--- /dev/null
+/***********************************************************
+* Artsoft Retro-Game Library *
+*----------------------------------------------------------*
+* (c) 1994-2003 Artsoft Entertainment *
+* Holger Schemel *
+* Detmolder Strasse 189 *
+* 33604 Bielefeld *
+* Germany *
+* e-mail: info@artsoft.org *
+*----------------------------------------------------------*
+* hash.c *
+***********************************************************/
+
+/*
+ * Copyright (C) 2002 Christopher Clark <firstname.lastname@cl.cam.ac.uk>
+ *
+ * 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 shall be included in
+ * all copies of the Software and its documentation and acknowledgment shall be
+ * given in the documentation and software packages that this Software was
+ * used.
+ *
+ * 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
+ * THE AUTHORS 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.
+ * */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "hash.h"
+
+
+/*****************************************************************************/
+struct hashtable *
+create_hashtable(unsigned int minsize, float maxloadfactor,
+ unsigned int (*hashf) (void*),
+ int (*eqf) (void*,void*))
+{
+ struct hashtable *h;
+ unsigned int i, size = 1u;
+ /* Check requested hashtable isn't too large */
+ if (minsize > (1u << 31)) return NULL;
+ /* Enforce size as power of 2 */
+ while (size < minsize) size <<= 1;
+ 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*/
+ for (i=0;i<size;i++) { h->table[i] = NULL; }
+ h->tablelength = size;
+ h->entrycount = 0;
+ h->hashfn = hashf;
+ h->eqfn = eqf;
+ h->loadlimit = (unsigned int) ((float)size * maxloadfactor);
+ return h;
+}
+
+/*****************************************************************************/
+static 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 unsigned int
+indexFor(unsigned int tablelength, unsigned int hashvalue)
+{
+ /* Only works if tablelength == 2^N */
+ return (hashvalue & (tablelength - 1u));
+}
+
+/*****************************************************************************/
+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 (0 == (newsize = (h->tablelength << 1))) return 0;
+
+ 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) return 0;
+ h->table = newtable;
+ for (i = h->tablelength; i < newsize; i++) {
+ newtable[i] = NULL;
+ }
+ 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 <<= 1;
+ 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;
+}
+
+/*****************************************************************************/
+int
+hashtable_change(struct hashtable *h, void *k, void *v)
+{
+ 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)))
+ {
+ free(e->v);
+ e->v = v;
+ return -1;
+ }
+ e = e->next;
+ }
+ return 0;
+}
+
+/*****************************************************************************/
+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 index = indexFor(h->tablelength,hash(h,k));
+ pE = &(h->table[index]);
+ e = *pE;
+ while (NULL != e)
+ {
+ if (h->eqfn(k, e->k))
+ {
+ *pE = e->next;
+ h->entrycount--;
+ v = e->v;
+ free(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; free(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; free(f->k); free(f); }
+ }
+ }
+}
+
+
+/*****************************************************************************/
+/* hashtable_iterator - iterator constructor */
+
+struct hashtable_itr *
+hashtable_iterator(struct hashtable *h)
+{
+ unsigned int i, tablelength;
+ struct hashtable_itr *itr = (struct hashtable_itr *)
+ malloc(sizeof(struct hashtable_itr));
+ if (NULL == itr) return NULL;
+ itr->h = h;
+ itr->e = NULL;
+ tablelength = h->tablelength;
+ itr->index = tablelength;
+ if (0 == h->entrycount) return itr;
+
+ for (i = 0; i < tablelength; i++)
+ {
+ if (NULL != h->table[i])
+ {
+ itr->e = h->table[i];
+ itr->index = i;
+ break;
+ }
+ }
+ return itr;
+}
+
+/*****************************************************************************/
+/* key - return the key of the (key,value) pair at the current position */
+
+void *
+hashtable_iterator_key(struct hashtable_itr *i)
+{
+ return i->e->k;
+}
+
+/*****************************************************************************/
+/* value - return the value of the (key,value) pair at the current position */
+
+void *
+hashtable_iterator_value(struct hashtable_itr *i)
+{
+ return i->e->v;
+}
+
+/*****************************************************************************/
+/* advance - advance the iterator to the next element
+ * returns zero if advanced to end of table */
+
+int
+hashtable_iterator_advance(struct hashtable_itr *itr)
+{
+ unsigned int j,tablelength;
+ struct entry **table;
+ struct entry *next;
+ if (NULL == itr->e) return 0; /* stupidity check */
+
+ next = itr->e->next;
+ if (NULL != next)
+ {
+ itr->e = next;
+ return -1;
+ }
+ tablelength = itr->h->tablelength;
+ if (tablelength <= (j = ++(itr->index)))
+ {
+ itr->e = NULL;
+ return 0;
+ }
+ table = itr->h->table;
+ while (NULL == (next = table[j]))
+ {
+ if (++j >= tablelength)
+ {
+ itr->index = tablelength;
+ return 0;
+ }
+ }
+ itr->index = j;
+ itr->e = next;
+ return -1;
+}
projects / rocksndiamonds.git / blobdiff