433 lines
12 KiB
C
433 lines
12 KiB
C
/* xf86drmHash.c -- Small hash table support for integer -> integer mapping
|
|
* Created: Sun Apr 18 09:35:45 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 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.
|
|
*
|
|
*/
|
|
|
|
#ifdef HAVE_XORG_CONFIG_H
|
|
#include <xorg-config.h>
|
|
#endif
|
|
|
|
#define HASH_MAIN 0
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#if !HASH_MAIN
|
|
# include "drm.h"
|
|
# include "xf86drm.h"
|
|
# include "xf86.h"
|
|
#endif
|
|
|
|
#define N(x) drm##x
|
|
|
|
#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! */
|
|
|
|
#if HASH_MAIN
|
|
#define HASH_ALLOC malloc
|
|
#define HASH_FREE free
|
|
#define HASH_RANDOM_DECL
|
|
#define HASH_RANDOM_INIT(seed) srandom(seed)
|
|
#define HASH_RANDOM random()
|
|
#else
|
|
#define HASH_ALLOC drmMalloc
|
|
#define HASH_FREE drmFree
|
|
#define HASH_RANDOM_DECL void *state
|
|
#define HASH_RANDOM_INIT(seed) state = drmRandomCreate(seed)
|
|
#define HASH_RANDOM drmRandom(state)
|
|
|
|
#endif
|
|
|
|
typedef struct HashBucket {
|
|
unsigned long key;
|
|
void *value;
|
|
struct HashBucket *next;
|
|
} HashBucket, *HashBucketPtr;
|
|
|
|
typedef struct HashTable {
|
|
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 */
|
|
HashBucketPtr buckets[HASH_SIZE];
|
|
int p0;
|
|
HashBucketPtr p1;
|
|
} HashTable, *HashTablePtr;
|
|
|
|
#if HASH_MAIN
|
|
extern void *N(HashCreate)(void);
|
|
extern int N(HashDestroy)(void *t);
|
|
extern int N(HashLookup)(void *t, unsigned long key, unsigned long *value);
|
|
extern int N(HashInsert)(void *t, unsigned long key, unsigned long value);
|
|
extern int N(HashDelete)(void *t, unsigned long key);
|
|
#endif
|
|
|
|
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;
|
|
++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;
|
|
}
|
|
|
|
void *N(HashCreate)(void)
|
|
{
|
|
HashTablePtr 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;
|
|
}
|
|
|
|
int N(HashDestroy)(void *t)
|
|
{
|
|
HashTablePtr table = (HashTablePtr)t;
|
|
HashBucketPtr bucket;
|
|
HashBucketPtr 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 HashBucketPtr HashFind(HashTablePtr table,
|
|
unsigned long key, unsigned long *h)
|
|
{
|
|
unsigned long hash = HashHash(key);
|
|
HashBucketPtr prev = NULL;
|
|
HashBucketPtr 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;
|
|
}
|
|
|
|
int N(HashLookup)(void *t, unsigned long key, void **value)
|
|
{
|
|
HashTablePtr table = (HashTablePtr)t;
|
|
HashBucketPtr 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 */
|
|
}
|
|
|
|
int N(HashInsert)(void *t, unsigned long key, void *value)
|
|
{
|
|
HashTablePtr table = (HashTablePtr)t;
|
|
HashBucketPtr 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 */
|
|
}
|
|
|
|
int N(HashDelete)(void *t, unsigned long key)
|
|
{
|
|
HashTablePtr table = (HashTablePtr)t;
|
|
unsigned long hash;
|
|
HashBucketPtr 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;
|
|
}
|
|
|
|
int N(HashNext)(void *t, unsigned long *key, void **value)
|
|
{
|
|
HashTablePtr table = (HashTablePtr)t;
|
|
|
|
for (; table->p0 < HASH_SIZE;
|
|
++table->p0, table->p1 = table->buckets[table->p0]) {
|
|
if (table->p1) {
|
|
*key = table->p1->key;
|
|
*value = table->p1->value;
|
|
table->p1 = table->p1->next;
|
|
return 1;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int N(HashFirst)(void *t, unsigned long *key, void **value)
|
|
{
|
|
HashTablePtr table = (HashTablePtr)t;
|
|
|
|
if (table->magic != HASH_MAGIC) return -1; /* Bad magic */
|
|
|
|
table->p0 = 0;
|
|
table->p1 = table->buckets[0];
|
|
return N(HashNext)(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(HashBucketPtr 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(HashTablePtr table)
|
|
{
|
|
int i;
|
|
HashBucketPtr 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(HashTablePtr table,
|
|
unsigned long key, unsigned long value)
|
|
{
|
|
unsigned long retval = 0;
|
|
int retcode = N(HashLookup)(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)
|
|
{
|
|
HashTablePtr table;
|
|
int i;
|
|
|
|
printf("\n***** 256 consecutive integers ****\n");
|
|
table = N(HashCreate)();
|
|
for (i = 0; i < 256; i++) N(HashInsert)(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);
|
|
N(HashDestroy)(table);
|
|
|
|
printf("\n***** 1024 consecutive integers ****\n");
|
|
table = N(HashCreate)();
|
|
for (i = 0; i < 1024; i++) N(HashInsert)(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);
|
|
N(HashDestroy)(table);
|
|
|
|
printf("\n***** 1024 consecutive page addresses (4k pages) ****\n");
|
|
table = N(HashCreate)();
|
|
for (i = 0; i < 1024; i++) N(HashInsert)(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);
|
|
N(HashDestroy)(table);
|
|
|
|
printf("\n***** 1024 random integers ****\n");
|
|
table = N(HashCreate)();
|
|
srandom(0xbeefbeef);
|
|
for (i = 0; i < 1024; i++) N(HashInsert)(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);
|
|
N(HashDestroy)(table);
|
|
|
|
printf("\n***** 5000 random integers ****\n");
|
|
table = N(HashCreate)();
|
|
srandom(0xbeefbeef);
|
|
for (i = 0; i < 5000; i++) N(HashInsert)(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);
|
|
N(HashDestroy)(table);
|
|
|
|
return 0;
|
|
}
|
|
#endif
|