text: /* -*- 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 HASH_MURMUR3_H
  #define HASH_MURMUR3_H
  
  #include "hash-function.h"
  
  /**
   * \file
   * \ingroup hash
   * \brief ns3::Hash::Function::Murmur3 declaration.
   */
  
  namespace ns3 {
  
  namespace Hash {
  
  namespace Function {
  
  /**
   *  \ingroup hash
   *
   *  \brief Murmur3 hash function implementation
   *
   *  Adapted from http://code.google.com/p/smhasher/
   *
   *  MurmurHash3 was written by Austin Appleby, and is placed in the public
   *  domain. The author hereby disclaims copyright to this source code.
  
   *  Note - The x86 and x64 versions do _not_ produce the same results, as the
   *  algorithms are optimized for their respective platforms. You can still
   *  compile and run any of them on any platform, but your performance with the
   *  non-native version will be less than optimal.
   */
  class Murmur3 : public Implementation
  {
  public:
    /**
     * Constructor, clears internal state
     */
    Murmur3 ();
    /**
     * Compute 32-bit hash of a byte buffer
     *
     * Call clear () between calls to GetHash32() to reset the
     * internal state and hash each buffer separately.
     *
     * If you don't call clear() between calls to GetHash32,
     * you can hash successive buffers.  The final return value
     * will be the cumulative hash across all calls.
     *
     * \param [in] buffer pointer to the beginning of the buffer
     * \param [in] size length of the buffer, in bytes
     * \return 32-bit hash of the buffer
     */
    uint32_t  GetHash32  (const char * buffer, const size_t size);
    /**
     * Compute 64-bit hash of a byte buffer.
     *
     * Call clear () between calls to GetHash64() to reset the
     * internal state and hash each buffer separately.
     *
     * If you don't call clear() between calls to GetHash64,
     * you can hash successive buffers.  The final return value
     * will be the cumulative hash across all calls.
     *
     * \param [in] buffer pointer to the beginning of the buffer
     * \param [in] size length of the buffer, in bytes
     * \return 64-bit hash of the buffer
     */
    uint64_t  GetHash64  (const char * buffer, const size_t size);
    /**
     * Restore initial state
     */
    virtual void clear (void);
  
  private:
    /**
     * Seed value
     *
     * This has to be a constant for all MPI ranks to generate
     * the same hash from the same string.
     */
    enum seed
    {
      SEED = 0x8BADF00D  // Ate bad food
    };
    /** 
     * Cache last hash value, and total bytes hashed (needed to finalize),
     * for incremental hashing
     */
    /**@{*/
    uint32_t m_hash32;
    uint32_t m_size32;
    /**@}*/
    
    /** murmur3 produces 128-bit hash and state; we use just the first 64-bits. */
    /**@{*/
    uint64_t m_hash64[2];  
    uint64_t m_size64;
    /**@}*/
        
  };  // class Murmur3
  
  }  // namespace Function
  
  }  // namespace Hash
  
  }  // namespace ns3
  
  #endif  /* HASH_MURMUR3_H */
  