General Purpose Hash Function for C, C++

C나 C++로 Hash Function을 사용할 때 도움이 되길 바란다.
성능은 거의 차이가 없어 보인다. 이름이 맘에 드는 놈으로 잘 골라서 쓰길...

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C Implementation
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more..

GeneralHashFunctions.h

GeneralHashFunctions.h

/*
 **************************************************************************
 *                                                                        *
 *          General Purpose Hash Function Algorithms Library              *
 *                                                                        *
 * Author: Arash Partow - 2002                                            *
 * URL: http://www.partow.net                                             *
 * URL: http://www.partow.net/programming/hashfunctions/index.html        *
 *                                                                        *
 * Copyright notice:                                                      *
 * Free use of the General Purpose Hash Function Algorithms Library is    *
 * permitted under the guidelines and in accordance with the most current *
 * version of the Common Public License.                                  *
 * http://www.opensource.org/licenses/cpl.php                             *
 *                                                                        *
 **************************************************************************
*/

#ifndef INCLUDE_GENERALHASHFUNCTION_C_H
#define INCLUDE_GENERALHASHFUNCTION_C_H

#include <stdio.h>

typedef unsigned int (*hash_function)(char*, unsigned int len);
unsigned int RSHash  (char* str, unsigned int len);
unsigned int JSHash  (char* str, unsigned int len);
unsigned int PJWHash (char* str, unsigned int len);
unsigned int ELFHash (char* str, unsigned int len);
unsigned int BKDRHash(char* str, unsigned int len);
unsigned int SDBMHash(char* str, unsigned int len);
unsigned int DJBHash (char* str, unsigned int len);
unsigned int DEKHash (char* str, unsigned int len);
unsigned int BPHash  (char* str, unsigned int len);
unsigned int FNVHash (char* str, unsigned int len);
unsigned int APHash  (char* str, unsigned int len);

#endif

 

GeneralHashFunctions.c

GeneralHashFunctions.c

#include "GeneralHashFunctions.h"

unsigned int RSHash(char* str, unsigned int len)
{
   unsigned int b    = 378551;
   unsigned int a    = 63689;
   unsigned int hash = 0;
   unsigned int i    = 0;

   for(i = 0; i < len; str++, i++)
   {
      hash = hash * a + (*str);
      a    = a * b;
   }

   return hash;
}
/* End Of RS Hash Function */

unsigned int JSHash(char* str, unsigned int len)
{
   unsigned int hash = 1315423911;
   unsigned int i    = 0;

   for(i = 0; i < len; str++, i++)
   {
      hash ^= ((hash << 5) + (*str) + (hash >> 2));
   }

   return hash;
}
/* End Of JS Hash Function */

unsigned int PJWHash(char* str, unsigned int len)
{
   const unsigned int BitsInUnsignedInt = (unsigned int)(sizeof(unsigned int) * 8);
   const unsigned int ThreeQuarters     = (unsigned int)((BitsInUnsignedInt  * 3) / 4);
   const unsigned int OneEighth         = (unsigned int)(BitsInUnsignedInt / 8);
   const unsigned int HighBits          = (unsigned int)(0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth);
   unsigned int hash              = 0;
   unsigned int test              = 0;
   unsigned int i                 = 0;

   for(i = 0; i < len; str++, i++)
   {
      hash = (hash << OneEighth) + (*str);

      if((test = hash & HighBits)  != 0)
      {
         hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits));
      }
   }

   return hash;
}
/* End Of  P. J. Weinberger Hash Function */

unsigned int ELFHash(char* str, unsigned int len)
{
   unsigned int hash = 0;
   unsigned int x    = 0;
   unsigned int i    = 0;

   for(i = 0; i < len; str++, i++)
   {
      hash = (hash << 4) + (*str);
      if((x = hash & 0xF0000000L) != 0)
      {
         hash ^= (x >> 24);
      }
      hash &= ~x;
   }

   return hash;
}
/* End Of ELF Hash Function */

unsigned int BKDRHash(char* str, unsigned int len)
{
   unsigned int seed = 131; /* 31 131 1313 13131 131313 etc.. */
   unsigned int hash = 0;
   unsigned int i    = 0;

   for(i = 0; i < len; str++, i++)
   {
      hash = (hash * seed) + (*str);
   }

   return hash;
}
/* End Of BKDR Hash Function */

unsigned int SDBMHash(char* str, unsigned int len)
{
   unsigned int hash = 0;
   unsigned int i    = 0;

   for(i = 0; i < len; str++, i++)
   {
      hash = (*str) + (hash << 6) + (hash << 16) - hash;
   }

   return hash;
}
/* End Of SDBM Hash Function */

unsigned int DJBHash(char* str, unsigned int len)
{
   unsigned int hash = 5381;
   unsigned int i    = 0;

   for(i = 0; i < len; str++, i++)
   {
      hash = ((hash << 5) + hash) + (*str);
   }

   return hash;
}
/* End Of DJB Hash Function */

unsigned int DEKHash(char* str, unsigned int len)
{
   unsigned int hash = len;
   unsigned int i    = 0;

   for(i = 0; i < len; str++, i++)
   {
      hash = ((hash << 5) ^ (hash >> 27)) ^ (*str);
   }
   return hash;
}
/* End Of DEK Hash Function */

unsigned int BPHash(char* str, unsigned int len)
{
   unsigned int hash = 0;
   unsigned int i    = 0;
   for(i = 0; i < len; str++, i++)
   {
      hash = hash << 7 ^ (*str);
   }

   return hash;
}
/* End Of BP Hash Function */

unsigned int FNVHash(char* str, unsigned int len)
{
   const unsigned int fnv_prime = 0x811C9DC5;
   unsigned int hash      = 0;
   unsigned int i         = 0;

   for(i = 0; i < len; str++, i++)
   {
      hash *= fnv_prime;
      hash ^= (*str);
   }

   return hash;
}
/* End Of FNV Hash Function */

unsigned int APHash(char* str, unsigned int len)
{
   unsigned int hash = 0xAAAAAAAA;
   unsigned int i    = 0;

   for(i = 0; i < len; str++, i++)
   {
      hash ^= ((i & 1) == 0) ? (  (hash <<  7) ^ (*str) ^ (hash >> 3)) :
                               (~((hash << 11) ^ (*str) ^ (hash >> 5)));
   }

   return hash;
}
/* End Of AP Hash Function */

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C++ Implementation
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more..

GeneralHashFunctions.hpp

GeneralHashFunctions.hpp

/*
 **************************************************************************
 *                                                                        *
 *          General Purpose Hash Function Algorithms Library              *
 *                                                                        *
 * Author: Arash Partow - 2002                                            *
 * URL: http://www.partow.net                                             *
 * URL: http://www.partow.net/programming/hashfunctions/index.html        *
 *                                                                        *
 * Copyright notice:                                                      *
 * Free use of the General Purpose Hash Function Algorithms Library is    *
 * permitted under the guidelines and in accordance with the most current *
 * version of the Common Public License.                                  *
 * http://www.opensource.org/licenses/cpl.php                             *
 *                                                                        *
 **************************************************************************
*/

#ifndef INCLUDE_GENERALHASHFUNCTION_CPP_H
#define INCLUDE_GENERALHASHFUNCTION_CPP_H

#include <string>

typedef unsigned int (*HashFunction)(const std::string&);
unsigned int RSHash  (const std::string& str);
unsigned int JSHash  (const std::string& str);
unsigned int PJWHash (const std::string& str);
unsigned int ELFHash (const std::string& str);
unsigned int BKDRHash(const std::string& str);
unsigned int SDBMHash(const std::string& str);
unsigned int DJBHash (const std::string& str);
unsigned int DEKHash (const std::string& str);
unsigned int BPHash  (const std::string& str);
unsigned int FNVHash (const std::string& str);
unsigned int APHash  (const std::string& str);

#endif

GeneralHashFunctions.cpp

GeneralHashFunctions.cpp

#include "GeneralHashFunctions.h"

unsigned int RSHash(const std::string& str)
{
   unsigned int b    = 378551;
   unsigned int a    = 63689;
   unsigned int hash = 0;

   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash = hash * a + str[i];
      a    = a * b;
   }

   return hash;
}
/* End Of RS Hash Function */

unsigned int JSHash(const std::string& str)
{
   unsigned int hash = 1315423911;

   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash ^= ((hash << 5) + str[i] + (hash >> 2));
   }

   return hash;
}
/* End Of JS Hash Function */

unsigned int PJWHash(const std::string& str)
{
   unsigned int BitsInUnsignedInt = (unsigned int)(sizeof(unsigned int) * 8);
   unsigned int ThreeQuarters     = (unsigned int)((BitsInUnsignedInt  * 3) / 4);
   unsigned int OneEighth         = (unsigned int)(BitsInUnsignedInt / 8);
   unsigned int HighBits          = (unsigned int)(0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth);
   unsigned int hash              = 0;
   unsigned int test              = 0;

   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash = (hash << OneEighth) + str[i];

      if((test = hash & HighBits)  != 0)
      {
         hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits));
      }
   }

   return hash;
}
/* End Of  P. J. Weinberger Hash Function */

unsigned int ELFHash(const std::string& str)
{
   unsigned int hash = 0;
   unsigned int x    = 0;

   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash = (hash << 4) + str[i];
      if((x = hash & 0xF0000000L) != 0)
      {
         hash ^= (x >> 24);
      }
      hash &= ~x;
   }

   return hash;
}
/* End Of ELF Hash Function */

unsigned int BKDRHash(const std::string& str)
{
   unsigned int seed = 131; // 31 131 1313 13131 131313 etc..
   unsigned int hash = 0;

   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash = (hash * seed) + str[i];
   }

   return hash;
}
/* End Of BKDR Hash Function */

unsigned int SDBMHash(const std::string& str)
{
   unsigned int hash = 0;

   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash = str[i] + (hash << 6) + (hash << 16) - hash;
   }

   return hash;
}
/* End Of SDBM Hash Function */

unsigned int DJBHash(const std::string& str)
{
   unsigned int hash = 5381;

   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash = ((hash << 5) + hash) + str[i];
   }

   return hash;
}
/* End Of DJB Hash Function */

unsigned int DEKHash(const std::string& str)
{
   unsigned int hash = static_cast<unsigned int>(str.length());

   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash = ((hash << 5) ^ (hash >> 27)) ^ str[i];
   }

   return hash;
}
/* End Of DEK Hash Function */

unsigned int BPHash(const std::string& str)
{
   unsigned int hash = 0;
   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash = hash << 7 ^ str[i];
   }

   return hash;
}
/* End Of BP Hash Function */

unsigned int FNVHash(const std::string& str)
{
   const unsigned int fnv_prime = 0x811C9DC5;
   unsigned int hash = 0;
   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash *= fnv_prime;
      hash ^= str[i];
   }

   return hash;
}
/* End Of FNV Hash Function */

unsigned int APHash(const std::string& str)
{
   unsigned int hash = 0xAAAAAAAA;

   for(std::size_t i = 0; i < str.length(); i++)
   {
      hash ^= ((i & 1) == 0) ? (  (hash <<  7) ^ str[i] ^ (hash >> 3)) :
                               (~((hash << 11) ^ str[i] ^ (hash >> 5)));
   }

   return hash;
}
/* End Of AP Hash Function */