TextClassificationSerial/superHash.cpp at master · mremad/TextClassificationSerial · GitHub

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//
// superHash.cpp
// text2
//
// Created by Moumen Mohamed on 6/15/14.
// Copyright (c) 2014 Moumen Mohamed. All rights reserved.
//

#include"SuperHash.h"

#undef get16bits
#if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__) \
|| defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
#defineget16bits(d) (*((constuint16_t *) (d)))
#endif

#if !defined (get16bits)
#defineget16bits(d) ((((uint32_t)(((constuint8_t *)(d))[1])) << 8)\
+(uint32_t)(((constuint8_t *)(d))[0]) )
#endif


SuperHash:: SuperHash()
{

}


uint32_tSuperHash::hash_inc(constchar * data, int len, uint32_t hash)
{
uint32_t tmp;
int rem;

if (len <= 0 || data == NULL) return0;

 rem = len & 3;
 len >>= 2;

/* Main loop */
for (;len > 0; len--) {
 hash += get16bits (data);
 tmp = (get16bits (data+2) << 11) ^ hash;
 hash = (hash << 16) ^ tmp;
 data += 2*sizeof (uint16_t);
 hash += hash >> 11;
 }

/* Handle end cases */
switch (rem) {
case3: hash += get16bits (data);
 hash ^= hash << 16;
 hash ^= data[sizeof (uint16_t)] << 18;
 hash += hash >> 11;
break;
case2: hash += get16bits (data);
 hash ^= hash << 11;
 hash += hash >> 17;
break;
case1: hash += *data;
 hash ^= hash << 10;
 hash += hash >> 1;
 }

/* Force "avalanching" of final 127 bits */
 hash ^= hash << 3;
 hash += hash >> 5;
 hash ^= hash << 4;
 hash += hash >> 17;
 hash ^= hash << 25;
 hash += hash >> 6;

return hash;
}

uint32_tSuperHash::create_hash(std::string data, int len, int tablesize)
{
char * charList= (char *)malloc(len*sizeof(char));
for(int i=0;i<len;i++)
 charList[i]= data[i];

uint32_t result= hash_inc(charList, len, (uint32_t) len);
free(charList);
return result%tablesize;
}