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-rw-r--r--mkfs.ubifs/hashtable/hashtable.c274
1 files changed, 274 insertions, 0 deletions
diff --git a/mkfs.ubifs/hashtable/hashtable.c b/mkfs.ubifs/hashtable/hashtable.c
new file mode 100644
index 0000000..763357e
--- /dev/null
+++ b/mkfs.ubifs/hashtable/hashtable.c
@@ -0,0 +1,274 @@
+/* Copyright (C) 2004 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */
+
+#include "hashtable.h"
+#include "hashtable_private.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+
+/*
+Credit for primes table: Aaron Krowne
+ http://br.endernet.org/~akrowne/
+ http://planetmath.org/encyclopedia/GoodHashTablePrimes.html
+*/
+static const unsigned int primes[] = {
+53, 97, 193, 389,
+769, 1543, 3079, 6151,
+12289, 24593, 49157, 98317,
+196613, 393241, 786433, 1572869,
+3145739, 6291469, 12582917, 25165843,
+50331653, 100663319, 201326611, 402653189,
+805306457, 1610612741
+};
+const unsigned int prime_table_length = sizeof(primes)/sizeof(primes[0]);
+const float max_load_factor = 0.65;
+
+/*****************************************************************************/
+struct hashtable *
+create_hashtable(unsigned int minsize,
+ unsigned int (*hashf) (void*),
+ int (*eqf) (void*,void*))
+{
+ struct hashtable *h;
+ unsigned int pindex, size = primes[0];
+ /* Check requested hashtable isn't too large */
+ if (minsize > (1u << 30)) return NULL;
+ /* Enforce size as prime */
+ for (pindex=0; pindex < prime_table_length; pindex++) {
+ if (primes[pindex] > minsize) { size = primes[pindex]; break; }
+ }
+ h = (struct hashtable *)malloc(sizeof(struct hashtable));
+ if (NULL == h) return NULL; /*oom*/
+ h->table = (struct entry **)malloc(sizeof(struct entry*) * size);
+ if (NULL == h->table) { free(h); return NULL; } /*oom*/
+ memset(h->table, 0, size * sizeof(struct entry *));
+ h->tablelength = size;
+ h->primeindex = pindex;
+ h->entrycount = 0;
+ h->hashfn = hashf;
+ h->eqfn = eqf;
+ h->loadlimit = (unsigned int) ceil(size * max_load_factor);
+ return h;
+}
+
+/*****************************************************************************/
+unsigned int
+hash(struct hashtable *h, void *k)
+{
+ /* Aim to protect against poor hash functions by adding logic here
+ * - logic taken from java 1.4 hashtable source */
+ unsigned int i = h->hashfn(k);
+ i += ~(i << 9);
+ i ^= ((i >> 14) | (i << 18)); /* >>> */
+ i += (i << 4);
+ i ^= ((i >> 10) | (i << 22)); /* >>> */
+ return i;
+}
+
+/*****************************************************************************/
+static int
+hashtable_expand(struct hashtable *h)
+{
+ /* Double the size of the table to accomodate more entries */
+ struct entry **newtable;
+ struct entry *e;
+ struct entry **pE;
+ unsigned int newsize, i, index;
+ /* Check we're not hitting max capacity */
+ if (h->primeindex == (prime_table_length - 1)) return 0;
+ newsize = primes[++(h->primeindex)];
+
+ newtable = (struct entry **)malloc(sizeof(struct entry*) * newsize);
+ if (NULL != newtable)
+ {
+ memset(newtable, 0, newsize * sizeof(struct entry *));
+ /* This algorithm is not 'stable'. ie. it reverses the list
+ * when it transfers entries between the tables */
+ for (i = 0; i < h->tablelength; i++) {
+ while (NULL != (e = h->table[i])) {
+ h->table[i] = e->next;
+ index = indexFor(newsize,e->h);
+ e->next = newtable[index];
+ newtable[index] = e;
+ }
+ }
+ free(h->table);
+ h->table = newtable;
+ }
+ /* Plan B: realloc instead */
+ else
+ {
+ newtable = (struct entry **)
+ realloc(h->table, newsize * sizeof(struct entry *));
+ if (NULL == newtable) { (h->primeindex)--; return 0; }
+ h->table = newtable;
+ memset(newtable[h->tablelength], 0, newsize - h->tablelength);
+ for (i = 0; i < h->tablelength; i++) {
+ for (pE = &(newtable[i]), e = *pE; e != NULL; e = *pE) {
+ index = indexFor(newsize,e->h);
+ if (index == i)
+ {
+ pE = &(e->next);
+ }
+ else
+ {
+ *pE = e->next;
+ e->next = newtable[index];
+ newtable[index] = e;
+ }
+ }
+ }
+ }
+ h->tablelength = newsize;
+ h->loadlimit = (unsigned int) ceil(newsize * max_load_factor);
+ return -1;
+}
+
+/*****************************************************************************/
+unsigned int
+hashtable_count(struct hashtable *h)
+{
+ return h->entrycount;
+}
+
+/*****************************************************************************/
+int
+hashtable_insert(struct hashtable *h, void *k, void *v)
+{
+ /* This method allows duplicate keys - but they shouldn't be used */
+ unsigned int index;
+ struct entry *e;
+ if (++(h->entrycount) > h->loadlimit)
+ {
+ /* Ignore the return value. If expand fails, we should
+ * still try cramming just this value into the existing table
+ * -- we may not have memory for a larger table, but one more
+ * element may be ok. Next time we insert, we'll try expanding again.*/
+ hashtable_expand(h);
+ }
+ e = (struct entry *)malloc(sizeof(struct entry));
+ if (NULL == e) { --(h->entrycount); return 0; } /*oom*/
+ e->h = hash(h,k);
+ index = indexFor(h->tablelength,e->h);
+ e->k = k;
+ e->v = v;
+ e->next = h->table[index];
+ h->table[index] = e;
+ return -1;
+}
+
+/*****************************************************************************/
+void * /* returns value associated with key */
+hashtable_search(struct hashtable *h, void *k)
+{
+ struct entry *e;
+ unsigned int hashvalue, index;
+ hashvalue = hash(h,k);
+ index = indexFor(h->tablelength,hashvalue);
+ e = h->table[index];
+ while (NULL != e)
+ {
+ /* Check hash value to short circuit heavier comparison */
+ if ((hashvalue == e->h) && (h->eqfn(k, e->k))) return e->v;
+ e = e->next;
+ }
+ return NULL;
+}
+
+/*****************************************************************************/
+void * /* returns value associated with key */
+hashtable_remove(struct hashtable *h, void *k)
+{
+ /* TODO: consider compacting the table when the load factor drops enough,
+ * or provide a 'compact' method. */
+
+ struct entry *e;
+ struct entry **pE;
+ void *v;
+ unsigned int hashvalue, index;
+
+ hashvalue = hash(h,k);
+ index = indexFor(h->tablelength,hash(h,k));
+ pE = &(h->table[index]);
+ e = *pE;
+ while (NULL != e)
+ {
+ /* Check hash value to short circuit heavier comparison */
+ if ((hashvalue == e->h) && (h->eqfn(k, e->k)))
+ {
+ *pE = e->next;
+ h->entrycount--;
+ v = e->v;
+ freekey(e->k);
+ free(e);
+ return v;
+ }
+ pE = &(e->next);
+ e = e->next;
+ }
+ return NULL;
+}
+
+/*****************************************************************************/
+/* destroy */
+void
+hashtable_destroy(struct hashtable *h, int free_values)
+{
+ unsigned int i;
+ struct entry *e, *f;
+ struct entry **table = h->table;
+ if (free_values)
+ {
+ for (i = 0; i < h->tablelength; i++)
+ {
+ e = table[i];
+ while (NULL != e)
+ { f = e; e = e->next; freekey(f->k); free(f->v); free(f); }
+ }
+ }
+ else
+ {
+ for (i = 0; i < h->tablelength; i++)
+ {
+ e = table[i];
+ while (NULL != e)
+ { f = e; e = e->next; freekey(f->k); free(f); }
+ }
+ }
+ free(h->table);
+ free(h);
+}
+
+/*
+ * Copyright (c) 2002, Christopher Clark
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the original author; nor the names of any contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
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