QueryKeys.cpp

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//
// QueryKeys.cpp
//
// Copyright (c) Shareaza Development Team, 2002-2005.
// This file is part of SHAREAZA (www.shareaza.com)
//
// Shareaza 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 2 of
// the License, or (at your option) any later version.
//
// Shareaza 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 Shareaza; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//

#include "StdAfx.h"
#include "shareaza.h"
#include "QueryKeys.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif


// CQueryKeys construction

CQueryKeys::CQueryKeys()
{
        m_nBits         = 12;
        m_nTable        = (DWORD)pow( 2, m_nBits );
        m_pTable        = new DWORD[ m_nTable ];
        m_pMap          = new DWORD[ m_nBits * 2 ];

        DWORD* pMap = m_pMap;

        srand( GetTickCount() );

        for ( DWORD nCount = m_nBits ; nCount ; nCount-- )
        {
                *pMap++ = 1 << ( rand() % 32 );
                *pMap++ = 1 << ( rand() % 32 );
        }

        BYTE* pFill = (BYTE*)m_pTable;

        for ( DWORD nCount = m_nTable ; nCount ; nCount-- )
        {
                *pFill++ = (BYTE)( rand() & 0xFF );
                *pFill++ = (BYTE)( rand() & 0xFF );
                *pFill++ = (BYTE)( rand() & 0xFF );
                *pFill++ = (BYTE)( rand() & 0xFF );
        }
}

CQueryKeys::~CQueryKeys()
{
        delete [] m_pMap;
        delete [] m_pTable;
}

// CQueryKeys create or lookup

DWORD CQueryKeys::Create(DWORD nAddress)
{
        DWORD* pMap = m_pMap;
        DWORD nHash = 0;

        for ( DWORD nCount = m_nBits, nBit = 1 ; nCount ; nCount--, nBit <<= 1 )
        {
                BOOL bOne = ( nAddress & (*pMap++) ) != 0;
                BOOL bTwo = ( nAddress & (*pMap++) ) != 0;
                if ( bOne ^ bTwo ) nHash |= nBit;
        }

        return m_pTable[ nHash & ( m_nTable - 1 ) ];
}

// CQueryKeys check

BOOL CQueryKeys::Check(DWORD nAddress, DWORD nKey)
{
        DWORD* pMap = m_pMap;
        DWORD nHash = 0;

        for ( DWORD nCount = m_nBits, nBit = 1 ; nCount ; nCount--, nBit <<= 1 )
        {
                BOOL bOne = ( nAddress & (*pMap++) ) != 0;
                BOOL bTwo = ( nAddress & (*pMap++) ) != 0;
                if ( bOne ^ bTwo ) nHash |= nBit;
        }

        return nKey == m_pTable[ nHash & ( m_nTable - 1 ) ];
}

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