cpu/ixp/npe/IxEthDBHashtable.c - uboot/prism - Git at Google

 /**
  * @file ethHash.c
  *
  * @brief Hashtable implementation
  *
  * @par
  * IXP400 SW Release version 2.0
  *
  * -- Copyright Notice --
  *
  * @par
  * Copyright 2001-2005, Intel Corporation.
  * All rights reserved.
  *
  * @par
  * 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 Intel Corporation nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * @par
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
  *
  * @par
  * -- End of Copyright Notice --
  */


 #include "IxEthDB_p.h"
 #include "IxEthDBLocks_p.h"

 /**
  * @addtogroup EthDB
  *
  * @{
  */

 /**
  * @brief initializes a hash table object
  *
  * @param hashTable uninitialized hash table structure
  * @param numBuckets number of buckets to use
  * @param entryHashFunction hash function used
  * to hash entire hash node data block (for adding)
  * @param matchFunctions array of match functions, indexed on type,
  * used to differentiate records with the same hash value
  * @param freeFunction function used to free node data blocks
  *
  * Initializes the given hash table object.
  *
  * @internal
  */
 void ixEthDBInitHash(HashTable *hashTable,
                      UINT32 numBuckets,
                      HashFunction entryHashFunction,
                      MatchFunction *matchFunctions,
                      FreeFunction freeFunction)
 {
     UINT32 bucketIndex;
     UINT32 hashSize = numBuckets * sizeof(HashNode *);

     /* entry hashing, matching and freeing methods */
     hashTable->entryHashFunction  = entryHashFunction;
     hashTable->matchFunctions     = matchFunctions;
     hashTable->freeFunction       = freeFunction;

     /* buckets */
     hashTable->numBuckets = numBuckets;

     /* set to 0 all buckets */
     memset(hashTable->hashBuckets, 0, hashSize);

     /* init bucket locks - note that initially all mutexes are unlocked after MutexInit()*/
     for (bucketIndex = 0 ; bucketIndex < numBuckets ; bucketIndex++)
     {
         ixOsalFastMutexInit(&hashTable->bucketLocks[bucketIndex]);
     }
 }

 /**
  * @brief adds an entry to the hash table
  *
  * @param hashTable hash table to add the entry to
  * @param entry entry to add
  *
  * The entry will be hashed using the entry hashing function and added to the
  * hash table, unless a locking blockage occurs, in which case the caller
  * should retry.
  *
  * @retval IX_ETH_DB_SUCCESS if adding <i>entry</i> has succeeded
  * @retval IX_ETH_DB_NOMEM if there's no memory left in the hash node pool
  * @retval IX_ETH_DB_BUSY if there's a locking failure on the insertion path
  *
  * @internal
  */
 IX_ETH_DB_PUBLIC IxEthDBStatus ixEthDBAddHashEntry(HashTable *hashTable, void *entry)
 {
     UINT32 hashValue   = hashTable->entryHashFunction(entry);
     UINT32 bucketIndex = hashValue % hashTable->numBuckets;
     HashNode *bucket   = hashTable->hashBuckets[bucketIndex];
     HashNode *newNode;

     LockStack locks;

     INIT_STACK(&locks);

     /* lock bucket */
     PUSH_LOCK(&locks, &hashTable->bucketLocks[bucketIndex]);

     /* lock insertion element (first in chain), if any */
     if (bucket != NULL)
     {
         PUSH_LOCK(&locks, &bucket->lock);
     }

     /* get new node */
     newNode = ixEthDBAllocHashNode();

     if (newNode == NULL)
     {
         /* unlock everything */
         UNROLL_STACK(&locks);

         return IX_ETH_DB_NOMEM;
     }

     /* init lock - note that mutexes are unlocked after MutexInit */
     ixOsalFastMutexInit(&newNode->lock);

     /* populate new link */
     newNode->data = entry;

     /* add to bucket */
     newNode->next                       = bucket;
     hashTable->hashBuckets[bucketIndex] = newNode;

     /* unlock bucket and insertion point */
     UNROLL_STACK(&locks);

     return IX_ETH_DB_SUCCESS;
 }

 /**
  * @brief removes an entry from the hashtable
  *
  * @param hashTable hash table to remove entry from
  * @param keyType type of record key used for matching
  * @param reference reference key used to identify the entry
  *
  * The reference key will be hashed using the key hashing function,
  * the entry is searched using the hashed value and then examined
  * against the reference entry using the match function. A positive
  * match will trigger the deletion of the entry.
  * Locking failures are reported and the caller should retry.
  *
  * @retval IX_ETH_DB_SUCCESS if the removal was successful
  * @retval IX_ETH_DB_NO_SUCH_ADDR if the entry was not found
  * @retval IX_ETH_DB_BUSY if a locking failure occured during the process
  *
  * @internal
  */
 IxEthDBStatus ixEthDBRemoveHashEntry(HashTable *hashTable, int keyType, void *reference)
 {
     UINT32 hashValue       = hashTable->entryHashFunction(reference);
     UINT32 bucketIndex     = hashValue % hashTable->numBuckets;
     HashNode *node         = hashTable->hashBuckets[bucketIndex];
     HashNode *previousNode = NULL;

     LockStack locks;

     INIT_STACK(&locks);

     while (node != NULL)
     {
         /* try to lock node */
         PUSH_LOCK(&locks, &node->lock);

         if (hashTable->matchFunctions[keyType](reference, node->data))
         {
             /* found entry */
             if (node->next != NULL)
             {
                 PUSH_LOCK(&locks, &node->next->lock);
             }

             if (previousNode == NULL)
             {
                 /* node is head of chain */
                 PUSH_LOCK(&locks, &hashTable->bucketLocks[bucketIndex]);

                 hashTable->hashBuckets[bucketIndex] = node->next;

                 POP_LOCK(&locks);
             }
             else
             {
                 /* relink */
                 previousNode->next = node->next;
             }

             UNROLL_STACK(&locks);

             /* free node */
             hashTable->freeFunction(node->data);
             ixEthDBFreeHashNode(node);

             return IX_ETH_DB_SUCCESS;
         }
         else
         {
             if (previousNode != NULL)
             {
                 /* unlock previous node */
                 SHIFT_STACK(&locks);
             }

             /* advance to next element in chain */
             previousNode = node;
             node         = node->next;
         }
     }

     UNROLL_STACK(&locks);

     /* not found */
     return IX_ETH_DB_NO_SUCH_ADDR;
 }

 /**
  * @brief retrieves an entry from the hash table
  *
  * @param hashTable hash table to perform the search into
  * @param reference search key (a MAC address)
  * @param keyType type of record key used for matching
  * @param searchResult pointer where a reference to the located hash node
  * is placed
  *
  * Searches the entry with the same key as <i>reference</i> and places the
  * pointer to the resulting node in <i>searchResult</i>.
  * An implicit write access lock is granted after a search, which gives the
  * caller the opportunity to modify the entry.
  * Access should be released as soon as possible using @ref ixEthDBReleaseHashNode().
  *
  * @see ixEthDBReleaseHashNode()
  *
  * @retval IX_ETH_DB_SUCCESS if the search was completed successfully
  * @retval IX_ETH_DB_NO_SUCH_ADDRESS if no entry with the given key was found
  * @retval IX_ETH_DB_BUSY if a locking failure has occured, in which case
  * the caller should retry
  *
  * @warning unless the return value is <b>IX_ETH_DB_SUCCESS</b> the searchResult
  * location is NOT modified and therefore using a NULL comparison test when the
  * value was not properly initialized would be an error
  *
  * @internal
  */
 IxEthDBStatus ixEthDBSearchHashEntry(HashTable *hashTable, int keyType, void *reference, HashNode **searchResult)
 {
     UINT32 hashValue;
     HashNode *node;

     hashValue = hashTable->entryHashFunction(reference);
     node      = hashTable->hashBuckets[hashValue % hashTable->numBuckets];

     while (node != NULL)
     {
         TRY_LOCK(&node->lock);

         if (hashTable->matchFunctions[keyType](reference, node->data))
         {
             *searchResult = node;

             return IX_ETH_DB_SUCCESS;
         }
         else
         {
             UNLOCK(&node->lock);

             node = node->next;
         }
     }

     /* not found */
     return IX_ETH_DB_NO_SUCH_ADDR;
 }

 /**
  * @brief reports the existence of an entry in the hash table
  *
  * @param hashTable hash table to perform the search into
  * @param reference search key (a MAC address)
  * @param keyType type of record key used for matching
  *
  * Searches the entry with the same key as <i>reference</i>.
  * No implicit write access lock is granted after a search, hence the
  * caller cannot access or modify the entry. The result is only temporary.
  *
  * @see ixEthDBReleaseHashNode()
  *
  * @retval IX_ETH_DB_SUCCESS if the search was completed successfully
  * @retval IX_ETH_DB_NO_SUCH_ADDRESS if no entry with the given key was found
  * @retval IX_ETH_DB_BUSY if a locking failure has occured, in which case
  * the caller should retry
  *
  * @internal
  */
 IxEthDBStatus ixEthDBPeekHashEntry(HashTable *hashTable, int keyType, void *reference)
 {
     UINT32 hashValue;
     HashNode *node;

     hashValue = hashTable->entryHashFunction(reference);
     node      = hashTable->hashBuckets[hashValue % hashTable->numBuckets];

     while (node != NULL)
     {
         TRY_LOCK(&node->lock);

         if (hashTable->matchFunctions[keyType](reference, node->data))
         {
             UNLOCK(&node->lock);

             return IX_ETH_DB_SUCCESS;
         }
         else
         {
             UNLOCK(&node->lock);

             node = node->next;
         }
     }

     /* not found */
     return IX_ETH_DB_NO_SUCH_ADDR;
 }

 /**
  * @brief releases the write access lock
  *
  * @pre the node should have been obtained via @ref ixEthDBSearchHashEntry()
  *
  * @see ixEthDBSearchHashEntry()
  *
  * @internal
  */
 void ixEthDBReleaseHashNode(HashNode *node)
 {
     UNLOCK(&node->lock);
 }

 /**
  * @brief initializes a hash iterator
  *
  * @param hashTable hash table to be iterated
  * @param iterator iterator object
  *
  * If the initialization is successful the iterator will point to the
  * first hash table record (if any).
  * Testing if the iterator has not passed the end of the table should be
  * done using the IS_ITERATOR_VALID(iteratorPtr) macro.
  * An implicit write access lock is granted on the entry pointed by the iterator.
  * The access is automatically revoked when the iterator is incremented.
  * If the caller decides to terminate the iteration before the end of the table is
  * passed then the manual access release method, @ref ixEthDBReleaseHashIterator,
  * must be called.
  *
  * @see ixEthDBReleaseHashIterator()
  *
  * @retval IX_ETH_DB_SUCCESS if initialization was successful and the iterator points
  * to the first valid table node
  * @retval IX_ETH_DB_FAIL if the table is empty
  * @retval IX_ETH_DB_BUSY if a locking failure has occured, in which case the caller
  * should retry
  *
  * @warning do not use ixEthDBReleaseHashNode() on entries pointed by the iterator, as this
  * might place the database in a permanent invalid lock state
  *
  * @internal
  */
 IxEthDBStatus ixEthDBInitHashIterator(HashTable *hashTable, HashIterator *iterator)
 {
     iterator->bucketIndex  = 0;
     iterator->node         = NULL;
     iterator->previousNode = NULL;

     return ixEthDBIncrementHashIterator(hashTable, iterator);
 }

 /**
  * @brief releases the write access locks of the iterator nodes
  *
  * @warning use of this function is required only when the caller terminates an iteration
  * before reaching the end of the table
  *
  * @see ixEthDBInitHashIterator()
  * @see ixEthDBIncrementHashIterator()
  *
  * @param iterator iterator whose node(s) should be unlocked
  *
  * @internal
  */
 void ixEthDBReleaseHashIterator(HashIterator *iterator)
 {
     if (iterator->previousNode != NULL)
     {
         UNLOCK(&iterator->previousNode->lock);
     }

     if (iterator->node != NULL)
     {
         UNLOCK(&iterator->node->lock);
     }
 }

 /**
  * @brief incremenents an iterator so that it points to the next valid entry of the table
  * (if any)
  *
  * @param hashTable hash table to iterate
  * @param iterator iterator object
  *
  * @pre the iterator object must be initialized using @ref ixEthDBInitHashIterator()
  *
  * If the increment operation is successful the iterator will point to the
  * next hash table record (if any).
  * Testing if the iterator has not passed the end of the table should be
  * done using the IS_ITERATOR_VALID(iteratorPtr) macro.
  * An implicit write access lock is granted on the entry pointed by the iterator.
  * The access is automatically revoked when the iterator is re-incremented.
  * If the caller decides to terminate the iteration before the end of the table is
  * passed then the manual access release method, @ref ixEthDBReleaseHashIterator,
  * must be called.
  * Is is guaranteed that no other thread can remove or change the iterated entry until
  * the iterator is incremented successfully.
  *
  * @see ixEthDBReleaseHashIterator()
  *
  * @retval IX_ETH_DB_SUCCESS if the operation was successful and the iterator points
  * to the next valid table node
  * @retval IX_ETH_DB_FAIL if the iterator has passed the end of the table
  * @retval IX_ETH_DB_BUSY if a locking failure has occured, in which case the caller
  * should retry
  *
  * @warning do not use ixEthDBReleaseHashNode() on entries pointed by the iterator, as this
  * might place the database in a permanent invalid lock state
  *
  * @internal
  */
 IxEthDBStatus ixEthDBIncrementHashIterator(HashTable *hashTable, HashIterator *iterator)
 {
     /* unless iterator is just initialized... */
     if (iterator->node != NULL)
     {
         /* try next in chain */
         if (iterator->node->next != NULL)
         {
             TRY_LOCK(&iterator->node->next->lock);

             if (iterator->previousNode != NULL)
             {
                 UNLOCK(&iterator->previousNode->lock);
             }

             iterator->previousNode = iterator->node;
             iterator->node         = iterator->node->next;

             return IX_ETH_DB_SUCCESS;
         }
         else
         {
             /* last in chain, prepare for next bucket */
             iterator->bucketIndex++;
         }
     }

    /* try next used bucket */
     for (; iterator->bucketIndex < hashTable->numBuckets ; iterator->bucketIndex++)
     {
         HashNode **nodePtr = &(hashTable->hashBuckets[iterator->bucketIndex]);
         HashNode *node = *nodePtr;
 #if (CPU!=SIMSPARCSOLARIS) && !defined (__wince)
         if (((iterator->bucketIndex & IX_ETHDB_BUCKET_INDEX_MASK) == 0) &&
             (iterator->bucketIndex < (hashTable->numBuckets - IX_ETHDB_BUCKETPTR_AHEAD)))
         {
             /* preload next cache line (2 cache line ahead) */
             nodePtr += IX_ETHDB_BUCKETPTR_AHEAD;
             __asm__ ("pld [%0];\n": : "r" (nodePtr));
         }
 #endif
         if (node != NULL)
         {
             TRY_LOCK(&node->lock);

             /* unlock last one or two nodes in the previous chain */
             if (iterator->node != NULL)
             {
                 UNLOCK(&iterator->node->lock);

                 if (iterator->previousNode != NULL)
                 {
                     UNLOCK(&iterator->previousNode->lock);
                 }
             }

             /* redirect iterator */
             iterator->previousNode = NULL;
             iterator->node         = node;

             return IX_ETH_DB_SUCCESS;
         }
     }

     /* could not advance iterator */
     if (iterator->node != NULL)
     {
         UNLOCK(&iterator->node->lock);

         if (iterator->previousNode != NULL)
         {
             UNLOCK(&iterator->previousNode->lock);
         }

         iterator->node = NULL;
     }

     return IX_ETH_DB_END;
 }

 /**
  * @brief removes an entry pointed by an iterator
  *
  * @param hashTable iterated hash table
  * @param iterator iterator object
  *
  * Removes the entry currently pointed by the iterator and repositions the iterator
  * on the next valid entry (if any). Handles locking issues automatically and
  * implicitely grants write access lock to the new pointed entry.
  * Failures due to concurrent threads having write access locks in the same region
  * preserve the state of the database and the iterator object, leaving the caller
  * free to retry without loss of access. It is guaranteed that only the thread owning
  * the iterator can remove the object pointed by the iterator.
  *
  * @retval IX_ETH_DB_SUCCESS if removal has succeeded
  * @retval IX_ETH_DB_BUSY if a locking failure has occured, in which case the caller
  * should retry
  *
  * @internal
  */
 IxEthDBStatus ixEthDBRemoveEntryAtHashIterator(HashTable *hashTable, HashIterator *iterator)
 {
     HashIterator nextIteratorPos;
     LockStack locks;

     INIT_STACK(&locks);

     /* set initial bucket index for next position */
     nextIteratorPos.bucketIndex = iterator->bucketIndex;

     /* compute iterator position before removing anything and lock ahead */
     if (iterator->node->next != NULL)
     {
         PUSH_LOCK(&locks, &iterator->node->next->lock);

         /* reposition on the next node in the chain */
         nextIteratorPos.node         = iterator->node->next;
         nextIteratorPos.previousNode = iterator->previousNode;
     }
     else
     {
         /* try next chain - don't know yet if we'll find anything */
         nextIteratorPos.node = NULL;

         /* if we find something it's a chain head */
         nextIteratorPos.previousNode = NULL;

         /* browse up in the buckets to find a non-null chain */
         while (++nextIteratorPos.bucketIndex < hashTable->numBuckets)
         {
             nextIteratorPos.node = hashTable->hashBuckets[nextIteratorPos.bucketIndex];

             if (nextIteratorPos.node != NULL)
             {
                 /* found a non-empty chain, try to lock head */
                 PUSH_LOCK(&locks, &nextIteratorPos.node->lock);

                 break;
             }
         }
     }

     /* restore links over the to-be-deleted item */
     if (iterator->previousNode == NULL)
     {
         /* first in chain, lock bucket */
         PUSH_LOCK(&locks, &hashTable->bucketLocks[iterator->bucketIndex]);

         hashTable->hashBuckets[iterator->bucketIndex] = iterator->node->next;

         POP_LOCK(&locks);
     }
     else
     {
         /* relink */
         iterator->previousNode->next = iterator->node->next;

         /* unlock last remaining node in current chain when moving between chains */
         if (iterator->node->next == NULL)
         {
             UNLOCK(&iterator->previousNode->lock);
         }
     }

     /* delete entry */
     hashTable->freeFunction(iterator->node->data);
     ixEthDBFreeHashNode(iterator->node);

     /* reposition iterator */
     *iterator = nextIteratorPos;

     return IX_ETH_DB_SUCCESS;
 }

 /**
  * @}
  */
	/**
	* @file ethHash.c
	*
	* @brief Hashtable implementation
	*
	* @par
	* IXP400 SW Release version 2.0
	*
	* -- Copyright Notice --
	*
	* @par
	* Copyright 2001-2005, Intel Corporation.
	* All rights reserved.
	*
	* @par
	* 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 Intel Corporation nor the names of its contributors
	* may be used to endorse or promote products derived from this software
	* without specific prior written permission.
	*
	* @par
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
	*
	* @par
	* -- End of Copyright Notice --
	*/


	#include "IxEthDB_p.h"
	#include "IxEthDBLocks_p.h"

	/**
	* @addtogroup EthDB
	*
	* @{
	*/

	/**
	* @brief initializes a hash table object
	*
	* @param hashTable uninitialized hash table structure
	* @param numBuckets number of buckets to use
	* @param entryHashFunction hash function used
	* to hash entire hash node data block (for adding)
	* @param matchFunctions array of match functions, indexed on type,
	* used to differentiate records with the same hash value
	* @param freeFunction function used to free node data blocks
	*
	* Initializes the given hash table object.
	*
	* @internal
	*/
	void ixEthDBInitHash(HashTable *hashTable,
	UINT32 numBuckets,
	HashFunction entryHashFunction,
	MatchFunction *matchFunctions,
	FreeFunction freeFunction)
	{
	UINT32 bucketIndex;
	UINT32 hashSize = numBuckets * sizeof(HashNode *);

	/* entry hashing, matching and freeing methods */
	hashTable->entryHashFunction = entryHashFunction;
	hashTable->matchFunctions = matchFunctions;
	hashTable->freeFunction = freeFunction;

	/* buckets */
	hashTable->numBuckets = numBuckets;

	/* set to 0 all buckets */
	memset(hashTable->hashBuckets, 0, hashSize);

	/* init bucket locks - note that initially all mutexes are unlocked after MutexInit()*/
	for (bucketIndex = 0 ; bucketIndex < numBuckets ; bucketIndex++)
	{
	ixOsalFastMutexInit(&hashTable->bucketLocks[bucketIndex]);
	}
	}

	/**
	* @brief adds an entry to the hash table
	*
	* @param hashTable hash table to add the entry to
	* @param entry entry to add
	*
	* The entry will be hashed using the entry hashing function and added to the
	* hash table, unless a locking blockage occurs, in which case the caller
	* should retry.
	*
	* @retval IX_ETH_DB_SUCCESS if adding <i>entry</i> has succeeded
	* @retval IX_ETH_DB_NOMEM if there's no memory left in the hash node pool
	* @retval IX_ETH_DB_BUSY if there's a locking failure on the insertion path
	*
	* @internal
	*/
	IX_ETH_DB_PUBLIC IxEthDBStatus ixEthDBAddHashEntry(HashTable hashTable, void entry)
	{
	UINT32 hashValue = hashTable->entryHashFunction(entry);
	UINT32 bucketIndex = hashValue % hashTable->numBuckets;
	HashNode *bucket = hashTable->hashBuckets[bucketIndex];
	HashNode *newNode;

	LockStack locks;

	INIT_STACK(&locks);

	/* lock bucket */
	PUSH_LOCK(&locks, &hashTable->bucketLocks[bucketIndex]);

	/* lock insertion element (first in chain), if any */
	if (bucket != NULL)
	{
	PUSH_LOCK(&locks, &bucket->lock);
	}

	/* get new node */
	newNode = ixEthDBAllocHashNode();

	if (newNode == NULL)
	{
	/* unlock everything */
	UNROLL_STACK(&locks);

	return IX_ETH_DB_NOMEM;
	}

	/* init lock - note that mutexes are unlocked after MutexInit */
	ixOsalFastMutexInit(&newNode->lock);

	/* populate new link */
	newNode->data = entry;

	/* add to bucket */
	newNode->next = bucket;
	hashTable->hashBuckets[bucketIndex] = newNode;

	/* unlock bucket and insertion point */
	UNROLL_STACK(&locks);

	return IX_ETH_DB_SUCCESS;
	}

	/**
	* @brief removes an entry from the hashtable
	*
	* @param hashTable hash table to remove entry from
	* @param keyType type of record key used for matching
	* @param reference reference key used to identify the entry
	*
	* The reference key will be hashed using the key hashing function,
	* the entry is searched using the hashed value and then examined
	* against the reference entry using the match function. A positive
	* match will trigger the deletion of the entry.
	* Locking failures are reported and the caller should retry.
	*
	* @retval IX_ETH_DB_SUCCESS if the removal was successful
	* @retval IX_ETH_DB_NO_SUCH_ADDR if the entry was not found
	* @retval IX_ETH_DB_BUSY if a locking failure occured during the process
	*
	* @internal
	*/
	IxEthDBStatus ixEthDBRemoveHashEntry(HashTable hashTable, int keyType, void reference)
	{
	UINT32 hashValue = hashTable->entryHashFunction(reference);
	UINT32 bucketIndex = hashValue % hashTable->numBuckets;
	HashNode *node = hashTable->hashBuckets[bucketIndex];
	HashNode *previousNode = NULL;

	LockStack locks;

	INIT_STACK(&locks);

	while (node != NULL)
	{
	/* try to lock node */
	PUSH_LOCK(&locks, &node->lock);

	if (hashTable->matchFunctions[keyType](reference, node->data))
	{
	/* found entry */
	if (node->next != NULL)
	{
	PUSH_LOCK(&locks, &node->next->lock);
	}

	if (previousNode == NULL)
	{
	/* node is head of chain */
	PUSH_LOCK(&locks, &hashTable->bucketLocks[bucketIndex]);

	hashTable->hashBuckets[bucketIndex] = node->next;

	POP_LOCK(&locks);
	}
	else
	{
	/* relink */
	previousNode->next = node->next;
	}

	UNROLL_STACK(&locks);

	/* free node */
	hashTable->freeFunction(node->data);
	ixEthDBFreeHashNode(node);

	return IX_ETH_DB_SUCCESS;
	}
	else
	{
	if (previousNode != NULL)
	{
	/* unlock previous node */
	SHIFT_STACK(&locks);
	}

	/* advance to next element in chain */
	previousNode = node;
	node = node->next;
	}
	}

	UNROLL_STACK(&locks);

	/* not found */
	return IX_ETH_DB_NO_SUCH_ADDR;
	}

	/**
	* @brief retrieves an entry from the hash table
	*
	* @param hashTable hash table to perform the search into
	* @param reference search key (a MAC address)
	* @param keyType type of record key used for matching
	* @param searchResult pointer where a reference to the located hash node
	* is placed
	*
	* Searches the entry with the same key as <i>reference</i> and places the
	* pointer to the resulting node in <i>searchResult</i>.
	* An implicit write access lock is granted after a search, which gives the
	* caller the opportunity to modify the entry.
	* Access should be released as soon as possible using @ref ixEthDBReleaseHashNode().
	*
	* @see ixEthDBReleaseHashNode()
	*
	* @retval IX_ETH_DB_SUCCESS if the search was completed successfully
	* @retval IX_ETH_DB_NO_SUCH_ADDRESS if no entry with the given key was found
	* @retval IX_ETH_DB_BUSY if a locking failure has occured, in which case
	* the caller should retry
	*
	* @warning unless the return value is <b>IX_ETH_DB_SUCCESS</b> the searchResult
	* location is NOT modified and therefore using a NULL comparison test when the
	* value was not properly initialized would be an error
	*
	* @internal
	*/
	IxEthDBStatus ixEthDBSearchHashEntry(HashTable hashTable, int keyType, void reference, HashNode **searchResult)
	{
	UINT32 hashValue;
	HashNode *node;

	hashValue = hashTable->entryHashFunction(reference);
	node = hashTable->hashBuckets[hashValue % hashTable->numBuckets];

	while (node != NULL)
	{
	TRY_LOCK(&node->lock);

	if (hashTable->matchFunctions[keyType](reference, node->data))
	{
	*searchResult = node;

	return IX_ETH_DB_SUCCESS;
	}
	else
	{
	UNLOCK(&node->lock);

	node = node->next;
	}
	}

	/* not found */
	return IX_ETH_DB_NO_SUCH_ADDR;
	}

	/**
	* @brief reports the existence of an entry in the hash table
	*
	* @param hashTable hash table to perform the search into
	* @param reference search key (a MAC address)
	* @param keyType type of record key used for matching
	*
	* Searches the entry with the same key as <i>reference</i>.
	* No implicit write access lock is granted after a search, hence the
	* caller cannot access or modify the entry. The result is only temporary.
	*
	* @see ixEthDBReleaseHashNode()
	*
	* @retval IX_ETH_DB_SUCCESS if the search was completed successfully
	* @retval IX_ETH_DB_NO_SUCH_ADDRESS if no entry with the given key was found
	* @retval IX_ETH_DB_BUSY if a locking failure has occured, in which case
	* the caller should retry
	*
	* @internal
	*/
	IxEthDBStatus ixEthDBPeekHashEntry(HashTable hashTable, int keyType, void reference)
	{
	UINT32 hashValue;
	HashNode *node;

	hashValue = hashTable->entryHashFunction(reference);
	node = hashTable->hashBuckets[hashValue % hashTable->numBuckets];

	while (node != NULL)
	{
	TRY_LOCK(&node->lock);

	if (hashTable->matchFunctions[keyType](reference, node->data))
	{
	UNLOCK(&node->lock);

	return IX_ETH_DB_SUCCESS;
	}
	else
	{
	UNLOCK(&node->lock);

	node = node->next;
	}
	}

	/* not found */
	return IX_ETH_DB_NO_SUCH_ADDR;
	}

	/**
	* @brief releases the write access lock
	*
	* @pre the node should have been obtained via @ref ixEthDBSearchHashEntry()
	*
	* @see ixEthDBSearchHashEntry()
	*
	* @internal
	*/
	void ixEthDBReleaseHashNode(HashNode *node)
	{
	UNLOCK(&node->lock);
	}

	/**
	* @brief initializes a hash iterator
	*
	* @param hashTable hash table to be iterated
	* @param iterator iterator object
	*
	* If the initialization is successful the iterator will point to the
	* first hash table record (if any).
	* Testing if the iterator has not passed the end of the table should be
	* done using the IS_ITERATOR_VALID(iteratorPtr) macro.
	* An implicit write access lock is granted on the entry pointed by the iterator.
	* The access is automatically revoked when the iterator is incremented.
	* If the caller decides to terminate the iteration before the end of the table is
	* passed then the manual access release method, @ref ixEthDBReleaseHashIterator,
	* must be called.
	*
	* @see ixEthDBReleaseHashIterator()
	*
	* @retval IX_ETH_DB_SUCCESS if initialization was successful and the iterator points
	* to the first valid table node
	* @retval IX_ETH_DB_FAIL if the table is empty
	* @retval IX_ETH_DB_BUSY if a locking failure has occured, in which case the caller
	* should retry
	*
	* @warning do not use ixEthDBReleaseHashNode() on entries pointed by the iterator, as this
	* might place the database in a permanent invalid lock state
	*
	* @internal
	*/
	IxEthDBStatus ixEthDBInitHashIterator(HashTable hashTable, HashIterator iterator)
	{
	iterator->bucketIndex = 0;
	iterator->node = NULL;
	iterator->previousNode = NULL;

	return ixEthDBIncrementHashIterator(hashTable, iterator);
	}

	/**
	* @brief releases the write access locks of the iterator nodes
	*
	* @warning use of this function is required only when the caller terminates an iteration
	* before reaching the end of the table
	*
	* @see ixEthDBInitHashIterator()
	* @see ixEthDBIncrementHashIterator()
	*
	* @param iterator iterator whose node(s) should be unlocked
	*
	* @internal
	*/
	void ixEthDBReleaseHashIterator(HashIterator *iterator)
	{
	if (iterator->previousNode != NULL)
	{
	UNLOCK(&iterator->previousNode->lock);
	}

	if (iterator->node != NULL)
	{
	UNLOCK(&iterator->node->lock);
	}
	}

	/**
	* @brief incremenents an iterator so that it points to the next valid entry of the table
	* (if any)
	*
	* @param hashTable hash table to iterate
	* @param iterator iterator object
	*
	* @pre the iterator object must be initialized using @ref ixEthDBInitHashIterator()
	*
	* If the increment operation is successful the iterator will point to the
	* next hash table record (if any).
	* Testing if the iterator has not passed the end of the table should be
	* done using the IS_ITERATOR_VALID(iteratorPtr) macro.
	* An implicit write access lock is granted on the entry pointed by the iterator.
	* The access is automatically revoked when the iterator is re-incremented.
	* If the caller decides to terminate the iteration before the end of the table is
	* passed then the manual access release method, @ref ixEthDBReleaseHashIterator,
	* must be called.
	* Is is guaranteed that no other thread can remove or change the iterated entry until
	* the iterator is incremented successfully.
	*
	* @see ixEthDBReleaseHashIterator()
	*
	* @retval IX_ETH_DB_SUCCESS if the operation was successful and the iterator points
	* to the next valid table node
	* @retval IX_ETH_DB_FAIL if the iterator has passed the end of the table
	* @retval IX_ETH_DB_BUSY if a locking failure has occured, in which case the caller
	* should retry
	*
	* @warning do not use ixEthDBReleaseHashNode() on entries pointed by the iterator, as this
	* might place the database in a permanent invalid lock state
	*
	* @internal
	*/
	IxEthDBStatus ixEthDBIncrementHashIterator(HashTable hashTable, HashIterator iterator)
	{
	/* unless iterator is just initialized... */
	if (iterator->node != NULL)
	{
	/* try next in chain */
	if (iterator->node->next != NULL)
	{
	TRY_LOCK(&iterator->node->next->lock);

	if (iterator->previousNode != NULL)
	{
	UNLOCK(&iterator->previousNode->lock);
	}

	iterator->previousNode = iterator->node;
	iterator->node = iterator->node->next;

	return IX_ETH_DB_SUCCESS;
	}
	else
	{
	/* last in chain, prepare for next bucket */
	iterator->bucketIndex++;
	}
	}

	/* try next used bucket */
	for (; iterator->bucketIndex < hashTable->numBuckets ; iterator->bucketIndex++)
	{
	HashNode **nodePtr = &(hashTable->hashBuckets[iterator->bucketIndex]);
	HashNode node = nodePtr;
	#if (CPU!=SIMSPARCSOLARIS) && !defined (__wince)
	if (((iterator->bucketIndex & IX_ETHDB_BUCKET_INDEX_MASK) == 0) &&
	(iterator->bucketIndex < (hashTable->numBuckets - IX_ETHDB_BUCKETPTR_AHEAD)))
	{
	/* preload next cache line (2 cache line ahead) */
	nodePtr += IX_ETHDB_BUCKETPTR_AHEAD;
	__asm__ ("pld [%0];\n": : "r" (nodePtr));
	}
	#endif
	if (node != NULL)
	{
	TRY_LOCK(&node->lock);

	/* unlock last one or two nodes in the previous chain */
	if (iterator->node != NULL)
	{
	UNLOCK(&iterator->node->lock);

	if (iterator->previousNode != NULL)
	{
	UNLOCK(&iterator->previousNode->lock);
	}
	}

	/* redirect iterator */
	iterator->previousNode = NULL;
	iterator->node = node;

	return IX_ETH_DB_SUCCESS;
	}
	}

	/* could not advance iterator */
	if (iterator->node != NULL)
	{
	UNLOCK(&iterator->node->lock);

	if (iterator->previousNode != NULL)
	{
	UNLOCK(&iterator->previousNode->lock);
	}

	iterator->node = NULL;
	}

	return IX_ETH_DB_END;
	}

	/**
	* @brief removes an entry pointed by an iterator
	*
	* @param hashTable iterated hash table
	* @param iterator iterator object
	*
	* Removes the entry currently pointed by the iterator and repositions the iterator
	* on the next valid entry (if any). Handles locking issues automatically and
	* implicitely grants write access lock to the new pointed entry.
	* Failures due to concurrent threads having write access locks in the same region
	* preserve the state of the database and the iterator object, leaving the caller
	* free to retry without loss of access. It is guaranteed that only the thread owning
	* the iterator can remove the object pointed by the iterator.
	*
	* @retval IX_ETH_DB_SUCCESS if removal has succeeded
	* @retval IX_ETH_DB_BUSY if a locking failure has occured, in which case the caller
	* should retry
	*
	* @internal
	*/
	IxEthDBStatus ixEthDBRemoveEntryAtHashIterator(HashTable hashTable, HashIterator iterator)
	{
	HashIterator nextIteratorPos;
	LockStack locks;

	INIT_STACK(&locks);

	/* set initial bucket index for next position */
	nextIteratorPos.bucketIndex = iterator->bucketIndex;

	/* compute iterator position before removing anything and lock ahead */
	if (iterator->node->next != NULL)
	{
	PUSH_LOCK(&locks, &iterator->node->next->lock);

	/* reposition on the next node in the chain */
	nextIteratorPos.node = iterator->node->next;
	nextIteratorPos.previousNode = iterator->previousNode;
	}
	else
	{
	/* try next chain - don't know yet if we'll find anything */
	nextIteratorPos.node = NULL;

	/* if we find something it's a chain head */
	nextIteratorPos.previousNode = NULL;

	/* browse up in the buckets to find a non-null chain */
	while (++nextIteratorPos.bucketIndex < hashTable->numBuckets)
	{
	nextIteratorPos.node = hashTable->hashBuckets[nextIteratorPos.bucketIndex];

	if (nextIteratorPos.node != NULL)
	{
	/* found a non-empty chain, try to lock head */
	PUSH_LOCK(&locks, &nextIteratorPos.node->lock);

	break;
	}
	}
	}

	/* restore links over the to-be-deleted item */
	if (iterator->previousNode == NULL)
	{
	/* first in chain, lock bucket */
	PUSH_LOCK(&locks, &hashTable->bucketLocks[iterator->bucketIndex]);

	hashTable->hashBuckets[iterator->bucketIndex] = iterator->node->next;

	POP_LOCK(&locks);
	}
	else
	{
	/* relink */
	iterator->previousNode->next = iterator->node->next;

	/* unlock last remaining node in current chain when moving between chains */
	if (iterator->node->next == NULL)
	{
	UNLOCK(&iterator->previousNode->lock);
	}
	}

	/* delete entry */
	hashTable->freeFunction(iterator->node->data);
	ixEthDBFreeHashNode(iterator->node);

	/* reposition iterator */
	*iterator = nextIteratorPos;

	return IX_ETH_DB_SUCCESS;
	}

	/**
	* @}
	*/