Hash.h

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/*
 * 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.
 *
 * Written (W) 2009 Soeren Sonnenburg
 * Copyright (C) 2009 Fraunhofer Institute FIRST and Max-Planck-Society
 *
 * The MD5 and Murmur hashing functions were integrated from public sources.
 * Their respective copyrights follow.
 *
 * MD5
 *
 * This code implements the MD5 message-digest algorithm.
 * The algorithm is due to Ron Rivest.  This code was
 * written by Colin Plumb in 1993, no copyright is claimed.
 * This code is in the public domain; do with it what you wish.
 *
 * Equivalent code is available from RSA Data Security, Inc.
 * This code has been tested against that, and is equivalent,
 * except that you don't need to include two pages of legalese
 * with every copy.
 *
 * To compute the message digest of a chunk of bytes, declare an
 * MD5Context structure, pass it to MD5Init, call MD5Update as
 * needed on buffers full of bytes, and then call MD5Final, which
 * will fill a supplied 16-byte array with the digest.
 *
 * MurmurHash2
 *
 * (C) Austin Appleby, released under the MIT License
 * 
 *  Note - This code makes a few assumptions about how your machine behaves -
 * 
 *  1. We can read a 4-byte value from any address without crashing
 *  2. It will not produce the same results on little-endian and big-endian
 *     machines.
 */

#ifndef HASH_H
#define HASH_H

#include <shogun/base/SGObject.h>
#include <shogun/lib/common.h>

namespace shogun
{
class CHash : public CSGObject
{
    public:
        CHash() {}
        virtual ~CHash() {}

        static uint32_t crc32(uint8_t *data, int32_t len);

        static void MD5(unsigned char *x, unsigned l, unsigned char *buf);

        static uint32_t MurmurHash2(uint8_t* data, int32_t len, uint32_t seed);

        static uint32_t IncrementalMurmurHash2(uint8_t data, uint32_t h);

        static uint32_t MurmurHashString(substring s, uint32_t h);

        inline virtual const char* get_name() const { return "Hash"; }

    protected:

#ifndef DOXYGEN_SHOULD_SKIP_THIS

        struct MD5Context {
            uint32_t buf[4];
            uint32_t bits[2];
            unsigned char in[64];
        };
#endif // DOXYGEN_SHOULD_SKIP_THIS

        static void MD5Init(struct MD5Context *context);

        static void MD5Update(struct MD5Context *context,
                unsigned char const *buf, unsigned len);

        static void MD5Final(unsigned char digest[16],
                struct MD5Context *context);
        static void MD5Transform(uint32_t buf[4], uint32_t const in[16]);
};
}
#endif