)
	{
	SkipListPtr list = (SkipListPtr)l;

	if (list->magic != SL_LIST_MAGIC) return -1; /* Bad magic */

	list->p0 = list->head->forward[0];
	return drmSLNext(list, key, value);
	}

	/* Dump internal data structures for debugging. */
	drm_public void drmSLDump(void *l)
	{
	SkipListPtr list = (SkipListPtr)l;
	SLEntryPtr entry;
	int i;

	if (list->magic != SL_LIST_MAGIC) {
	printf("Bad magic: 0x%08lx (expected 0x%08lx)\n",
	list->magic, SL_LIST_MAGIC);
	return;
	}

	printf("Level = %d, count = %d\n", list->level, list->count);
	for (entry = list->head; entry; entry = entry->forward[0]) {
	if (entry->magic != SL_ENTRY_MAGIC) {
	printf("Bad magic: 0x%08lx (expected 0x%08lx)\n",
	list->magic, SL_ENTRY_MAGIC);
	}
	printf("\nEntry %p <0x%08lx, %p> has %2d levels\n",
	entry, entry->key, entry->value, entry->levels);
	for (i = 0; i < entry->levels; i++) {
	if (entry->forward[i]) {
	printf(" %2d: %p <0x%08lx, %p>\n",
	i,
	entry->forward[i],
	entry->forward[i]->key,
	entry->forward[i]->value);
	} else {
	printf(" %2d: %p\n", i, entry->forward[i]);
	}
	}
	}
	}