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| -rw-r--r-- | tests/hash.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/tests/hash.c b/tests/hash.c new file mode 100644 index 0000000..4475fba --- /dev/null +++ b/tests/hash.c @@ -0,0 +1,217 @@ +/* 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. + * + */ + +#include <stdio.h> +#include <stdlib.h> + +#include "xf86drm.h" +#include "xf86drmHash.h" + +#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 int check_table(HashTablePtr table, + unsigned long key, void * value) +{ + void *retval; + int retcode = drmHashLookup(table, key, &retval); + + switch (retcode) { + case -1: + printf("Bad magic = 0x%08lx:" + " key = %lu, expected = %p, returned = %p\n", + table->magic, key, value, retval); + break; + case 1: + printf("Not found: key = %lu, expected = %p, returned = %p\n", + key, value, retval); + break; + case 0: + if (value != retval) { + printf("Bad value: key = %lu, expected = %p, returned = %p\n", + key, value, retval); + retcode = -1; + } + break; + default: + printf("Bad retcode = %d: key = %lu, expected = %p, returned = %p\n", + retcode, key, value, retval); + break; + } + return retcode; +} + +int main(void) +{ + HashTablePtr table; + unsigned long i; + int ret = 0; + + printf("\n***** 256 consecutive integers ****\n"); + table = drmHashCreate(); + for (i = 0; i < 256; i++) + drmHashInsert(table, i, (void *)(i << 16 | i)); + for (i = 0; i < 256; i++) + ret |= check_table(table, i, (void *)(i << 16 | i)); + compute_dist(table); + drmHashDestroy(table); + + printf("\n***** 1024 consecutive integers ****\n"); + table = drmHashCreate(); + for (i = 0; i < 1024; i++) + drmHashInsert(table, i, (void *)(i << 16 | i)); + for (i = 0; i < 1024; i++) + ret |= check_table(table, i, (void *)(i << 16 | i)); + compute_dist(table); + drmHashDestroy(table); + + printf("\n***** 1024 consecutive page addresses (4k pages) ****\n"); + table = drmHashCreate(); + for (i = 0; i < 1024; i++) + drmHashInsert(table, i*4096, (void *)(i << 16 | i)); + for (i = 0; i < 1024; i++) + ret |= check_table(table, i*4096, (void *)(i << 16 | i)); + compute_dist(table); + drmHashDestroy(table); + + printf("\n***** 1024 random integers ****\n"); + table = drmHashCreate(); + srandom(0xbeefbeef); + for (i = 0; i < 1024; i++) + drmHashInsert(table, random(), (void *)(i << 16 | i)); + srandom(0xbeefbeef); + for (i = 0; i < 1024; i++) + ret |= check_table(table, random(), (void *)(i << 16 | i)); + srandom(0xbeefbeef); + for (i = 0; i < 1024; i++) + ret |= check_table(table, random(), (void *)(i << 16 | i)); + compute_dist(table); + drmHashDestroy(table); + + printf("\n***** 5000 random integers ****\n"); + table = drmHashCreate(); + srandom(0xbeefbeef); + for (i = 0; i < 5000; i++) + drmHashInsert(table, random(), (void *)(i << 16 | i)); + srandom(0xbeefbeef); + for (i = 0; i < 5000; i++) + ret |= check_table(table, random(), (void *)(i << 16 | i)); + srandom(0xbeefbeef); + for (i = 0; i < 5000; i++) + ret |= check_table(table, random(), (void *)(i << 16 | i)); + compute_dist(table); + drmHashDestroy(table); + + return ret; +} |