nspr-4.8.6/mozilla/nsprpub/lib/ds/plhash.c - nest-learning-thermostat/5.1.7/nspr - Git at Google

 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
  * The contents of this file are subject to the Mozilla Public License Version
  * 1.1 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
  * http://www.mozilla.org/MPL/
  *
  * Software distributed under the License is distributed on an "AS IS" basis,
  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  * for the specific language governing rights and limitations under the
  * License.
  *
  * The Original Code is the Netscape Portable Runtime (NSPR).
  *
  * The Initial Developer of the Original Code is
  * Netscape Communications Corporation.
  * Portions created by the Initial Developer are Copyright (C) 1998-2000
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  * in which case the provisions of the GPL or the LGPL are applicable instead
  * of those above. If you wish to allow use of your version of this file only
  * under the terms of either the GPL or the LGPL, and not to allow others to
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */

 /*
  * PL hash table package.
  */
 #include "plhash.h"
 #include "prbit.h"
 #include "prlog.h"
 #include "prmem.h"
 #include "prtypes.h"
 #include <stdlib.h>
 #include <string.h>

 /* Compute the number of buckets in ht */
 #define NBUCKETS(ht)    (1 << (PL_HASH_BITS - (ht)->shift))

 /* The smallest table has 16 buckets */
 #define MINBUCKETSLOG2  4
 #define MINBUCKETS      (1 << MINBUCKETSLOG2)

 /* Compute the maximum entries given n buckets that we will tolerate, ~90% */
 #define OVERLOADED(n)   ((n) - ((n) >> 3))

 /* Compute the number of entries below which we shrink the table by half */
 #define UNDERLOADED(n)  (((n) > MINBUCKETS) ? ((n) >> 2) : 0)

 /*
 ** Stubs for default hash allocator ops.
 */
 static void * PR_CALLBACK
 DefaultAllocTable(void *pool, PRSize size)
 {
     return PR_MALLOC(size);
 }

 static void PR_CALLBACK
 DefaultFreeTable(void *pool, void *item)
 {
     PR_Free(item);
 }

 static PLHashEntry * PR_CALLBACK
 DefaultAllocEntry(void *pool, const void *key)
 {
     return PR_NEW(PLHashEntry);
 }

 static void PR_CALLBACK
 DefaultFreeEntry(void *pool, PLHashEntry *he, PRUintn flag)
 {
     if (flag == HT_FREE_ENTRY)
         PR_Free(he);
 }

 static PLHashAllocOps defaultHashAllocOps = {
     DefaultAllocTable, DefaultFreeTable,
     DefaultAllocEntry, DefaultFreeEntry
 };

 PR_IMPLEMENT(PLHashTable *)
 PL_NewHashTable(PRUint32 n, PLHashFunction keyHash,
                 PLHashComparator keyCompare, PLHashComparator valueCompare,
                 const PLHashAllocOps *allocOps, void *allocPriv)
 {
     PLHashTable *ht;
     PRSize nb;

     if (n <= MINBUCKETS) {
         n = MINBUCKETSLOG2;
     } else {
         n = PR_CeilingLog2(n);
         if ((PRInt32)n < 0)
             return 0;
     }

     if (!allocOps) allocOps = &defaultHashAllocOps;

     ht = (PLHashTable*)((*allocOps->allocTable)(allocPriv, sizeof *ht));
     if (!ht)
 	return 0;
     memset(ht, 0, sizeof *ht);
     ht->shift = PL_HASH_BITS - n;
     n = 1 << n;
     nb = n * sizeof(PLHashEntry *);
     ht->buckets = (PLHashEntry**)((*allocOps->allocTable)(allocPriv, nb));
     if (!ht->buckets) {
         (*allocOps->freeTable)(allocPriv, ht);
         return 0;
     }
     memset(ht->buckets, 0, nb);

     ht->keyHash = keyHash;
     ht->keyCompare = keyCompare;
     ht->valueCompare = valueCompare;
     ht->allocOps = allocOps;
     ht->allocPriv = allocPriv;
     return ht;
 }

 PR_IMPLEMENT(void)
 PL_HashTableDestroy(PLHashTable *ht)
 {
     PRUint32 i, n;
     PLHashEntry *he, *next;
     const PLHashAllocOps *allocOps = ht->allocOps;
     void *allocPriv = ht->allocPriv;

     n = NBUCKETS(ht);
     for (i = 0; i < n; i++) {
         for (he = ht->buckets[i]; he; he = next) {
             next = he->next;
             (*allocOps->freeEntry)(allocPriv, he, HT_FREE_ENTRY);
         }
     }
 #ifdef DEBUG
     memset(ht->buckets, 0xDB, n * sizeof ht->buckets[0]);
 #endif
     (*allocOps->freeTable)(allocPriv, ht->buckets);
 #ifdef DEBUG
     memset(ht, 0xDB, sizeof *ht);
 #endif
     (*allocOps->freeTable)(allocPriv, ht);
 }

 /*
 ** Multiplicative hash, from Knuth 6.4.
 */
 #define GOLDEN_RATIO    0x9E3779B9U  /* 2/(1+sqrt(5))*(2^32) */

 PR_IMPLEMENT(PLHashEntry **)
 PL_HashTableRawLookup(PLHashTable *ht, PLHashNumber keyHash, const void *key)
 {
     PLHashEntry *he, **hep, **hep0;
     PLHashNumber h;

 #ifdef HASHMETER
     ht->nlookups++;
 #endif
     h = keyHash * GOLDEN_RATIO;
     h >>= ht->shift;
     hep = hep0 = &ht->buckets[h];
     while ((he = *hep) != 0) {
         if (he->keyHash == keyHash && (*ht->keyCompare)(key, he->key)) {
             /* Move to front of chain if not already there */
             if (hep != hep0) {
                 *hep = he->next;
                 he->next = *hep0;
                 *hep0 = he;
             }
             return hep0;
         }
         hep = &he->next;
 #ifdef HASHMETER
         ht->nsteps++;
 #endif
     }
     return hep;
 }

 /*
 ** Same as PL_HashTableRawLookup but doesn't reorder the hash entries.
 */
 PR_IMPLEMENT(PLHashEntry **)
 PL_HashTableRawLookupConst(PLHashTable *ht, PLHashNumber keyHash,
                            const void *key)
 {
     PLHashEntry *he, **hep;
     PLHashNumber h;

 #ifdef HASHMETER
     ht->nlookups++;
 #endif
     h = keyHash * GOLDEN_RATIO;
     h >>= ht->shift;
     hep = &ht->buckets[h];
     while ((he = *hep) != 0) {
         if (he->keyHash == keyHash && (*ht->keyCompare)(key, he->key)) {
             break;
         }
         hep = &he->next;
 #ifdef HASHMETER
         ht->nsteps++;
 #endif
     }
     return hep;
 }

 PR_IMPLEMENT(PLHashEntry *)
 PL_HashTableRawAdd(PLHashTable *ht, PLHashEntry **hep,
                    PLHashNumber keyHash, const void *key, void *value)
 {
     PRUint32 i, n;
     PLHashEntry *he, *next, **oldbuckets;
     PRSize nb;

     /* Grow the table if it is overloaded */
     n = NBUCKETS(ht);
     if (ht->nentries >= OVERLOADED(n)) {
         oldbuckets = ht->buckets;
         nb = 2 * n * sizeof(PLHashEntry *);
         ht->buckets = (PLHashEntry**)
             ((*ht->allocOps->allocTable)(ht->allocPriv, nb));
         if (!ht->buckets) {
             ht->buckets = oldbuckets;
             return 0;
         }
         memset(ht->buckets, 0, nb);
 #ifdef HASHMETER
         ht->ngrows++;
 #endif
         ht->shift--;

         for (i = 0; i < n; i++) {
             for (he = oldbuckets[i]; he; he = next) {
                 next = he->next;
                 hep = PL_HashTableRawLookup(ht, he->keyHash, he->key);
                 PR_ASSERT(*hep == 0);
                 he->next = 0;
                 *hep = he;
             }
         }
 #ifdef DEBUG
         memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
 #endif
         (*ht->allocOps->freeTable)(ht->allocPriv, oldbuckets);
         hep = PL_HashTableRawLookup(ht, keyHash, key);
     }

     /* Make a new key value entry */
     he = (*ht->allocOps->allocEntry)(ht->allocPriv, key);
     if (!he)
 	return 0;
     he->keyHash = keyHash;
     he->key = key;
     he->value = value;
     he->next = *hep;
     *hep = he;
     ht->nentries++;
     return he;
 }

 PR_IMPLEMENT(PLHashEntry *)
 PL_HashTableAdd(PLHashTable *ht, const void *key, void *value)
 {
     PLHashNumber keyHash;
     PLHashEntry *he, **hep;

     keyHash = (*ht->keyHash)(key);
     hep = PL_HashTableRawLookup(ht, keyHash, key);
     if ((he = *hep) != 0) {
         /* Hit; see if values match */
         if ((*ht->valueCompare)(he->value, value)) {
             /* key,value pair is already present in table */
             return he;
         }
         if (he->value)
             (*ht->allocOps->freeEntry)(ht->allocPriv, he, HT_FREE_VALUE);
         he->value = value;
         return he;
     }
     return PL_HashTableRawAdd(ht, hep, keyHash, key, value);
 }

 PR_IMPLEMENT(void)
 PL_HashTableRawRemove(PLHashTable *ht, PLHashEntry **hep, PLHashEntry *he)
 {
     PRUint32 i, n;
     PLHashEntry *next, **oldbuckets;
     PRSize nb;

     *hep = he->next;
     (*ht->allocOps->freeEntry)(ht->allocPriv, he, HT_FREE_ENTRY);

     /* Shrink table if it's underloaded */
     n = NBUCKETS(ht);
     if (--ht->nentries < UNDERLOADED(n)) {
         oldbuckets = ht->buckets;
         nb = n * sizeof(PLHashEntry*) / 2;
         ht->buckets = (PLHashEntry**)(
             (*ht->allocOps->allocTable)(ht->allocPriv, nb));
         if (!ht->buckets) {
             ht->buckets = oldbuckets;
             return;
         }
         memset(ht->buckets, 0, nb);
 #ifdef HASHMETER
         ht->nshrinks++;
 #endif
         ht->shift++;

         for (i = 0; i < n; i++) {
             for (he = oldbuckets[i]; he; he = next) {
                 next = he->next;
                 hep = PL_HashTableRawLookup(ht, he->keyHash, he->key);
                 PR_ASSERT(*hep == 0);
                 he->next = 0;
                 *hep = he;
             }
         }
 #ifdef DEBUG
         memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
 #endif
         (*ht->allocOps->freeTable)(ht->allocPriv, oldbuckets);
     }
 }

 PR_IMPLEMENT(PRBool)
 PL_HashTableRemove(PLHashTable *ht, const void *key)
 {
     PLHashNumber keyHash;
     PLHashEntry *he, **hep;

     keyHash = (*ht->keyHash)(key);
     hep = PL_HashTableRawLookup(ht, keyHash, key);
     if ((he = *hep) == 0)
         return PR_FALSE;

     /* Hit; remove element */
     PL_HashTableRawRemove(ht, hep, he);
     return PR_TRUE;
 }

 PR_IMPLEMENT(void *)
 PL_HashTableLookup(PLHashTable *ht, const void *key)
 {
     PLHashNumber keyHash;
     PLHashEntry *he, **hep;

     keyHash = (*ht->keyHash)(key);
     hep = PL_HashTableRawLookup(ht, keyHash, key);
     if ((he = *hep) != 0) {
         return he->value;
     }
     return 0;
 }

 /*
 ** Same as PL_HashTableLookup but doesn't reorder the hash entries.
 */
 PR_IMPLEMENT(void *)
 PL_HashTableLookupConst(PLHashTable *ht, const void *key)
 {
     PLHashNumber keyHash;
     PLHashEntry *he, **hep;

     keyHash = (*ht->keyHash)(key);
     hep = PL_HashTableRawLookupConst(ht, keyHash, key);
     if ((he = *hep) != 0) {
         return he->value;
     }
     return 0;
 }

 /*
 ** Iterate over the entries in the hash table calling func for each
 ** entry found. Stop if "f" says to (return value & PR_ENUMERATE_STOP).
 ** Return a count of the number of elements scanned.
 */
 PR_IMPLEMENT(int)
 PL_HashTableEnumerateEntries(PLHashTable *ht, PLHashEnumerator f, void *arg)
 {
     PLHashEntry *he, **hep;
     PRUint32 i, nbuckets;
     int rv, n = 0;
     PLHashEntry *todo = 0;

     nbuckets = NBUCKETS(ht);
     for (i = 0; i < nbuckets; i++) {
         hep = &ht->buckets[i];
         while ((he = *hep) != 0) {
             rv = (*f)(he, n, arg);
             n++;
             if (rv & (HT_ENUMERATE_REMOVE | HT_ENUMERATE_UNHASH)) {
                 *hep = he->next;
                 if (rv & HT_ENUMERATE_REMOVE) {
                     he->next = todo;
                     todo = he;
                 }
             } else {
                 hep = &he->next;
             }
             if (rv & HT_ENUMERATE_STOP) {
                 goto out;
             }
         }
     }

 out:
     hep = &todo;
     while ((he = *hep) != 0) {
         PL_HashTableRawRemove(ht, hep, he);
     }
     return n;
 }

 #ifdef HASHMETER
 #include <math.h>
 #include <stdio.h>

 PR_IMPLEMENT(void)
 PL_HashTableDumpMeter(PLHashTable *ht, PLHashEnumerator dump, FILE *fp)
 {
     double mean, variance;
     PRUint32 nchains, nbuckets;
     PRUint32 i, n, maxChain, maxChainLen;
     PLHashEntry *he;

     variance = 0;
     nchains = 0;
     maxChainLen = 0;
     nbuckets = NBUCKETS(ht);
     for (i = 0; i < nbuckets; i++) {
         he = ht->buckets[i];
         if (!he)
             continue;
         nchains++;
         for (n = 0; he; he = he->next)
             n++;
         variance += n * n;
         if (n > maxChainLen) {
             maxChainLen = n;
             maxChain = i;
         }
     }
     mean = (double)ht->nentries / nchains;
     variance = fabs(variance / nchains - mean * mean);

     fprintf(fp, "\nHash table statistics:\n");
     fprintf(fp, "     number of lookups: %u\n", ht->nlookups);
     fprintf(fp, "     number of entries: %u\n", ht->nentries);
     fprintf(fp, "       number of grows: %u\n", ht->ngrows);
     fprintf(fp, "     number of shrinks: %u\n", ht->nshrinks);
     fprintf(fp, "   mean steps per hash: %g\n", (double)ht->nsteps
                                                 / ht->nlookups);
     fprintf(fp, "mean hash chain length: %g\n", mean);
     fprintf(fp, "    standard deviation: %g\n", sqrt(variance));
     fprintf(fp, " max hash chain length: %u\n", maxChainLen);
     fprintf(fp, "        max hash chain: [%u]\n", maxChain);

     for (he = ht->buckets[maxChain], i = 0; he; he = he->next, i++)
         if ((*dump)(he, i, fp) != HT_ENUMERATE_NEXT)
             break;
 }
 #endif /* HASHMETER */

 PR_IMPLEMENT(int)
 PL_HashTableDump(PLHashTable *ht, PLHashEnumerator dump, FILE *fp)
 {
     int count;

     count = PL_HashTableEnumerateEntries(ht, dump, fp);
 #ifdef HASHMETER
     PL_HashTableDumpMeter(ht, dump, fp);
 #endif
     return count;
 }

 PR_IMPLEMENT(PLHashNumber)
 PL_HashString(const void *key)
 {
     PLHashNumber h;
     const PRUint8 *s;

     h = 0;
     for (s = (const PRUint8*)key; *s; s++)
         h = PR_ROTATE_LEFT32(h, 4) ^ *s;
     return h;
 }

 PR_IMPLEMENT(int)
 PL_CompareStrings(const void *v1, const void *v2)
 {
     return strcmp((const char*)v1, (const char*)v2) == 0;
 }

 PR_IMPLEMENT(int)
 PL_CompareValues(const void *v1, const void *v2)
 {
     return v1 == v2;
 }
	/* -- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -- */
	/* *** BEGIN LICENSE BLOCK ***
	* Version: MPL 1.1/GPL 2.0/LGPL 2.1
	*
	* The contents of this file are subject to the Mozilla Public License Version
	* 1.1 (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	* http://www.mozilla.org/MPL/
	*
	* Software distributed under the License is distributed on an "AS IS" basis,
	* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
	* for the specific language governing rights and limitations under the
	* License.
	*
	* The Original Code is the Netscape Portable Runtime (NSPR).
	*
	* The Initial Developer of the Original Code is
	* Netscape Communications Corporation.
	* Portions created by the Initial Developer are Copyright (C) 1998-2000
	* the Initial Developer. All Rights Reserved.
	*
	* Contributor(s):
	*
	* Alternatively, the contents of this file may be used under the terms of
	* either the GNU General Public License Version 2 or later (the "GPL"), or
	* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
	* in which case the provisions of the GPL or the LGPL are applicable instead
	* of those above. If you wish to allow use of your version of this file only
	* under the terms of either the GPL or the LGPL, and not to allow others to
	* use your version of this file under the terms of the MPL, indicate your
	* decision by deleting the provisions above and replace them with the notice
	* and other provisions required by the GPL or the LGPL. If you do not delete
	* the provisions above, a recipient may use your version of this file under
	* the terms of any one of the MPL, the GPL or the LGPL.
	*
	* *** END LICENSE BLOCK *** */

	/*
	* PL hash table package.
	*/
	#include "plhash.h"
	#include "prbit.h"
	#include "prlog.h"
	#include "prmem.h"
	#include "prtypes.h"
	#include <stdlib.h>
	#include <string.h>

	/* Compute the number of buckets in ht */
	#define NBUCKETS(ht) (1 << (PL_HASH_BITS - (ht)->shift))

	/* The smallest table has 16 buckets */
	#define MINBUCKETSLOG2 4
	#define MINBUCKETS (1 << MINBUCKETSLOG2)

	/* Compute the maximum entries given n buckets that we will tolerate, ~90% */
	#define OVERLOADED(n) ((n) - ((n) >> 3))

	/* Compute the number of entries below which we shrink the table by half */
	#define UNDERLOADED(n) (((n) > MINBUCKETS) ? ((n) >> 2) : 0)

	/*
	** Stubs for default hash allocator ops.
	*/
	static void * PR_CALLBACK
	DefaultAllocTable(void *pool, PRSize size)
	{
	return PR_MALLOC(size);
	}

	static void PR_CALLBACK
	DefaultFreeTable(void pool, void item)
	{
	PR_Free(item);
	}

	static PLHashEntry * PR_CALLBACK
	DefaultAllocEntry(void pool, const void key)
	{
	return PR_NEW(PLHashEntry);
	}

	static void PR_CALLBACK
	DefaultFreeEntry(void pool, PLHashEntry he, PRUintn flag)
	{
	if (flag == HT_FREE_ENTRY)
	PR_Free(he);
	}

	static PLHashAllocOps defaultHashAllocOps = {
	DefaultAllocTable, DefaultFreeTable,
	DefaultAllocEntry, DefaultFreeEntry
	};

	PR_IMPLEMENT(PLHashTable *)
	PL_NewHashTable(PRUint32 n, PLHashFunction keyHash,
	PLHashComparator keyCompare, PLHashComparator valueCompare,
	const PLHashAllocOps allocOps, void allocPriv)
	{
	PLHashTable *ht;
	PRSize nb;

	if (n <= MINBUCKETS) {
	n = MINBUCKETSLOG2;
	} else {
	n = PR_CeilingLog2(n);
	if ((PRInt32)n < 0)
	return 0;
	}

	if (!allocOps) allocOps = &defaultHashAllocOps;

	ht = (PLHashTable)((allocOps->allocTable)(allocPriv, sizeof *ht));
	if (!ht)
	return 0;
	memset(ht, 0, sizeof *ht);
	ht->shift = PL_HASH_BITS - n;
	n = 1 << n;
	nb = n * sizeof(PLHashEntry *);
	ht->buckets = (PLHashEntry*)((allocOps->allocTable)(allocPriv, nb));
	if (!ht->buckets) {
	(*allocOps->freeTable)(allocPriv, ht);
	return 0;
	}
	memset(ht->buckets, 0, nb);

	ht->keyHash = keyHash;
	ht->keyCompare = keyCompare;
	ht->valueCompare = valueCompare;
	ht->allocOps = allocOps;
	ht->allocPriv = allocPriv;
	return ht;
	}

	PR_IMPLEMENT(void)
	PL_HashTableDestroy(PLHashTable *ht)
	{
	PRUint32 i, n;
	PLHashEntry he, next;
	const PLHashAllocOps *allocOps = ht->allocOps;
	void *allocPriv = ht->allocPriv;

	n = NBUCKETS(ht);
	for (i = 0; i < n; i++) {
	for (he = ht->buckets[i]; he; he = next) {
	next = he->next;
	(*allocOps->freeEntry)(allocPriv, he, HT_FREE_ENTRY);
	}
	}
	#ifdef DEBUG
	memset(ht->buckets, 0xDB, n * sizeof ht->buckets[0]);
	#endif
	(*allocOps->freeTable)(allocPriv, ht->buckets);
	#ifdef DEBUG
	memset(ht, 0xDB, sizeof *ht);
	#endif
	(*allocOps->freeTable)(allocPriv, ht);
	}

	/*
	** Multiplicative hash, from Knuth 6.4.
	*/
	#define GOLDEN_RATIO 0x9E3779B9U /* 2/(1+sqrt(5))(2^32) /

	PR_IMPLEMENT(PLHashEntry **)
	PL_HashTableRawLookup(PLHashTable ht, PLHashNumber keyHash, const void key)
	{
	PLHashEntry he, hep, *hep0;
	PLHashNumber h;

	#ifdef HASHMETER
	ht->nlookups++;
	#endif
	h = keyHash * GOLDEN_RATIO;
	h >>= ht->shift;
	hep = hep0 = &ht->buckets[h];
	while ((he = *hep) != 0) {
	if (he->keyHash == keyHash && (*ht->keyCompare)(key, he->key)) {
	/* Move to front of chain if not already there */
	if (hep != hep0) {
	*hep = he->next;
	he->next = *hep0;
	*hep0 = he;
	}
	return hep0;
	}
	hep = &he->next;
	#ifdef HASHMETER
	ht->nsteps++;
	#endif
	}
	return hep;
	}

	/*
	** Same as PL_HashTableRawLookup but doesn't reorder the hash entries.
	*/
	PR_IMPLEMENT(PLHashEntry **)
	PL_HashTableRawLookupConst(PLHashTable *ht, PLHashNumber keyHash,
	const void *key)
	{
	PLHashEntry he, *hep;
	PLHashNumber h;

	#ifdef HASHMETER
	ht->nlookups++;
	#endif
	h = keyHash * GOLDEN_RATIO;
	h >>= ht->shift;
	hep = &ht->buckets[h];
	while ((he = *hep) != 0) {
	if (he->keyHash == keyHash && (*ht->keyCompare)(key, he->key)) {
	break;
	}
	hep = &he->next;
	#ifdef HASHMETER
	ht->nsteps++;
	#endif
	}
	return hep;
	}

	PR_IMPLEMENT(PLHashEntry *)
	PL_HashTableRawAdd(PLHashTable ht, PLHashEntry *hep,
	PLHashNumber keyHash, const void key, void value)
	{
	PRUint32 i, n;
	PLHashEntry he, next, **oldbuckets;
	PRSize nb;

	/* Grow the table if it is overloaded */
	n = NBUCKETS(ht);
	if (ht->nentries >= OVERLOADED(n)) {
	oldbuckets = ht->buckets;
	nb = 2 * n * sizeof(PLHashEntry *);
	ht->buckets = (PLHashEntry**)
	((*ht->allocOps->allocTable)(ht->allocPriv, nb));
	if (!ht->buckets) {
	ht->buckets = oldbuckets;
	return 0;
	}
	memset(ht->buckets, 0, nb);
	#ifdef HASHMETER
	ht->ngrows++;
	#endif
	ht->shift--;

	for (i = 0; i < n; i++) {
	for (he = oldbuckets[i]; he; he = next) {
	next = he->next;
	hep = PL_HashTableRawLookup(ht, he->keyHash, he->key);
	PR_ASSERT(*hep == 0);
	he->next = 0;
	*hep = he;
	}
	}
	#ifdef DEBUG
	memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
	#endif
	(*ht->allocOps->freeTable)(ht->allocPriv, oldbuckets);
	hep = PL_HashTableRawLookup(ht, keyHash, key);
	}

	/* Make a new key value entry */
	he = (*ht->allocOps->allocEntry)(ht->allocPriv, key);
	if (!he)
	return 0;
	he->keyHash = keyHash;
	he->key = key;
	he->value = value;
	he->next = *hep;
	*hep = he;
	ht->nentries++;
	return he;
	}

	PR_IMPLEMENT(PLHashEntry *)
	PL_HashTableAdd(PLHashTable ht, const void key, void *value)
	{
	PLHashNumber keyHash;
	PLHashEntry he, *hep;

	keyHash = (*ht->keyHash)(key);
	hep = PL_HashTableRawLookup(ht, keyHash, key);
	if ((he = *hep) != 0) {
	/* Hit; see if values match */
	if ((*ht->valueCompare)(he->value, value)) {
	/* key,value pair is already present in table */
	return he;
	}
	if (he->value)
	(*ht->allocOps->freeEntry)(ht->allocPriv, he, HT_FREE_VALUE);
	he->value = value;
	return he;
	}
	return PL_HashTableRawAdd(ht, hep, keyHash, key, value);
	}

	PR_IMPLEMENT(void)
	PL_HashTableRawRemove(PLHashTable ht, PLHashEntry hep, PLHashEntry he)
	{
	PRUint32 i, n;
	PLHashEntry next, *oldbuckets;
	PRSize nb;

	*hep = he->next;
	(*ht->allocOps->freeEntry)(ht->allocPriv, he, HT_FREE_ENTRY);

	/* Shrink table if it's underloaded */
	n = NBUCKETS(ht);
	if (--ht->nentries < UNDERLOADED(n)) {
	oldbuckets = ht->buckets;
	nb = n * sizeof(PLHashEntry*) / 2;
	ht->buckets = (PLHashEntry**)(
	(*ht->allocOps->allocTable)(ht->allocPriv, nb));
	if (!ht->buckets) {
	ht->buckets = oldbuckets;
	return;
	}
	memset(ht->buckets, 0, nb);
	#ifdef HASHMETER
	ht->nshrinks++;
	#endif
	ht->shift++;

	for (i = 0; i < n; i++) {
	for (he = oldbuckets[i]; he; he = next) {
	next = he->next;
	hep = PL_HashTableRawLookup(ht, he->keyHash, he->key);
	PR_ASSERT(*hep == 0);
	he->next = 0;
	*hep = he;
	}
	}
	#ifdef DEBUG
	memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
	#endif
	(*ht->allocOps->freeTable)(ht->allocPriv, oldbuckets);
	}
	}

	PR_IMPLEMENT(PRBool)
	PL_HashTableRemove(PLHashTable ht, const void key)
	{
	PLHashNumber keyHash;
	PLHashEntry he, *hep;

	keyHash = (*ht->keyHash)(key);
	hep = PL_HashTableRawLookup(ht, keyHash, key);
	if ((he = *hep) == 0)
	return PR_FALSE;

	/* Hit; remove element */
	PL_HashTableRawRemove(ht, hep, he);
	return PR_TRUE;
	}

	PR_IMPLEMENT(void *)
	PL_HashTableLookup(PLHashTable ht, const void key)
	{
	PLHashNumber keyHash;
	PLHashEntry he, *hep;

	keyHash = (*ht->keyHash)(key);
	hep = PL_HashTableRawLookup(ht, keyHash, key);
	if ((he = *hep) != 0) {
	return he->value;
	}
	return 0;
	}

	/*
	** Same as PL_HashTableLookup but doesn't reorder the hash entries.
	*/
	PR_IMPLEMENT(void *)
	PL_HashTableLookupConst(PLHashTable ht, const void key)
	{
	PLHashNumber keyHash;
	PLHashEntry he, *hep;

	keyHash = (*ht->keyHash)(key);
	hep = PL_HashTableRawLookupConst(ht, keyHash, key);
	if ((he = *hep) != 0) {
	return he->value;
	}
	return 0;
	}

	/*
	** Iterate over the entries in the hash table calling func for each
	** entry found. Stop if "f" says to (return value & PR_ENUMERATE_STOP).
	** Return a count of the number of elements scanned.
	*/
	PR_IMPLEMENT(int)
	PL_HashTableEnumerateEntries(PLHashTable ht, PLHashEnumerator f, void arg)
	{
	PLHashEntry he, *hep;
	PRUint32 i, nbuckets;
	int rv, n = 0;
	PLHashEntry *todo = 0;

	nbuckets = NBUCKETS(ht);
	for (i = 0; i < nbuckets; i++) {
	hep = &ht->buckets[i];
	while ((he = *hep) != 0) {
	rv = (*f)(he, n, arg);
	n++;
	if (rv & (HT_ENUMERATE_REMOVE \| HT_ENUMERATE_UNHASH)) {
	*hep = he->next;
	if (rv & HT_ENUMERATE_REMOVE) {
	he->next = todo;
	todo = he;
	}
	} else {
	hep = &he->next;
	}
	if (rv & HT_ENUMERATE_STOP) {
	goto out;
	}
	}
	}

	out:
	hep = &todo;
	while ((he = *hep) != 0) {
	PL_HashTableRawRemove(ht, hep, he);
	}
	return n;
	}

	#ifdef HASHMETER
	#include <math.h>
	#include <stdio.h>

	PR_IMPLEMENT(void)
	PL_HashTableDumpMeter(PLHashTable ht, PLHashEnumerator dump, FILE fp)
	{
	double mean, variance;
	PRUint32 nchains, nbuckets;
	PRUint32 i, n, maxChain, maxChainLen;
	PLHashEntry *he;

	variance = 0;
	nchains = 0;
	maxChainLen = 0;
	nbuckets = NBUCKETS(ht);
	for (i = 0; i < nbuckets; i++) {
	he = ht->buckets[i];
	if (!he)
	continue;
	nchains++;
	for (n = 0; he; he = he->next)
	n++;
	variance += n * n;
	if (n > maxChainLen) {
	maxChainLen = n;
	maxChain = i;
	}
	}
	mean = (double)ht->nentries / nchains;
	variance = fabs(variance / nchains - mean * mean);

	fprintf(fp, "\nHash table statistics:\n");
	fprintf(fp, " number of lookups: %u\n", ht->nlookups);
	fprintf(fp, " number of entries: %u\n", ht->nentries);
	fprintf(fp, " number of grows: %u\n", ht->ngrows);
	fprintf(fp, " number of shrinks: %u\n", ht->nshrinks);
	fprintf(fp, " mean steps per hash: %g\n", (double)ht->nsteps
	/ ht->nlookups);
	fprintf(fp, "mean hash chain length: %g\n", mean);
	fprintf(fp, " standard deviation: %g\n", sqrt(variance));
	fprintf(fp, " max hash chain length: %u\n", maxChainLen);
	fprintf(fp, " max hash chain: [%u]\n", maxChain);

	for (he = ht->buckets[maxChain], i = 0; he; he = he->next, i++)
	if ((*dump)(he, i, fp) != HT_ENUMERATE_NEXT)
	break;
	}
	#endif /* HASHMETER */

	PR_IMPLEMENT(int)
	PL_HashTableDump(PLHashTable ht, PLHashEnumerator dump, FILE fp)
	{
	int count;

	count = PL_HashTableEnumerateEntries(ht, dump, fp);
	#ifdef HASHMETER
	PL_HashTableDumpMeter(ht, dump, fp);
	#endif
	return count;
	}

	PR_IMPLEMENT(PLHashNumber)
	PL_HashString(const void *key)
	{
	PLHashNumber h;
	const PRUint8 *s;

	h = 0;
	for (s = (const PRUint8)key; s; s++)
	h = PR_ROTATE_LEFT32(h, 4) ^ *s;
	return h;
	}

	PR_IMPLEMENT(int)
	PL_CompareStrings(const void v1, const void v2)
	{
	return strcmp((const char)v1, (const char)v2) == 0;
	}

	PR_IMPLEMENT(int)
	PL_CompareValues(const void v1, const void v2)
	{
	return v1 == v2;
	}