297 lines
11 KiB
C
297 lines
11 KiB
C
/* -*-c-*-
|
|
* This file contains the hashing implementation.
|
|
*
|
|
* Copyright (C) 1991 Threaded Technologies Inc.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published
|
|
* by the Free Software Foundation; either version 1, or any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*
|
|
* You should receive a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
*
|
|
$Header: /usr/user/dennis_glatting/ObjC/c-runtime/lib/RCS/hash.c,v 0.8 1991/11/24 01:20:02 dennisg Exp dennisg $
|
|
$Author: dennisg $
|
|
$Date: 1991/11/24 01:20:02 $
|
|
$Log: hash.c,v $
|
|
* Revision 0.8 1991/11/24 01:20:02 dennisg
|
|
* changed shorts back to ints.
|
|
* the efficiency gained didn't out weight the grossness of the code.
|
|
*
|
|
* Revision 0.7 1991/11/23 22:18:29 dennisg
|
|
* deleted hashIndex() and moved it to hash-inline.h
|
|
* converted hash_value_for_key () to a inline and moved it to hash-inline.h.
|
|
*
|
|
* Revision 0.6 1991/11/21 22:27:06 dennisg
|
|
* changed hash value calculation.
|
|
* func name changed from hashValue () to hashIndex(). the
|
|
* func really calculated a index anyway.
|
|
* changed hash func impl. essentially it was calculating a hash value
|
|
* from a hash value. this is a implementation thing.
|
|
*
|
|
* Revision 0.5 1991/11/20 23:29:20 dennisg
|
|
* converted hashIndex() to a inline.
|
|
*
|
|
* Revision 0.4 1991/11/19 12:34:41 dennisg
|
|
* bug in hash_delete (). It was using void* to obtain nodes to
|
|
* pass to hash_remove (). The value passed to hash_removed () is a
|
|
* entry from the node structure rather than the node itself. Using
|
|
* void* removed compiler checking.
|
|
* Modified to implement cache expansion.
|
|
*
|
|
* Revision 0.3 1991/11/07 23:23:40 dennisg
|
|
* implemented hash table expansion as suggested by rms.
|
|
*
|
|
* Revision 0.2 1991/11/07 22:30:54 dennisg
|
|
* added copyleft
|
|
*
|
|
* Revision 0.1 1991/10/24 00:45:39 dennisg
|
|
* Initial check in. Preliminary development stage.
|
|
*
|
|
*/
|
|
|
|
|
|
#include <hash.h>
|
|
#include <hash-inline.h>
|
|
#include <ObjC.h>
|
|
#include <ObjC-private.h>
|
|
|
|
#include <assert.h>
|
|
#include <libc.h>
|
|
#include <math.h>
|
|
|
|
/* These two macros determine
|
|
when a hash table is full and
|
|
by how much it should be
|
|
expanded respectively.
|
|
|
|
These equations are
|
|
percentages. */
|
|
#define FULLNESS(cache) \
|
|
((((cache)->sizeOfHash * 75 ) / 100) <= (cache)->entriesInHash)
|
|
#define EXPANSION(cache) \
|
|
(((cache)->sizeOfHash * 175 ) / 100 )
|
|
|
|
#define MEMORY_ALLOCATION_ADJUST(i) \
|
|
((i&0x01)?i:(i-1))
|
|
|
|
Cache_t hash_new (u_int sizeOfHash) {
|
|
|
|
Cache_t retCache;
|
|
|
|
|
|
assert(sizeOfHash);
|
|
|
|
/* Memory is allocated on this
|
|
machine in even address
|
|
chunks. Therefore the
|
|
modulus must be odd. */
|
|
sizeOfHash = MEMORY_ALLOCATION_ADJUST(sizeOfHash);
|
|
|
|
/* Allocate the cache
|
|
structure. calloc () insures
|
|
its initialization for
|
|
default values. */
|
|
retCache = calloc (1, sizeof (Cache));
|
|
assert(retCache);
|
|
|
|
/* Allocate the array of
|
|
buckets for the cache.
|
|
calloc () initializes all of
|
|
the pointers to NULL. */
|
|
retCache->theNodeTable = calloc (sizeOfHash, sizeof (CacheNode_t));
|
|
assert(retCache->theNodeTable);
|
|
|
|
retCache->sizeOfHash = sizeOfHash;
|
|
|
|
return retCache;
|
|
}
|
|
|
|
|
|
void hash_delete (Cache_t theCache) {
|
|
|
|
CacheNode_t aNode;
|
|
|
|
|
|
/* Purge all key/value pairs
|
|
from the table. */
|
|
while (aNode = hash_next (theCache, NULL))
|
|
hash_remove (theCache, aNode->theKey);
|
|
|
|
/* Release the array of nodes
|
|
and the cache itself. */
|
|
free (theCache->theNodeTable);
|
|
free (theCache);
|
|
}
|
|
|
|
|
|
void hash_add (Cache_t* theCache, void* aKey, void* aValue) {
|
|
|
|
u_int indx = hashIndex(*theCache, aKey);
|
|
CacheNode_t aCacheNode = calloc (1, sizeof (CacheNode));
|
|
|
|
|
|
assert(aCacheNode);
|
|
|
|
/* Initialize the new node. */
|
|
aCacheNode->theKey = aKey;
|
|
aCacheNode->theValue = aValue;
|
|
aCacheNode->nextNode = (* (*theCache)->theNodeTable)[ indx ];
|
|
|
|
/* Debugging.
|
|
|
|
Check the list for another
|
|
key. */
|
|
#ifdef DEBUG
|
|
{ CacheNode_t checkHashNode = (* (*theCache)->theNodeTable)[ indx ];
|
|
|
|
while (checkHashNode) {
|
|
|
|
assert(checkHashNode->theKey != aKey);
|
|
checkHashNode = checkHashNode->nextNode;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* Install the node as the
|
|
first element on the list. */
|
|
(* (*theCache)->theNodeTable)[ indx ] = aCacheNode;
|
|
|
|
/* Bump the number of entries
|
|
in the cache. */
|
|
++ (*theCache)->entriesInHash;
|
|
|
|
/* Check the hash table's
|
|
fullness. We're going
|
|
to expand if it is above
|
|
the fullness level. */
|
|
if (FULLNESS (*theCache)) {
|
|
/* The hash table has reached
|
|
its fullness level. Time to
|
|
expand it.
|
|
|
|
I'm using a slow method
|
|
here but is built on other
|
|
primitive functions thereby
|
|
increasing its
|
|
correctness. */
|
|
CacheNode_t aNode = NULL;
|
|
Cache_t newCache =
|
|
hash_new (MEMORY_ALLOCATION_ADJUST( EXPANSION (*theCache)));
|
|
|
|
DEBUG_PRINTF (stderr, "Expanding cache %#x from %d to %d\n",
|
|
*theCache, (*theCache)->sizeOfHash, newCache->sizeOfHash);
|
|
|
|
/* Copy the nodes from the
|
|
first hash table to the
|
|
new one. */
|
|
while (aNode = hash_next (*theCache, aNode))
|
|
hash_add (&newCache, aNode->theKey, aNode->theValue);
|
|
|
|
/* Trash the old cache. */
|
|
hash_delete (*theCache);
|
|
|
|
/* Return a pointer to the new
|
|
hash table. */
|
|
*theCache = newCache;
|
|
}
|
|
}
|
|
|
|
|
|
void hash_remove (Cache_t theCache, void* aKey) {
|
|
|
|
u_int indx = hashIndex(theCache, aKey);
|
|
CacheNode_t aCacheNode = (*theCache->theNodeTable)[ indx ];
|
|
|
|
|
|
/* We assume there is an entry
|
|
in the table. Error if it
|
|
is not. */
|
|
assert(aCacheNode);
|
|
|
|
/* Special case. First element
|
|
is the key/value pair to be
|
|
removed. */
|
|
if (aCacheNode->theKey == aKey) {
|
|
(*theCache->theNodeTable)[ indx ] = aCacheNode->nextNode;
|
|
free (aCacheNode);
|
|
} else {
|
|
/* Otherwise, find the hash
|
|
entry. */
|
|
CacheNode_t prevHashNode = aCacheNode;
|
|
BOOL removed = NO;
|
|
|
|
do {
|
|
|
|
if (aCacheNode->theKey == aKey) {
|
|
prevHashNode->nextNode = aCacheNode->nextNode, removed = YES;
|
|
free (aCacheNode);
|
|
} else
|
|
prevHashNode = aCacheNode, aCacheNode = aCacheNode->nextNode;
|
|
} while (!removed && aCacheNode);
|
|
assert(removed);
|
|
}
|
|
|
|
/* Decrement the number of
|
|
entries in the hash table. */
|
|
--theCache->entriesInHash;
|
|
}
|
|
|
|
|
|
CacheNode_t hash_next (Cache_t theCache, CacheNode_t aCacheNode) {
|
|
|
|
CacheNode_t theCacheNode = aCacheNode;
|
|
|
|
|
|
/* If the scan is being started
|
|
then reset the last node
|
|
visitied pointer and bucket
|
|
index. */
|
|
if (!theCacheNode)
|
|
theCache->lastBucket = 0;
|
|
|
|
/* If there is a node visited
|
|
last then check for another
|
|
entry in the same bucket;
|
|
Otherwise step to the next
|
|
bucket. */
|
|
if (theCacheNode)
|
|
if (theCacheNode->nextNode)
|
|
/* There is a node which
|
|
follows the last node
|
|
returned. Step to that node
|
|
and retun it. */
|
|
return theCacheNode->nextNode;
|
|
else
|
|
++theCache->lastBucket;
|
|
|
|
/* If the list isn't exhausted
|
|
then search the buckets for
|
|
other nodes. */
|
|
if (theCache->lastBucket < theCache->sizeOfHash) {
|
|
/* Scan the remainder of the
|
|
buckets looking for an entry
|
|
at the head of the list.
|
|
Return the first item
|
|
found. */
|
|
while (theCache->lastBucket < theCache->sizeOfHash)
|
|
if ((*theCache->theNodeTable)[ theCache->lastBucket ])
|
|
return (*theCache->theNodeTable)[ theCache->lastBucket ];
|
|
else
|
|
++theCache->lastBucket;
|
|
|
|
/* No further nodes were found
|
|
in the hash table. */
|
|
return NULL;
|
|
} else
|
|
return NULL;
|
|
}
|
|
|
|
|