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

   1 /*****************************************************************************
   2  *  FullFAT - High Performance, Thread-Safe Embedded FAT File-System         *
   3  *  Copyright (C) 2009  James Walmsley (james@worm.me.uk)                    *
   4  *                                                                           *
   5  *  This program is free software: you can redistribute it and/or modify     *
   6  *  it under the terms of the GNU General Public License as published by     *
   7  *  the Free Software Foundation, either version 3 of the License, or        *
   8  *  (at your option) any later version.                                      *
   9  *                                                                           *
  10  *  This program is distributed in the hope that it will be useful,          *
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of           *
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            *
  13  *  GNU General Public License for more details.                             *
  14  *                                                                           *
  15  *  You should have received a copy of the GNU General Public License        *
  16  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.    *
  17  *                                                                           *
  18  *  IMPORTANT NOTICE:                                                        *
  19  *  =================                                                        *
  20  *  Alternative Licensing is available directly from the Copyright holder,   *
  21  *  (James Walmsley). For more information consult LICENSING.TXT to obtain   *
  22  *  a Commercial license.                                                    *
  23  *                                                                           *
  24  *  See RESTRICTIONS.TXT for extra restrictions on the use of FullFAT.       *
  25  *                                                                           *
  26  *  Removing the above notice is illegal and will invalidate this license.   *
  27  *****************************************************************************
  28  *  See http://worm.me.uk/fullfat for more information.                      *
  29  *  Or  http://fullfat.googlecode.com/ for latest releases and the wiki.     *
  30  *****************************************************************************/
  31
  32 /**
  33  *      @file           ff_hash.c
  34  *      @author         James Walmsley
  35  *      @ingroup        HASH
  36  *
  37  *      @defgroup       HASH HASH Table
  38  *      @brief          Provides a simple HASH lookup table.
  39  *
  40  **/
  41
  42 #include "ff_hash.h"
  43 #include <stdlib.h>
  44 #include <string.h>
  45
  46 #ifdef FF_HASH_CACHE
  47 struct _FF_HASH_TABLE {
  48         FF_T_UINT8 bitTable[FF_HASH_TABLE_SIZE];
  49 };
  50
  51 /**
  52  *
  53  *
  54  **/
  55 FF_HASH_TABLE FF_CreateHashTable() {
  56         FF_HASH_TABLE pHash = (FF_HASH_TABLE) FF_MALLOC(sizeof(struct _FF_HASH_TABLE));
  57
  58         if(pHash) {
  59                 FF_ClearHashTable(pHash);
  60                 return pHash;
  61         }
  62
  63         return NULL;
  64 }
  65
  66 FF_ERROR FF_ClearHashTable(FF_HASH_TABLE pHash) {
  67         if(pHash) {
  68                 memset(pHash->bitTable, 0, FF_HASH_TABLE_SIZE);
  69                 return FF_ERR_NONE;
  70         }
  71
  72         return FF_ERR_NULL_POINTER;
  73 }
  74
  75 FF_ERROR FF_SetHash(FF_HASH_TABLE pHash, FF_T_UINT32 nHash) {
  76         FF_T_UINT32 tblIndex    = ((nHash / 8) % FF_HASH_TABLE_SIZE);
  77         FF_T_UINT32 tblBit              = nHash % 8;
  78
  79         if(pHash) {
  80                 pHash->bitTable[tblIndex] |= (0x80 >> tblBit);
  81                 return FF_ERR_NONE;
  82         }
  83
  84         return FF_ERR_NULL_POINTER;
  85 }
  86
  87 FF_ERROR FF_ClearHash(FF_HASH_TABLE pHash, FF_T_UINT32 nHash) {
  88         FF_T_UINT32 tblIndex    = ((nHash / 8) % FF_HASH_TABLE_SIZE);
  89         FF_T_UINT32 tblBit              = nHash % 8;
  90
  91         if(pHash) {
  92                 pHash->bitTable[tblIndex] &= ~(0x80 >> tblBit);
  93                 return FF_ERR_NONE;
  94         }
  95
  96         return FF_ERR_NULL_POINTER;
  97 }
  98
  99 FF_T_BOOL FF_isHashSet(FF_HASH_TABLE pHash, FF_T_UINT32 nHash) {
 100         FF_T_UINT32 tblIndex    = ((nHash / 8) % FF_HASH_TABLE_SIZE);
 101         FF_T_UINT32 tblBit              = nHash % 8;
 102
 103         if(pHash) {
 104                 if(pHash->bitTable[tblIndex] & (0x80 >> tblBit)) {
 105                         return FF_TRUE;
 106                 }
 107         }
 108         return FF_FALSE;
 109 }
 110
 111 FF_ERROR FF_DestroyHashTable(FF_HASH_TABLE pHash) {
 112         if(pHash) {
 113                 FF_FREE(pHash);
 114                 return FF_ERR_NONE;
 115         }
 116         return FF_ERR_NULL_POINTER;
 117 }
 118
 119 #endif