85 lines
3.1 KiB
C
85 lines
3.1 KiB
C
|
// Copyright (c) 2010, Paul Hsieh
|
||
|
|
// All rights reserved.
|
||
|
|
//
|
||
|
|
// Redistribution and use in source and binary forms, with or without
|
||
|
|
// modification, are permitted provided that the following conditions are met:
|
||
|
|
//
|
||
|
|
// * Redistributions of source code must retain the above copyright notice, this
|
||
|
|
// list of conditions and the following disclaimer.
|
||
|
|
// * Redistributions in binary form must reproduce the above copyright notice,
|
||
|
|
// this list of conditions and the following disclaimer in the documentation
|
||
|
|
// and/or other materials provided with the distribution.
|
||
|
|
// * Neither my name, Paul Hsieh, nor the names of any other contributors to the
|
||
|
|
// code use may not be used to endorse or promote products derived from this
|
||
|
|
// software without specific prior written permission.
|
||
|
|
//
|
||
|
|
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
||
|
|
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
||
|
|
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
||
|
|
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
||
|
|
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
||
|
|
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
||
|
|
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
||
|
|
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
||
|
|
// POSSIBILITY OF SUCH DAMAGE.
|
||
|
|
|
||
|
|
#include <stdint.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
#undef get16bits
|
||
|
|
#if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__) \
|
||
|
|
|| defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
|
||
|
|
#define get16bits(d) (*((const uint16_t *) (d)))
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#if !defined (get16bits)
|
||
|
|
#define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
|
||
|
|
+(uint32_t)(((const uint8_t *)(d))[0]) )
|
||
|
|
#endif
|
||
|
|
|
||
|
|
uint32_t SuperFastHash (const char * data, int len) {
|
||
|
|
uint32_t hash = len, tmp;
|
||
|
|
int rem;
|
||
|
|
|
||
|
|
if (len <= 0 || data == NULL) return 0;
|
||
|
|
|
||
|
|
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) {
|
||
|
|
case 3: hash += get16bits (data);
|
||
|
|
hash ^= hash << 16;
|
||
|
|
hash ^= ((signed char)data[sizeof (uint16_t)]) << 18;
|
||
|
|
hash += hash >> 11;
|
||
|
|
break;
|
||
|
|
case 2: hash += get16bits (data);
|
||
|
|
hash ^= hash << 11;
|
||
|
|
hash += hash >> 17;
|
||
|
|
break;
|
||
|
|
case 1: hash += (signed char)*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;
|
||
|
|
}
|