Adding upstream version 2.4.114.upstream/2.4.114upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 242 insertions, 0 deletions

diff --git a/xf86drmHash.c b/xf86drmHash.c
new file mode 100644
index 0000000..2cf2b80
--- /dev/null
+++ b/xf86drmHash.c
@@ -0,0 +1,242 @@
+/* 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 "libdrm_macros.h"
+#include "xf86drm.h"
+#include "xf86drmHash.h"
+
+#define HASH_MAGIC 0xdeadbeef
+
+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) {
+	void *state;
+	state = drmRandomCreate(37);
+	for (i = 0; i < 256; i++) scatter[i] = drmRandom(state);
+	drmRandomDestroy(state);
+	++init;
+    }
+
+    while (tmp) {
+	hash = (hash << 1) + scatter[tmp & 0xff];
+	tmp >>= 8;
+    }
+
+    hash %= HASH_SIZE;
+    return hash;
+}
+
+drm_public void *drmHashCreate(void)
+{
+    HashTablePtr table;
+
+    table           = drmMalloc(sizeof(*table));
+    if (!table) return NULL;
+    table->magic    = HASH_MAGIC;
+
+    return table;
+}
+
+drm_public int drmHashDestroy(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;
+	    drmFree(bucket);
+	    bucket = next;
+	}
+    }
+    drmFree(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;
+}
+
+drm_public int drmHashLookup(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 */
+}
+
+drm_public int drmHashInsert(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               = drmMalloc(sizeof(*bucket));
+    if (!bucket) return -1;	/* Error */
+    bucket->key          = key;
+    bucket->value        = value;
+    bucket->next         = table->buckets[hash];
+    table->buckets[hash] = bucket;
+    return 0;			/* Added to table */
+}
+
+drm_public int drmHashDelete(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;
+    drmFree(bucket);
+    return 0;
+}
+
+drm_public int drmHashNext(void *t, unsigned long *key, void **value)
+{
+    HashTablePtr  table = (HashTablePtr)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;
+}
+
+drm_public int drmHashFirst(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 drmHashNext(table, key, value);
+}