reactos/lib/3rdparty/fullfat/ff_hash.c

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/*****************************************************************************
* FullFAT - High Performance, Thread-Safe Embedded FAT File-System *
* Copyright (C) 2009 James Walmsley (james@worm.me.uk) *
* *
* This program is free software: you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation, either version 3 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/>. *
* *
* IMPORTANT NOTICE: *
* ================= *
* Alternative Licensing is available directly from the Copyright holder, *
* (James Walmsley). For more information consult LICENSING.TXT to obtain *
* a Commercial license. *
* *
* See RESTRICTIONS.TXT for extra restrictions on the use of FullFAT. *
* *
* Removing the above notice is illegal and will invalidate this license. *
*****************************************************************************
* See http://worm.me.uk/fullfat for more information. *
* Or http://fullfat.googlecode.com/ for latest releases and the wiki. *
*****************************************************************************/
/**
* @file ff_hash.c
* @author James Walmsley
* @ingroup HASH
*
* @defgroup HASH HASH Table
* @brief Provides a simple HASH lookup table.
*
**/
#include "ff_hash.h"
#include <stdlib.h>
#include <string.h>
#ifdef FF_HASH_CACHE
struct _FF_HASH_TABLE {
FF_T_UINT8 bitTable[FF_HASH_TABLE_SIZE];
};
/**
*
*
**/
FF_HASH_TABLE FF_CreateHashTable() {
FF_HASH_TABLE pHash = (FF_HASH_TABLE) FF_MALLOC(sizeof(struct _FF_HASH_TABLE));
if(pHash) {
FF_ClearHashTable(pHash);
return pHash;
}
return NULL;
}
FF_ERROR FF_ClearHashTable(FF_HASH_TABLE pHash) {
if(pHash) {
memset(pHash->bitTable, 0, FF_HASH_TABLE_SIZE);
return FF_ERR_NONE;
}
return FF_ERR_NULL_POINTER;
}
FF_ERROR FF_SetHash(FF_HASH_TABLE pHash, FF_T_UINT32 nHash) {
FF_T_UINT32 tblIndex = ((nHash / 8) % FF_HASH_TABLE_SIZE);
FF_T_UINT32 tblBit = nHash % 8;
if(pHash) {
pHash->bitTable[tblIndex] |= (0x80 >> tblBit);
return FF_ERR_NONE;
}
return FF_ERR_NULL_POINTER;
}
FF_ERROR FF_ClearHash(FF_HASH_TABLE pHash, FF_T_UINT32 nHash) {
FF_T_UINT32 tblIndex = ((nHash / 8) % FF_HASH_TABLE_SIZE);
FF_T_UINT32 tblBit = nHash % 8;
if(pHash) {
pHash->bitTable[tblIndex] &= ~(0x80 >> tblBit);
return FF_ERR_NONE;
}
return FF_ERR_NULL_POINTER;
}
FF_T_BOOL FF_isHashSet(FF_HASH_TABLE pHash, FF_T_UINT32 nHash) {
FF_T_UINT32 tblIndex = ((nHash / 8) % FF_HASH_TABLE_SIZE);
FF_T_UINT32 tblBit = nHash % 8;
if(pHash) {
if(pHash->bitTable[tblIndex] & (0x80 >> tblBit)) {
return FF_TRUE;
}
}
return FF_FALSE;
}
FF_ERROR FF_DestroyHashTable(FF_HASH_TABLE pHash) {
if(pHash) {
FF_FREE(pHash);
return FF_ERR_NONE;
}
return FF_ERR_NULL_POINTER;
}
#endif