cryb-to/lib/hash/pearson.c
Dag-Erling Smørgrav 0023f57ab5 Add a library of general (non-cryptographic) hash functions, currently
consisting of the Pearson string hash function and the Murmur3-32 hash
function.
2014-07-19 06:03:57 +00:00

97 lines
3.6 KiB
C

/*-
* Copyright (c) 2014 The University of Oslo
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 "cryb/impl.h"
#include <stdint.h>
#include <string.h>
#include <cryb/hash.h>
/*
* Implementation of the hash function described in Pearson, Peter
* K. (June 1990), "Fast Hashing of Variable-Length Text Strings",
* Communications of the ACM 33 (6): 677, doi:10.1145/78973.78978
*/
static const uint8_t T[256] = {
0x01, 0x57, 0x31, 0x0c, 0xb0, 0xb2, 0x66, 0xa6,
0x79, 0xc1, 0x06, 0x54, 0xf9, 0xe6, 0x2c, 0xa3,
0x0e, 0xc5, 0xd5, 0xb5, 0xa1, 0x55, 0xda, 0x50,
0x40, 0xef, 0x18, 0xe2, 0xec, 0x8e, 0x26, 0xc8,
0x6e, 0xb1, 0x68, 0x67, 0x8d, 0xfd, 0xff, 0x32,
0x4d, 0x65, 0x51, 0x12, 0x2d, 0x60, 0x1f, 0xde,
0x19, 0x6b, 0xbe, 0x46, 0x56, 0xed, 0xf0, 0x22,
0x48, 0xf2, 0x14, 0xd6, 0xf4, 0xe3, 0x95, 0xeb,
0x61, 0xea, 0x39, 0x16, 0x3c, 0xfa, 0x52, 0xaf,
0xd0, 0x05, 0x7f, 0xc7, 0x6f, 0x3e, 0x87, 0xf8,
0xae, 0xa9, 0xd3, 0x3a, 0x42, 0x9a, 0x6a, 0xc3,
0xf5, 0xab, 0x11, 0xbb, 0xb6, 0xb3, 0x00, 0xf3,
0x84, 0x38, 0x94, 0x4b, 0x80, 0x85, 0x9e, 0x64,
0x82, 0x7e, 0x5b, 0x0d, 0x99, 0xf6, 0xd8, 0xdb,
0x77, 0x44, 0xdf, 0x4e, 0x53, 0x58, 0xc9, 0x63,
0x7a, 0x0b, 0x5c, 0x20, 0x88, 0x72, 0x34, 0x0a,
0x8a, 0x1e, 0x30, 0xb7, 0x9c, 0x23, 0x3d, 0x1a,
0x8f, 0x4a, 0xfb, 0x5e, 0x81, 0xa2, 0x3f, 0x98,
0xaa, 0x07, 0x73, 0xa7, 0xf1, 0xce, 0x03, 0x96,
0x37, 0x3b, 0x97, 0xdc, 0x5a, 0x35, 0x17, 0x83,
0x7d, 0xad, 0x0f, 0xee, 0x4f, 0x5f, 0x59, 0x10,
0x69, 0x89, 0xe1, 0xe0, 0xd9, 0xa0, 0x25, 0x7b,
0x76, 0x49, 0x02, 0x9d, 0x2e, 0x74, 0x09, 0x91,
0x86, 0xe4, 0xcf, 0xd4, 0xca, 0xd7, 0x45, 0xe5,
0x1b, 0xbc, 0x43, 0x7c, 0xa8, 0xfc, 0x2a, 0x04,
0x1d, 0x6c, 0x15, 0xf7, 0x13, 0xcd, 0x27, 0xcb,
0xe9, 0x28, 0xba, 0x93, 0xc6, 0xc0, 0x9b, 0x21,
0xa4, 0xbf, 0x62, 0xcc, 0xa5, 0xb4, 0x75, 0x4c,
0x8c, 0x24, 0xd2, 0xac, 0x29, 0x36, 0x9f, 0x08,
0xb9, 0xe8, 0x71, 0xc4, 0xe7, 0x2f, 0x92, 0x78,
0x33, 0x41, 0x1c, 0x90, 0xfe, 0xdd, 0x5d, 0xbd,
0xc2, 0x8b, 0x70, 0x2b, 0x47, 0x6d, 0xb8, 0xd1,
};
uint8_t
pearson_hash(const void *data, size_t len)
{
const uint8_t *p;
uint8_t h;
for (p = data, h = 0; len > 0; ++p, --len)
h = T[h ^ *p];
return (h);
}
uint8_t
pearson_hash_str(const char *str)
{
uint8_t h;
for (h = 0; *str != '\0'; ++str)
h = T[h ^ (uint8_t)*str];
return (h);
}