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diff --git a/src/glx/x11/glxhash.c b/src/glx/x11/glxhash.c
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-/* glxhash.c -- Small hash table support for integer -> integer mapping
- * Taken from libdrm.
- *
- * Created: Sun Apr 18 09:35:45 1999 by [email protected]
- *
- * 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 <[email protected]>
- *
- * DESCRIPTION
- *
- * This file contains a straightforward implementation of a fixed-sized
- * hash table using self-organizing linked lists [Knuth73, pp. 398-399] for
- * collision resolution. There are two potentially interesting things
- * about this implementation:
- *
- * 1) The table is power-of-two sized. Prime sized tables are more
- * traditional, but do not have a significant advantage over power-of-two
- * sized table, especially when double hashing is not used for collision
- * resolution.
- *
- * 2) The hash computation uses a table of random integers [Hanson97,
- * pp. 39-41].
- *
- * FUTURE ENHANCEMENTS
- *
- * With a table size of 512, the current implementation is sufficient for a
- * few hundred keys. Since this is well above the expected size of the
- * tables for which this implementation was designed, the implementation of
- * dynamic hash tables was postponed until the need arises. A common (and
- * naive) approach to dynamic hash table implementation simply creates a
- * new hash table when necessary, rehashes all the data into the new table,
- * and destroys the old table. The approach in [Larson88] is superior in
- * two ways: 1) only a portion of the table is expanded when needed,
- * distributing the expansion cost over several insertions, and 2) portions
- * of the table can be locked, enabling a scalable thread-safe
- * implementation.
- *
- * REFERENCES
- *
- * [Hanson97] David R. Hanson. C Interfaces and Implementations:
- * Techniques for Creating Reusable Software. Reading, Massachusetts:
- * Addison-Wesley, 1997.
- *
- * [Knuth73] Donald E. Knuth. The Art of Computer Programming. Volume 3:
- * Sorting and Searching. Reading, Massachusetts: Addison-Wesley, 1973.
- *
- * [Larson88] Per-Ake Larson. "Dynamic Hash Tables". CACM 31(4), April
- * 1988, pp. 446-457.
- *
- */
-
-#include "glxhash.h"
-#include <X11/Xfuncproto.h>
-
-#define HASH_MAIN 0
-
-#include <stdio.h>
-#include <stdlib.h>
-
-#define HASH_MAGIC 0xdeadbeef
-#define HASH_DEBUG 0
-#define HASH_SIZE 512 /* Good for about 100 entries */
- /* If you change this value, you probably
- have to change the HashHash hashing
- function! */
-
-#define HASH_ALLOC malloc
-#define HASH_FREE free
-#define HASH_RANDOM_DECL
-#define HASH_RANDOM_INIT(seed) srandom(seed)
-#define HASH_RANDOM random()
-#define HASH_RANDOM_DESTROY
-
-typedef struct __glxHashBucket {
- unsigned long key;
- void *value;
- struct __glxHashBucket *next;
-} __glxHashBucket, *__glxHashBucketPtr;
-
-typedef struct __glxHashTable *__glxHashTablePtr;
-struct __glxHashTable {
- unsigned long magic;
- unsigned long entries;
- unsigned long hits; /* At top of linked list */
- unsigned long partials; /* Not at top of linked list */
- unsigned long misses; /* Not in table */
- __glxHashBucketPtr buckets[HASH_SIZE];
- int p0;
- __glxHashBucketPtr p1;
-};
-
-static unsigned long HashHash(unsigned long key)
-{
- unsigned long hash = 0;
- unsigned long tmp = key;
- static int init = 0;
- static unsigned long scatter[256];
- int i;
-
- if (!init) {
- HASH_RANDOM_DECL;
- HASH_RANDOM_INIT(37);
- for (i = 0; i < 256; i++) scatter[i] = HASH_RANDOM;
- HASH_RANDOM_DESTROY;
- ++init;
- }
-
- while (tmp) {
- hash = (hash << 1) + scatter[tmp & 0xff];
- tmp >>= 8;
- }
-
- hash %= HASH_SIZE;
-#if HASH_DEBUG
- printf( "Hash(%d) = %d\n", key, hash);
-#endif
- return hash;
-}
-
-_X_HIDDEN __glxHashTable *__glxHashCreate(void)
-{
- __glxHashTablePtr table;
- int i;
-
- table = HASH_ALLOC(sizeof(*table));
- if (!table) return NULL;
- table->magic = HASH_MAGIC;
- table->entries = 0;
- table->hits = 0;
- table->partials = 0;
- table->misses = 0;
-
- for (i = 0; i < HASH_SIZE; i++) table->buckets[i] = NULL;
- return table;
-}
-
-_X_HIDDEN int __glxHashDestroy(__glxHashTable *t)
-{
- __glxHashTablePtr table = (__glxHashTablePtr)t;
- __glxHashBucketPtr bucket;
- __glxHashBucketPtr next;
- int i;
-
- if (table->magic != HASH_MAGIC) return -1; /* Bad magic */
-
- for (i = 0; i < HASH_SIZE; i++) {
- for (bucket = table->buckets[i]; bucket;) {
- next = bucket->next;
- HASH_FREE(bucket);
- bucket = next;
- }
- }
- HASH_FREE(table);
- return 0;
-}
-
-/* Find the bucket and organize the list so that this bucket is at the
- top. */
-
-static __glxHashBucketPtr HashFind(__glxHashTablePtr table,
- unsigned long key, unsigned long *h)
-{
- unsigned long hash = HashHash(key);
- __glxHashBucketPtr prev = NULL;
- __glxHashBucketPtr bucket;
-
- if (h) *h = hash;
-
- for (bucket = table->buckets[hash]; bucket; bucket = bucket->next) {
- if (bucket->key == key) {
- if (prev) {
- /* Organize */
- prev->next = bucket->next;
- bucket->next = table->buckets[hash];
- table->buckets[hash] = bucket;
- ++table->partials;
- } else {
- ++table->hits;
- }
- return bucket;
- }
- prev = bucket;
- }
- ++table->misses;
- return NULL;
-}
-
-_X_HIDDEN int __glxHashLookup(__glxHashTable *t,
- unsigned long key, void **value)
-{
- __glxHashTablePtr table = (__glxHashTablePtr)t;
- __glxHashBucketPtr bucket;
-
- if (!table || table->magic != HASH_MAGIC) return -1; /* Bad magic */
-
- bucket = HashFind(table, key, NULL);
- if (!bucket) return 1; /* Not found */
- *value = bucket->value;
- return 0; /* Found */
-}
-
-_X_HIDDEN int __glxHashInsert(__glxHashTable *t,
- unsigned long key, void *value)
-{
- __glxHashTablePtr table = (__glxHashTablePtr)t;
- __glxHashBucketPtr bucket;
- unsigned long hash;
-
- if (table->magic != HASH_MAGIC) return -1; /* Bad magic */
-
- if (HashFind(table, key, &hash)) return 1; /* Already in table */
-
- bucket = HASH_ALLOC(sizeof(*bucket));
- if (!bucket) return -1; /* Error */
- bucket->key = key;
- bucket->value = value;
- bucket->next = table->buckets[hash];
- table->buckets[hash] = bucket;
-#if HASH_DEBUG
- printf("Inserted %d at %d/%p\n", key, hash, bucket);
-#endif
- return 0; /* Added to table */
-}
-
-_X_HIDDEN int __glxHashDelete(__glxHashTable *t, unsigned long key)
-{
- __glxHashTablePtr table = (__glxHashTablePtr)t;
- unsigned long hash;
- __glxHashBucketPtr bucket;
-
- if (table->magic != HASH_MAGIC) return -1; /* Bad magic */
-
- bucket = HashFind(table, key, &hash);
-
- if (!bucket) return 1; /* Not found */
-
- table->buckets[hash] = bucket->next;
- HASH_FREE(bucket);
- return 0;
-}
-
-_X_HIDDEN int __glxHashNext(__glxHashTable *t,
- unsigned long *key, void **value)
-{
- __glxHashTablePtr table = (__glxHashTablePtr)t;
-
- while (table->p0 < HASH_SIZE) {
- if (table->p1) {
- *key = table->p1->key;
- *value = table->p1->value;
- table->p1 = table->p1->next;
- return 1;
- }
- table->p1 = table->buckets[table->p0];
- ++table->p0;
- }
- return 0;
-}
-
-_X_HIDDEN int __glxHashFirst(__glxHashTable *t,
- unsigned long *key, void **value)
-{
- __glxHashTablePtr table = (__glxHashTablePtr)t;
-
- if (table->magic != HASH_MAGIC) return -1; /* Bad magic */
-
- table->p0 = 0;
- table->p1 = table->buckets[0];
- return __glxHashNext(table, key, value);
-}
-
-#if HASH_MAIN
-#define DIST_LIMIT 10
-static int dist[DIST_LIMIT];
-
-static void clear_dist(void) {
- int i;
-
- for (i = 0; i < DIST_LIMIT; i++) dist[i] = 0;
-}
-
-static int count_entries(__glxHashBucketPtr bucket)
-{
- int count = 0;
-
- for (; bucket; bucket = bucket->next) ++count;
- return count;
-}
-
-static void update_dist(int count)
-{
- if (count >= DIST_LIMIT) ++dist[DIST_LIMIT-1];
- else ++dist[count];
-}
-
-static void compute_dist(__glxHashTablePtr table)
-{
- int i;
- __glxHashBucketPtr bucket;
-
- printf("Entries = %ld, hits = %ld, partials = %ld, misses = %ld\n",
- table->entries, table->hits, table->partials, table->misses);
- clear_dist();
- for (i = 0; i < HASH_SIZE; i++) {
- bucket = table->buckets[i];
- update_dist(count_entries(bucket));
- }
- for (i = 0; i < DIST_LIMIT; i++) {
- if (i != DIST_LIMIT-1) printf("%5d %10d\n", i, dist[i]);
- else printf("other %10d\n", dist[i]);
- }
-}
-
-static void check_table(__glxHashTablePtr table,
- unsigned long key, unsigned long value)
-{
- unsigned long retval = 0;
- int retcode = __glxHashLookup(table, key, &retval);
-
- switch (retcode) {
- case -1:
- printf("Bad magic = 0x%08lx:"
- " key = %lu, expected = %lu, returned = %lu\n",
- table->magic, key, value, retval);
- break;
- case 1:
- printf("Not found: key = %lu, expected = %lu returned = %lu\n",
- key, value, retval);
- break;
- case 0:
- if (value != retval)
- printf("Bad value: key = %lu, expected = %lu, returned = %lu\n",
- key, value, retval);
- break;
- default:
- printf("Bad retcode = %d: key = %lu, expected = %lu, returned = %lu\n",
- retcode, key, value, retval);
- break;
- }
-}
-
-int main(void)
-{
- __glxHashTablePtr table;
- int i;
-
- printf("\n***** 256 consecutive integers ****\n");
- table = __glxHashCreate();
- for (i = 0; i < 256; i++) __glxHashInsert(table, i, i);
- for (i = 0; i < 256; i++) check_table(table, i, i);
- for (i = 256; i >= 0; i--) check_table(table, i, i);
- compute_dist(table);
- __glxHashDestroy(table);
-
- printf("\n***** 1024 consecutive integers ****\n");
- table = __glxHashCreate();
- for (i = 0; i < 1024; i++) __glxHashInsert(table, i, i);
- for (i = 0; i < 1024; i++) check_table(table, i, i);
- for (i = 1024; i >= 0; i--) check_table(table, i, i);
- compute_dist(table);
- __glxHashDestroy(table);
-
- printf("\n***** 1024 consecutive page addresses (4k pages) ****\n");
- table = __glxHashCreate();
- for (i = 0; i < 1024; i++) __glxHashInsert(table, i*4096, i);
- for (i = 0; i < 1024; i++) check_table(table, i*4096, i);
- for (i = 1024; i >= 0; i--) check_table(table, i*4096, i);
- compute_dist(table);
- __glxHashDestroy(table);
-
- printf("\n***** 1024 random integers ****\n");
- table = __glxHashCreate();
- srandom(0xbeefbeef);
- for (i = 0; i < 1024; i++) __glxHashInsert(table, random(), i);
- srandom(0xbeefbeef);
- for (i = 0; i < 1024; i++) check_table(table, random(), i);
- srandom(0xbeefbeef);
- for (i = 0; i < 1024; i++) check_table(table, random(), i);
- compute_dist(table);
- __glxHashDestroy(table);
-
- printf("\n***** 5000 random integers ****\n");
- table = __glxHashCreate();
- srandom(0xbeefbeef);
- for (i = 0; i < 5000; i++) __glxHashInsert(table, random(), i);
- srandom(0xbeefbeef);
- for (i = 0; i < 5000; i++) check_table(table, random(), i);
- srandom(0xbeefbeef);
- for (i = 0; i < 5000; i++) check_table(table, random(), i);
- compute_dist(table);
- __glxHashDestroy(table);
-
- return 0;
-}
-#endif
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