/* $NetBSD: hash.c,v 1.5 2007/03/03 00:09:30 simonb Exp $ */
/*
* Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Adam de Boor.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*/
/*
* Copyright (c) 1988, 1989 by Adam de Boor
* Copyright (c) 1989 by Berkeley Softworks
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Adam de Boor.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*/
#ifdef MAKE_BOOTSTRAP
static char rcsid[] = "$NetBSD: hash.c,v 1.5 2007/03/03 00:09:30 simonb Exp $";
#else
#include
#ifndef lint
#if 0
static char sccsid[] = "@(#)hash.c 8.1 (Berkeley) 6/6/93";
#else
__RCSID("$NetBSD: hash.c,v 1.5 2007/03/03 00:09:30 simonb Exp $");
#endif
#endif /* not lint */
#endif
#include
#include
#include
#include
#include
#include
/* hash.c --
*
* This module contains routines to manipulate a hash table.
* See hash.h for a definition of the structure of the hash
* table. Hash tables grow automatically as the amount of
* information increases.
*/
#include "hash.h"
/*
* Forward references to local procedures that are used before they're
* defined:
*/
static void RebuildTable(Hash_Table *);
/*
* The following defines the ratio of # entries to # buckets
* at which we rebuild the table to make it larger.
*/
#define rebuildLimit 8
/*
*---------------------------------------------------------
*
* Hash_InitTable --
*
* This routine just sets up the hash table.
*
* Input:
* t Structure to use to hold table.
* numBuckets How many buckets to create for starters. This number
* is rounded up to a power of two. If <= 0, a reasonable
* default is chosen. The table will grow in size later
* as needed.
*
* Results:
* None.
*
* Side Effects:
* Memory is allocated for the initial bucket area.
*
*---------------------------------------------------------
*/
void
Hash_InitTable(Hash_Table *t, int numBuckets)
{
int i;
struct Hash_Entry **hp;
/*
* Round up the size to a power of two.
*/
if (numBuckets <= 0)
i = 16;
else {
for (i = 2; i < numBuckets; i <<= 1)
continue;
}
t->numEntries = 0;
t->size = i;
t->mask = i - 1;
t->bucketPtr = hp = (struct Hash_Entry **)emalloc(sizeof(*hp) * i);
while (--i >= 0)
*hp++ = NULL;
}
/*
*---------------------------------------------------------
*
* Hash_DeleteTable --
*
* This routine removes everything from a hash table
* and frees up the memory space it occupied (except for
* the space in the Hash_Table structure).
*
* Results:
* None.
*
* Side Effects:
* Lots of memory is freed up.
*
*---------------------------------------------------------
*/
void
Hash_DeleteTable(Hash_Table *t)
{
struct Hash_Entry **hp, *h, *nexth;
int i;
nexth = NULL;
for (hp = t->bucketPtr, i = t->size; --i >= 0;) {
for (h = *hp++; h != NULL; h = nexth) {
nexth = h->next;
free(h);
}
}
free(t->bucketPtr);
/*
* Set up the hash table to cause memory faults on any future access
* attempts until re-initialization.
*/
t->bucketPtr = NULL;
}
/*
*---------------------------------------------------------
*
* Hash_FindEntry --
*
* Searches a hash table for an entry corresponding to key.
*
* Input:
* t Hash table to search.
* key A hash key.
*
* Results:
* The return value is a pointer to the entry for key,
* if key was present in the table. If key was not
* present, NULL is returned.
*
* Side Effects:
* None.
*
*---------------------------------------------------------
*/
Hash_Entry *
Hash_FindEntry(Hash_Table *t, char *key)
{
Hash_Entry *e;
unsigned h;
char *p;
for (h = 0, p = key; *p;)
h = (h << 5) - h + *p++;
p = key;
for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next)
if (e->namehash == h && strcmp(e->name, p) == 0)
return (e);
return (NULL);
}
/*
*---------------------------------------------------------
*
* Hash_CreateEntry --
*
* Searches a hash table for an entry corresponding to
* key. If no entry is found, then one is created.
*
* Input:
* t Hash table to search.
* key A hash key.
* newPtr Filled in with 1 if new entry created, 0 otherwise.
*
* Results:
* The return value is a pointer to the entry. If *newPtr
* isn't NULL, then *newPtr is filled in with TRUE if a
* new entry was created, and FALSE if an entry already existed
* with the given key.
*
* Side Effects:
* Memory may be allocated, and the hash buckets may be modified.
*---------------------------------------------------------
*/
Hash_Entry *
Hash_CreateEntry(Hash_Table *t, char *key, int *newPtr)
{
Hash_Entry *e;
unsigned h;
char *p;
int keylen;
struct Hash_Entry **hp;
/*
* Hash the key. As a side effect, save the length (strlen) of the
* key in case we need to create the entry.
*/
for (h = 0, p = key; *p;)
h = (h << 5) - h + *p++;
keylen = p - key;
p = key;
for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) {
if (e->namehash == h && strcmp(e->name, p) == 0) {
if (newPtr != NULL)
*newPtr = 0;
return (e);
}
}
/*
* The desired entry isn't there. Before allocating a new entry,
* expand the table if necessary (and this changes the resulting
* bucket chain).
*/
if (t->numEntries >= rebuildLimit * t->size)
RebuildTable(t);
e = (Hash_Entry *) emalloc(sizeof(*e) + keylen);
hp = &t->bucketPtr[h & t->mask];
e->next = *hp;
*hp = e;
e->clientData = NULL;
e->namehash = h;
(void) strcpy(e->name, p);
t->numEntries++;
if (newPtr != NULL)
*newPtr = 1;
return (e);
}
/*
*---------------------------------------------------------
*
* Hash_DeleteEntry --
*
* Delete the given hash table entry and free memory associated with
* it.
*
* Results:
* None.
*
* Side Effects:
* Hash chain that entry lives in is modified and memory is freed.
*
*---------------------------------------------------------
*/
void
Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e)
{
Hash_Entry **hp, *p;
if (e == NULL)
return;
for (hp = &t->bucketPtr[e->namehash & t->mask];
(p = *hp) != NULL; hp = &p->next) {
if (p == e) {
*hp = p->next;
free(p);
t->numEntries--;
return;
}
}
(void)write(2, "bad call to Hash_DeleteEntry\n", 29);
abort();
}
/*
*---------------------------------------------------------
*
* Hash_EnumFirst --
* This procedure sets things up for a complete search
* of all entries recorded in the hash table.
*
* Input:
* t Table to be searched.
* searchPtr Area in which to keep state about search.
*
* Results:
* The return value is the address of the first entry in
* the hash table, or NULL if the table is empty.
*
* Side Effects:
* The information in searchPtr is initialized so that successive
* calls to Hash_Next will return successive HashEntry's
* from the table.
*
*---------------------------------------------------------
*/
Hash_Entry *
Hash_EnumFirst(Hash_Table *t, Hash_Search *searchPtr)
{
searchPtr->tablePtr = t;
searchPtr->nextIndex = 0;
searchPtr->hashEntryPtr = NULL;
return Hash_EnumNext(searchPtr);
}
/*
*---------------------------------------------------------
*
* Hash_EnumNext --
* This procedure returns successive entries in the hash table.
*
* Results:
* The return value is a pointer to the next HashEntry
* in the table, or NULL when the end of the table is
* reached.
*
* Side Effects:
* The information in searchPtr is modified to advance to the
* next entry.
*
*---------------------------------------------------------
*/
Hash_Entry *
Hash_EnumNext(Hash_Search *searchPtr)
{
Hash_Entry *e;
Hash_Table *t = searchPtr->tablePtr;
/*
* The hashEntryPtr field points to the most recently returned
* entry, or is nil if we are starting up. If not nil, we have
* to start at the next one in the chain.
*/
e = searchPtr->hashEntryPtr;
if (e != NULL)
e = e->next;
/*
* If the chain ran out, or if we are starting up, we need to
* find the next nonempty chain.
*/
while (e == NULL) {
if (searchPtr->nextIndex >= t->size)
return (NULL);
e = t->bucketPtr[searchPtr->nextIndex++];
}
searchPtr->hashEntryPtr = e;
return (e);
}
/*
*---------------------------------------------------------
*
* RebuildTable --
* This local routine makes a new hash table that
* is larger than the old one.
*
* Results:
* None.
*
* Side Effects:
* The entire hash table is moved, so any bucket numbers
* from the old table are invalid.
*
*---------------------------------------------------------
*/
static void
RebuildTable(Hash_Table *t)
{
Hash_Entry *e, *next, **hp, **xp;
int i, mask;
Hash_Entry **oldhp;
int oldsize;
next = NULL;
oldhp = t->bucketPtr;
oldsize = i = t->size;
i <<= 1;
t->size = i;
t->mask = mask = i - 1;
t->bucketPtr = hp = (struct Hash_Entry **) emalloc(sizeof(*hp) * i);
while (--i >= 0)
*hp++ = NULL;
for (hp = oldhp, i = oldsize; --i >= 0;) {
for (e = *hp++; e != NULL; e = next) {
next = e->next;
xp = &t->bucketPtr[e->namehash & mask];
e->next = *xp;
*xp = e;
}
}
free(oldhp);
}