hash.h

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/*
 * /phoenix/include/common/hash.h
 *
 * This file is a part of Phoenix operating system.
 * Copyright (c) 2011-2012, Artyom Lebedev <artyom.lebedev@gmail.com>
 * All rights reserved.
 * See COPYING file for copyright details.
 */

#ifndef HASH_H_
#define HASH_H_

class Hash {
public:
    inline
    Hash(u32 initial = 0)
    {
        _a = _b = _c = INITIAL_VALUE + initial;
    }

    inline void
    Reset(u32 initial = 0)
    {
        _a = _b = _c = INITIAL_VALUE + initial;
        _resid = 0;
        _length = 0;
    }

    static void Mix(u32 &a, u32 &b, u32 &c);

    static void Final(u32 &a, u32 &b, u32 &c);

    void Feed(const void *data, size_t size);

    inline u32
    Get32()
    {
        u32 a, b, c;
        _Finalize(a, b, c);
        return c;
    }

    inline u64
    Get64()
    {
        u32 a, b, c;
        _Finalize(a, b, c);
        return (static_cast<u64>(b) << 32) | c;
    }

    inline
    operator u32()
    {
        return Get32();
    }

    inline
    operator u64()
    {
        return Get64();
    }

    inline size_t
    GetLength()
    {
        return _length;
    }

private:
    enum {
        INITIAL_VALUE = 0x9e3779b8,
    };
    u32 _a, _b, _c;
    size_t _resid = 0;
    size_t _length = 0;

    void _Finalize(u32 &a, u32 &b, u32 &c);
};


#endif /* HASH_H_ */