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/* Copyright (c) 2000 Shlomi Fish
*
* 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 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 THE AUTHORS OR COPYRIGHT
* HOLDERS 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.
*/
/*
* fcs_hash.c - an implementation of a simplistic (keys only) hash. This
* hash uses chaining and re-hashing and was found to be very fast. Not all
* of the functions of the hash ADT are implemented, but it is useful enough
* for Freecell Solver.
*
*/
#define BUILDING_DLL 1
#include "config.h"
#if (FCS_STATE_STORAGE == FCS_STATE_STORAGE_INTERNAL_HASH) || (defined(INDIRECT_STACK_STATES) && (FCS_STACK_STORAGE == FCS_STACK_STORAGE_INTERNAL_HASH))
#include <stdlib.h>
#include <string.h>
#include "fcs_hash.h"
#include "alloc.h"
#include "inline.h"
static void GCC_INLINE fc_solve_hash_rehash(fc_solve_hash_t * hash);
void fc_solve_hash_init(
fc_solve_hash_t * hash,
fc_solve_hash_value_t wanted_size,
#ifdef FCS_WITH_CONTEXT_VARIABLE
int (*compare_function)(const void * key1, const void * key2, void * context),
void * context
#else
int (*compare_function)(const void * key1, const void * key2)
#endif
)
{
int size;
/* Find a size that's a power of 2 that's just greater than
* the wanted_size. */
size = 256;
while (size < wanted_size)
{
size <<= 1;
}
hash->size = size;
hash->size_bitmask = size-1;
hash->num_elems = 0;
/* Allocate a table of size entries */
hash->entries = (fc_solve_hash_symlink_t *)malloc(
sizeof(fc_solve_hash_symlink_t) * size
);
hash->compare_function = compare_function;
#ifdef FCS_WITH_CONTEXT_VARIABLE
hash->context = context;
#endif
/* Initialize all the cells of the hash table to NULL, which indicate
that the cork of the linked list is right at the start */
memset(hash->entries, 0, sizeof(fc_solve_hash_symlink_t)*size);
fc_solve_compact_allocator_init(&(hash->allocator));
return;
}
int fc_solve_hash_insert(
fc_solve_hash_t * hash,
void * key,
void * val,
void * * existing_key,
void * * existing_val,
fc_solve_hash_value_t hash_value
#ifdef FCS_ENABLE_SECONDARY_HASH_VALUE
, fc_solve_hash_value_t secondary_hash_value
#endif
)
{
int place;
fc_solve_hash_symlink_t * list;
fc_solve_hash_symlink_item_t * item, * last_item;
fc_solve_hash_symlink_item_t * * item_placeholder;
/* Get the index of the appropriate chain in the hash table */
place = hash_value & (hash->size_bitmask);
list = &(hash->entries[place]);
/* If first_item is non-existent */
if (list->first_item == NULL)
{
/* Allocate a first item with that key/val pair */
item_placeholder = &(list->first_item);
goto alloc_item;
}
/* Initialize item to the chain's first_item */
item = list->first_item;
last_item = NULL;
while (item != NULL)
{
/*
We first compare the hash values, because it is faster than
comparing the entire data structure.
*/
if (
(item->hash_value == hash_value) &&
#ifdef FCS_ENABLE_SECONDARY_HASH_VALUE
(item->secondary_hash_value == secondary_hash_value) &&
#endif
(!(hash->compare_function(item->key, key
#ifdef FCS_WITH_CONTEXT_VARIABLE
, hash->context
#endif
)))
)
{
*existing_key = item->key;
*existing_val = item->val;
return 1;
}
/* Cache the item before the current in last_item */
last_item = item;
/* Move to the next item */
item = item->next;
}
item_placeholder = &(last_item->next);
alloc_item:
/* Put the new element at the end of the list */
item = *(item_placeholder) = fcs_compact_alloc_ptr(&(hash->allocator), sizeof(*item));
item->next = NULL;
item->key = key;
item->val = val;
item->hash_value = hash_value;
#ifdef FCS_ENABLE_SECONDARY_HASH_VALUE
item->secondary_hash_value = secondary_hash_value;
#endif
if ((++hash->num_elems) > ((hash->size*3)>>2))
{
fc_solve_hash_rehash(hash);
}
*existing_key = NULL;
*existing_val = NULL;
return 0;
}
/*
This function "rehashes" a hash. I.e: it increases the size of its
hash table, allowing for smaller chains, and faster lookup.
*/
static void GCC_INLINE fc_solve_hash_rehash(
fc_solve_hash_t * hash
)
{
int old_size, new_size, new_size_bitmask;
int i;
fc_solve_hash_symlink_item_t * item, * next_item;
int place;
fc_solve_hash_symlink_t * new_entries;
old_size = hash->size;
new_size = old_size << 1;
new_size_bitmask = new_size - 1;
new_entries = calloc(new_size, sizeof(fc_solve_hash_symlink_t));
/* Copy the items to the new hash while not allocating them again */
for(i=0;i<old_size;i++)
{
item = hash->entries[i].first_item;
/* traverse the chain item by item */
while(item != NULL)
{
/* The place in the new hash table */
place = item->hash_value & new_size_bitmask;
/* Store the next item in the linked list in a safe place,
so we can retrieve it after the assignment */
next_item = item->next;
/* It is placed in front of the first element in the chain,
so it should link to it */
item->next = new_entries[place].first_item;
/* Make it the first item in its chain */
new_entries[place].first_item = item;
/* Move to the next item this one. */
item = next_item;
}
};
/* Free the entries of the old hash */
free(hash->entries);
/* Copy the new hash to the old one */
hash->entries = new_entries;
hash->size = new_size;
hash->size_bitmask = new_size_bitmask;
}
#else
/* ANSI C doesn't allow empty compilation */
static void fc_solve_hash_c_dummy();
#endif /* (FCS_STATE_STORAGE == FCS_STATE_STORAGE_INTERNAL_HASH) || defined(INDIRECT_STACK_STATES) */
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