417 lines
9 KiB
C
417 lines
9 KiB
C
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/*++
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Copyright (c) 1999, Microsoft Corporation
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Module Name:
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sample\hashtable.c
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Abstract:
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The file contains a hash table implementation.
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--*/
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#include "pchsample.h"
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#pragma hdrstop
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DWORD
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HT_Create(
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IN HANDLE hHeap,
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IN ULONG ulNumBuckets,
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IN PDISPLAY_FUNCTION pfnDisplay OPTIONAL,
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IN PFREE_FUNCTION pfnFree,
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IN PHASH_FUNCTION pfnHash,
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IN PCOMPARE_FUNCTION pfnCompare,
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OUT PHASH_TABLE *pphtHashTable)
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/*++
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Routine Description
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Creates a hash table.
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Locks
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None
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Arguments
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hHeap heap to use for allocation
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ulNumBuckets # buckets in the hash table
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pfnDisplay function used to display a hash table entry
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pfnFree function used to free a hash table entry
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pfnHash function used to compute the hash of an entry
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pfnCompare function used to compare two hash table entries
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pphtHashTable pointer to the hash table address
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Return Value
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NO_ERROR if success
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Failure code o/w
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--*/
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{
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DWORD dwErr = NO_ERROR;
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ULONG i = 0, ulSize = 0;
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PHASH_TABLE phtTable;
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// validate parameters
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if (!hHeap or
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!ulNumBuckets or
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!pfnFree or
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!pfnHash or
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!pfnCompare or
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!pphtHashTable)
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return ERROR_INVALID_PARAMETER;
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*pphtHashTable = NULL;
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do // breakout loop
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{
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// allocate the hash table structure
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ulSize = sizeof(HASH_TABLE);
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phtTable = HeapAlloc(hHeap, 0, ulSize);
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if (phtTable is NULL)
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{
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dwErr = GetLastError();
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break;
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}
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// allocate the buckets
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ulSize = ulNumBuckets * sizeof(LIST_ENTRY);
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phtTable->pleBuckets = HeapAlloc(hHeap, 0, ulSize);
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if (phtTable->pleBuckets is NULL)
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{
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HeapFree(hHeap, 0, phtTable); // undo allocation
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dwErr = GetLastError();
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break;
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}
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// initialize the buckets
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for (i = 0; i < ulNumBuckets; i++)
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InitializeListHead(phtTable->pleBuckets + i);
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// initialize the hash table structure's members
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phtTable->ulNumBuckets = ulNumBuckets;
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phtTable->ulNumEntries = 0;
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phtTable->pfnDisplay = pfnDisplay;
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phtTable->pfnFree = pfnFree;
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phtTable->pfnHash = pfnHash;
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phtTable->pfnCompare = pfnCompare;
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*pphtHashTable = phtTable;
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} while (FALSE);
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return dwErr;
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}
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DWORD
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HT_Destroy(
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IN HANDLE hHeap,
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IN PHASH_TABLE phtHashTable)
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/*++
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Routine Description
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Destroys a hash table.
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Frees up memory allocated for hash table entries.
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Locks
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Assumes the hash table is locked for writing.
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Arguments
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hHeap heap to use for deallocation
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phtHashTable pointer to the hash table to be destroyed
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Return Value
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NO_ERROR always
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--*/
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{
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ULONG i;
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PLIST_ENTRY pleList = NULL;
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// validate parameters
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if (!hHeap or
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!phtHashTable)
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return NO_ERROR;
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// deallocate the entries
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for (i = 0; i < phtHashTable->ulNumBuckets; i++)
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{
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pleList = phtHashTable->pleBuckets + i;
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FreeList(pleList, phtHashTable->pfnFree);
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}
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// deallocate the buckets
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HeapFree(hHeap, 0, phtHashTable->pleBuckets);
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// deallocate the hash table structure
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HeapFree(hHeap, 0, phtHashTable);
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return NO_ERROR;
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}
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DWORD
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HT_Cleanup(
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IN PHASH_TABLE phtHashTable)
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/*++
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Routine Description
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Cleans up all hash table entries.
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Locks
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Assumes the hash table is locked for writing.
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Arguments
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phtHashTable pointer to the hash table to be cleaned up
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Return Value
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NO_ERROR always
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--*/
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{
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ULONG i;
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PLIST_ENTRY pleList = NULL;
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// validate parameters
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if (!phtHashTable)
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return NO_ERROR;
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// deallocate the entries
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for (i = 0; i < phtHashTable->ulNumBuckets; i++)
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{
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pleList = phtHashTable->pleBuckets + i;
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FreeList(pleList, phtHashTable->pfnFree);
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}
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phtHashTable->ulNumEntries = 0;
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return NO_ERROR;
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}
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DWORD
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HT_InsertEntry(
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IN PHASH_TABLE phtHashTable,
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IN PLIST_ENTRY pleEntry)
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/*++
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Routine Description
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Inserts the specified entry in the hash table.
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Memory for the entry should already have been allocated.
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Locks
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Assumes the hash table is locked for writing.
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Arguments
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phtHashTable pointer to the hash table to be modified
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pleEntry entry to be inserted
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Return Value
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NO_ERROR if success
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Error code o/w (entry exists)
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--*/
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{
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DWORD dwErr = NO_ERROR;
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PLIST_ENTRY pleList = NULL;
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// validate parameters
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if (!phtHashTable or !pleEntry)
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return ERROR_INVALID_PARAMETER;
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do // breakout loop
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{
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// entry exists, fail
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if (HT_IsPresentEntry(phtHashTable, pleEntry))
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{
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dwErr = ERROR_INVALID_PARAMETER;
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break;
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}
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// insert the entry in the hash table
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pleList = phtHashTable->pleBuckets +
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(*phtHashTable->pfnHash)(pleEntry);
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InsertHeadList(pleList, pleEntry);
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phtHashTable->ulNumEntries++;
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} while (FALSE);
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return dwErr;
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}
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DWORD
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HT_GetEntry(
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IN PHASH_TABLE phtHashTable,
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IN PLIST_ENTRY pleKey,
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OUT PLIST_ENTRY *ppleEntry)
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/*++
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Routine Description
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Gets the hash table entry with the given key.
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Locks
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Assumes the hash table is locked for reading.
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Arguments
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phtHashTable pointer to the hash table to be searched
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pleKey key to be searched for
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ppleEntry pointer to matching entry's address
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Return Value
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NO_ERROR entry exisits
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ERROR_INVALID_PARAMETER o/w (entry does not exist)
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--*/
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{
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DWORD dwErr = NO_ERROR;
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PLIST_ENTRY pleList = NULL;
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// validate parameters
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if (!phtHashTable or !pleKey or !ppleEntry)
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return ERROR_INVALID_PARAMETER;
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pleList = phtHashTable->pleBuckets +
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(*phtHashTable->pfnHash)(pleKey);
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FindList(pleList, pleKey, ppleEntry, phtHashTable->pfnCompare);
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// entry not found, fail
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if (*ppleEntry is NULL)
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dwErr = ERROR_INVALID_PARAMETER;
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return dwErr;
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}
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DWORD
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HT_DeleteEntry(
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IN PHASH_TABLE phtHashTable,
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IN PLIST_ENTRY pleKey,
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OUT PLIST_ENTRY *ppleEntry)
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/*++
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Routine Description
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Deletes the entry with the given key from the hash table.
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Memory for the entry is not deleted.
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Locks
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Assumes the hash table is locked for writing.
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Arguments
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phtHashTable pointer to the hash table to be searched
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pleKey key to be deleted
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ppleEntry pointer to matching entry's address
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Return Value
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NO_ERROR entry exisits
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ERROR_INVALID_PARAMETER o/w (entry does not exist)
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--*/
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{
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DWORD dwErr = NO_ERROR;
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// validate parameters
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if (!phtHashTable or !pleKey or !ppleEntry)
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return ERROR_INVALID_PARAMETER;
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do // breakout loop
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{
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dwErr = HT_GetEntry(phtHashTable, pleKey, ppleEntry);
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// entry not found, fail
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if (dwErr != NO_ERROR)
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break;
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// entry found, delete from hash table and reset pointers
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RemoveEntryList(*ppleEntry);
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phtHashTable->ulNumEntries--;
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} while (FALSE);
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return dwErr;
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}
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BOOL
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HT_IsPresentEntry(
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IN PHASH_TABLE phtHashTable,
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IN PLIST_ENTRY pleKey)
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/*++
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Routine Description
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Is key present in the hash table?
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Locks
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Assumes the hash table is locked for reading.
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Arguments
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phtHashTable pointer to the hash table to be searched
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pleKey key to be deleted
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Return Value
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TRUE entry exisits
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FALSE o/w
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--*/
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{
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DWORD dwErr;
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PLIST_ENTRY pleEntry = NULL;
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// validate parameters
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if (!phtHashTable or !pleKey)
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return FALSE;
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dwErr = HT_GetEntry(phtHashTable, pleKey, &pleEntry);
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// entry not found, fail
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if (dwErr != NO_ERROR)
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return FALSE;
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// entry found, delete from hash table
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return TRUE;
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}
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DWORD
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HT_MapCar(
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IN PHASH_TABLE phtHashTable,
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IN PVOID_FUNCTION pfnVoidFunction
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)
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/*++
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Routine Description
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Applies the specified function to all entries in a hash table.
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Locks
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Assumes the hash table is locked for reading.
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Arguments
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phtHashTable pointer to the hash table to be mapcar'ed
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pfnVoidFunction pointer to function to apply to all entries
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Return Value
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NO_ERROR always
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--*/
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{
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ULONG i;
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PLIST_ENTRY pleList = NULL;
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// validate parameters
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if (!phtHashTable or !pfnVoidFunction)
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return NO_ERROR;
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for (i = 0; i < phtHashTable->ulNumBuckets; i++)
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{
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pleList = phtHashTable->pleBuckets + i;
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MapCarList(pleList, pfnVoidFunction);
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}
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return NO_ERROR;
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}
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