/*****************************************************************************
Copyright © 2006, 2007, The Board of Trustees of the University of Illinois.
All Rights Reserved.
National Center for Data Mining (NCDM)
University of Illinois at Chicago
http://www.ncdm.uic.edu/
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 2 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, write to the Free Software Foundation, Inc., 51
Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
*****************************************************************************/
/*****************************************************************************
written by
Yunhong Gu [gu@lac.uic.edu], last updated 02/23/2007
*****************************************************************************/
#ifndef __DHASH_H__
#define __DHASH_H__
#include <openssl/sha.h>
#include <math.h>
#include <string>
namespace cb
{
class DHash
{
public:
DHash(): m_im(32) {}
DHash(const int m): m_im(m) {}
~DHash() {}
unsigned int hash(const char* str)
{
unsigned char res[SHA_DIGEST_LENGTH];
SHA1((const unsigned char*)str, strlen(str), res);
return *(unsigned int*)(res + SHA_DIGEST_LENGTH - 4);
}
static unsigned int hash(const char* str, int m)
{
unsigned char res[SHA_DIGEST_LENGTH];
SHA1((const unsigned char*)str, strlen(str), res);
if (m >= 32)
return *(unsigned int*)(res + SHA_DIGEST_LENGTH - 4);
unsigned int mask = 1;
mask = (mask << m) - 1;
return (*(unsigned int*)(res + SHA_DIGEST_LENGTH - 4)) & mask;
}
private:
unsigned int m_im;
};
}; // namespace
#endif