hash-function.h

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * 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 <cstring>  // memcpy
#include "simple-ref-count.h"

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 (void) = 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)
  {
    return (*m_fp)(buffer, size);
  }
  void clear ()
  { }

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)
  {
    return (*m_fp)(buffer, size);
  }
  uint32_t GetHash32 (const char * buffer, const std::size_t size)
  {
    uint32_t hash32;
    uint64_t hash64 = GetHash64 (buffer, size);

    memcpy (&hash32, &hash64, sizeof (hash32));
    return hash32;
  }
  void clear ()
  { }

private:
  Hash64Function_ptr m_fp;  
};  // Hash64<Hash64Function_ptr>


}  // namespace Function

}  // namespace Hash

}  // namespace ns3

#endif /* HASHFUNCTION_H */