8c087d1a43
documentation already adequatedly existed in the description in most cases. Where it did not, it was added. If no documentation existed beforehand, then none was added. Some unused dummies for use in the traversal functions were marked as __unused during the conversion. Occasionally, local style fixes were applied to lines already being modified or influenced. Now make(1) should always build with WARNS=3.
404 lines
9.9 KiB
C
404 lines
9.9 KiB
C
/*
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* Copyright (c) 1988, 1989, 1990, 1993
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* The Regents of the University of California. All rights reserved.
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* Copyright (c) 1988, 1989 by Adam de Boor
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* Copyright (c) 1989 by Berkeley Softworks
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Adam de Boor.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)hash.c 8.1 (Berkeley) 6/6/93
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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/* hash.c --
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*
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* This module contains routines to manipulate a hash table.
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* See hash.h for a definition of the structure of the hash
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* table. Hash tables grow automatically as the amount of
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* information increases.
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*/
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#include <unistd.h>
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#include "sprite.h"
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#include "make.h"
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#include "hash.h"
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/*
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* Forward references to local procedures that are used before they're
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* defined:
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*/
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static void RebuildTable(Hash_Table *);
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/*
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* The following defines the ratio of # entries to # buckets
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* at which we rebuild the table to make it larger.
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*/
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#define rebuildLimit 8
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/*
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*---------------------------------------------------------
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*
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* Hash_InitTable --
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*
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* Set up the hash table t with a given number of buckets, or a
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* reasonable default if the number requested is less than or
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* equal to zero. Hash tables will grow in size as needed.
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*
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*
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* Results:
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* None.
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*
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* Side Effects:
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* Memory is allocated for the initial bucket area.
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*
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*---------------------------------------------------------
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*/
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void
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Hash_InitTable(Hash_Table *t, int numBuckets)
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{
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int i;
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struct Hash_Entry **hp;
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/*
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* Round up the size to a power of two.
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*/
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if (numBuckets <= 0)
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i = 16;
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else {
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for (i = 2; i < numBuckets; i <<= 1)
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continue;
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}
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t->numEntries = 0;
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t->size = i;
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t->mask = i - 1;
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t->bucketPtr = hp = (struct Hash_Entry **)emalloc(sizeof(*hp) * i);
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while (--i >= 0)
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*hp++ = NULL;
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}
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/*
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*---------------------------------------------------------
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*
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* Hash_DeleteTable --
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*
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* This routine removes everything from a hash table
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* and frees up the memory space it occupied (except for
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* the space in the Hash_Table structure).
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*
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* Results:
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* None.
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*
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* Side Effects:
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* Lots of memory is freed up.
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*
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*---------------------------------------------------------
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*/
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void
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Hash_DeleteTable(Hash_Table *t)
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{
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struct Hash_Entry **hp, *h, *nexth = NULL;
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int i;
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for (hp = t->bucketPtr, i = t->size; --i >= 0;) {
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for (h = *hp++; h != NULL; h = nexth) {
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nexth = h->next;
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free((char *)h);
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}
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}
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free((char *)t->bucketPtr);
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/*
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* Set up the hash table to cause memory faults on any future access
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* attempts until re-initialization.
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*/
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t->bucketPtr = NULL;
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}
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/*
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*---------------------------------------------------------
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*
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* Hash_FindEntry --
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*
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* Searches a hash table for an entry corresponding to key.
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*
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* Results:
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* The return value is a pointer to the entry for key,
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* if key was present in the table. If key was not
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* present, NULL is returned.
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*
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* Side Effects:
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* None.
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*
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*---------------------------------------------------------
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*/
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Hash_Entry *
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Hash_FindEntry(Hash_Table *t, char *key)
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{
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Hash_Entry *e;
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unsigned h;
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char *p;
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for (h = 0, p = key; *p;)
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h = (h << 5) - h + *p++;
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p = key;
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for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next)
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if (e->namehash == h && strcmp(e->name, p) == 0)
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return (e);
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return (NULL);
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}
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/*
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*---------------------------------------------------------
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*
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* Hash_CreateEntry --
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*
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* Searches a hash table for an entry corresponding to
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* key. If no entry is found, then one is created.
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*
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* Results:
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* The return value is a pointer to the entry. If *newPtr
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* isn't NULL, then *newPtr is filled in with TRUE if a
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* new entry was created, and FALSE if an entry already existed
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* with the given key.
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*
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* Side Effects:
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* Memory may be allocated, and the hash buckets may be modified.
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*---------------------------------------------------------
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*/
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Hash_Entry *
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Hash_CreateEntry(Hash_Table *t, char *key, Boolean *newPtr)
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{
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Hash_Entry *e;
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unsigned int h;
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char *p;
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int keylen;
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struct Hash_Entry **hp;
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/*
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* Hash the key. As a side effect, save the length (strlen) of the
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* key in case we need to create the entry.
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*/
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for (h = 0, p = key; *p;)
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h = (h << 5) - h + *p++;
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keylen = p - key;
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p = key;
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for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) {
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if (e->namehash == h && strcmp(e->name, p) == 0) {
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if (newPtr != NULL)
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*newPtr = FALSE;
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return (e);
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}
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}
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/*
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* The desired entry isn't there. Before allocating a new entry,
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* expand the table if necessary (and this changes the resulting
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* bucket chain).
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*/
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if (t->numEntries >= rebuildLimit * t->size)
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RebuildTable(t);
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e = (Hash_Entry *) emalloc(sizeof(*e) + keylen);
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hp = &t->bucketPtr[h & t->mask];
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e->next = *hp;
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*hp = e;
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e->clientData = NULL;
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e->namehash = h;
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(void) strcpy(e->name, p);
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t->numEntries++;
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if (newPtr != NULL)
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*newPtr = TRUE;
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return (e);
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}
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/*
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*---------------------------------------------------------
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*
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* Hash_DeleteEntry --
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*
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* Delete the given hash table entry and free memory associated with
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* it.
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*
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* Results:
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* None.
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*
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* Side Effects:
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* Hash chain that entry lives in is modified and memory is freed.
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*
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*---------------------------------------------------------
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*/
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void
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Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e)
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{
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Hash_Entry **hp, *p;
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if (e == NULL)
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return;
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for (hp = &t->bucketPtr[e->namehash & t->mask];
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(p = *hp) != NULL; hp = &p->next) {
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if (p == e) {
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*hp = p->next;
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free((char *)p);
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t->numEntries--;
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return;
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}
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}
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(void) write(STDERR_FILENO, "bad call to Hash_DeleteEntry\n", 29);
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abort();
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}
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/*
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*---------------------------------------------------------
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*
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* Hash_EnumFirst --
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* This procedure sets things up for a complete search
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* of all entries recorded in the hash table.
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*
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* Results:
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* The return value is the address of the first entry in
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* the hash table, or NULL if the table is empty.
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*
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* Side Effects:
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* The information in searchPtr is initialized so that successive
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* calls to Hash_Next will return successive HashEntry's
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* from the table.
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*
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*---------------------------------------------------------
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*/
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Hash_Entry *
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Hash_EnumFirst(Hash_Table *t, Hash_Search *searchPtr)
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{
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searchPtr->tablePtr = t;
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searchPtr->nextIndex = 0;
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searchPtr->hashEntryPtr = NULL;
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return Hash_EnumNext(searchPtr);
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}
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/*
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*---------------------------------------------------------
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*
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* Hash_EnumNext --
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* This procedure returns successive entries in the hash table.
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*
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* Results:
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* The return value is a pointer to the next HashEntry
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* in the table, or NULL when the end of the table is
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* reached.
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*
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* Side Effects:
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* The information in searchPtr is modified to advance to the
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* next entry.
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*
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*---------------------------------------------------------
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*/
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Hash_Entry *
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Hash_EnumNext(Hash_Search *searchPtr)
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{
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Hash_Entry *e;
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Hash_Table *t = searchPtr->tablePtr;
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/*
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* The hashEntryPtr field points to the most recently returned
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* entry, or is NULL if we are starting up. If not NULL, we have
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* to start at the next one in the chain.
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*/
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e = searchPtr->hashEntryPtr;
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if (e != NULL)
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e = e->next;
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/*
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* If the chain ran out, or if we are starting up, we need to
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* find the next nonempty chain.
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*/
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while (e == NULL) {
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if (searchPtr->nextIndex >= t->size)
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return (NULL);
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e = t->bucketPtr[searchPtr->nextIndex++];
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}
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searchPtr->hashEntryPtr = e;
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return (e);
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}
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/*
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*---------------------------------------------------------
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*
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* RebuildTable --
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* This local routine makes a new hash table that
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* is larger than the old one.
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*
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* Results:
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* None.
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*
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* Side Effects:
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* The entire hash table is moved, so any bucket numbers
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* from the old table are invalid.
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*
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*---------------------------------------------------------
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*/
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static void
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RebuildTable(Hash_Table *t)
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{
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Hash_Entry *e, *next = NULL, **hp, **xp;
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int i, mask;
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Hash_Entry **oldhp;
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int oldsize;
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oldhp = t->bucketPtr;
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oldsize = i = t->size;
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i <<= 1;
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t->size = i;
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t->mask = mask = i - 1;
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t->bucketPtr = hp = (struct Hash_Entry **) emalloc(sizeof(*hp) * i);
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while (--i >= 0)
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*hp++ = NULL;
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for (hp = oldhp, i = oldsize; --i >= 0;) {
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for (e = *hp++; e != NULL; e = next) {
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next = e->next;
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xp = &t->bucketPtr[e->namehash & mask];
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e->next = *xp;
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*xp = e;
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}
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}
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free((char *)oldhp);
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}
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