hash-function.h

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/*
 * Copyright (c) 2012 Lawrence Livermore National Laboratory
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Peter D. Barnes, Jr. <pdbarnes@llnl.gov>
 */
 
#ifndef HASHFUNCTION_H
#define HASHFUNCTION_H
 
#include "simple-ref-count.h"
 
#include <cstring> // memcpy
 
namespace ns3
{
 
namespace Hash
{
 
class Implementation : public SimpleRefCount<Implementation>
{
  public:
    virtual uint32_t GetHash32(const char* buffer, const std::size_t size) = 0;
    virtual uint64_t GetHash64(const char* buffer, const std::size_t size);
    virtual void clear() = 0;
 
    Implementation()
    {
    }
 
    virtual ~Implementation()
    {
    }
}; // Hashfunction
 
/*--------------------------------------
 *  Hash function implementation
 *  by function pointers and templates
 */
 
typedef uint32_t (*Hash32Function_ptr)(const char*, const std::size_t);
typedef uint64_t (*Hash64Function_ptr)(const char*, const std::size_t);
 
namespace Function
{
 
class Hash32 : public Implementation
{
  public:
    Hash32(Hash32Function_ptr hp)
        : m_fp(hp)
    {
    }
 
    uint32_t GetHash32(const char* buffer, const std::size_t size) override
    {
        return (*m_fp)(buffer, size);
    }
 
    void clear() override
    {
    }
 
  private:
    Hash32Function_ptr m_fp; 
};                           // Hash32
 
class Hash64 : public Implementation
{
  public:
    Hash64(Hash64Function_ptr hp)
        : m_fp(hp)
    {
    }
 
    uint64_t GetHash64(const char* buffer, const std::size_t size) override
    {
        return (*m_fp)(buffer, size);
    }
 
    uint32_t GetHash32(const char* buffer, const std::size_t size) override
    {
        uint32_t hash32;
        uint64_t hash64 = GetHash64(buffer, size);
 
        memcpy(&hash32, &hash64, sizeof(hash32));
        return hash32;
    }
 
    void clear() override
    {
    }
 
  private:
    Hash64Function_ptr m_fp; 
};                           // Hash64<Hash64Function_ptr>
 
} // namespace Function
 
} // namespace Hash
 
} // namespace ns3
 
#endif /* HASHFUNCTION_H */