99e9de871a
so they match the established idiom. Document them in hash(9). MFC after: 1 month MFC with: r272906
133 lines
3.4 KiB
C
133 lines
3.4 KiB
C
/*-
|
|
* Copyright (c) 2014 Dag-Erling Smørgrav
|
|
* 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.
|
|
*
|
|
* 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.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
#include <sys/hash.h>
|
|
#include <sys/endian.h>
|
|
#include <sys/stdint.h>
|
|
#include <sys/types.h>
|
|
|
|
#define rol32(i32, n) ((i32) << (n) | (i32) >> (32 - (n)))
|
|
|
|
/*
|
|
* Simple implementation of the Murmur3-32 hash function.
|
|
*
|
|
* This implementation is slow but safe. It can be made significantly
|
|
* faster if the caller guarantees that the input is correctly aligned for
|
|
* 32-bit reads, and slightly faster yet if the caller guarantees that the
|
|
* length of the input is always a multiple of 4 bytes.
|
|
*/
|
|
uint32_t
|
|
murmur3_32_hash(const void *data, size_t len, uint32_t seed)
|
|
{
|
|
const uint8_t *bytes;
|
|
uint32_t hash, k;
|
|
size_t res;
|
|
|
|
/* initialization */
|
|
bytes = data;
|
|
res = len;
|
|
hash = seed;
|
|
|
|
/* main loop */
|
|
while (res >= 4) {
|
|
/* replace with le32toh() if input is aligned */
|
|
k = le32dec(bytes);
|
|
bytes += 4;
|
|
res -= 4;
|
|
k *= 0xcc9e2d51;
|
|
k = rol32(k, 15);
|
|
k *= 0x1b873593;
|
|
hash ^= k;
|
|
hash = rol32(hash, 13);
|
|
hash *= 5;
|
|
hash += 0xe6546b64;
|
|
}
|
|
|
|
/* remainder */
|
|
/* remove if input length is a multiple of 4 */
|
|
if (res > 0) {
|
|
k = 0;
|
|
switch (res) {
|
|
case 3:
|
|
k |= bytes[2] << 16;
|
|
case 2:
|
|
k |= bytes[1] << 8;
|
|
case 1:
|
|
k |= bytes[0];
|
|
k *= 0xcc9e2d51;
|
|
k = rol32(k, 15);
|
|
k *= 0x1b873593;
|
|
hash ^= k;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* finalize */
|
|
hash ^= (uint32_t)len;
|
|
hash ^= hash >> 16;
|
|
hash *= 0x85ebca6b;
|
|
hash ^= hash >> 13;
|
|
hash *= 0xc2b2ae35;
|
|
hash ^= hash >> 16;
|
|
return (hash);
|
|
}
|
|
|
|
/*
|
|
* Simplified version of the above optimized for aligned sequences of
|
|
* 32-bit words. The count argument is the number of words, not the
|
|
* length in bytes.
|
|
*/
|
|
uint32_t
|
|
murmur3_32_hash32(const uint32_t *data, size_t count, uint32_t seed)
|
|
{
|
|
uint32_t hash, k;
|
|
size_t res;
|
|
|
|
/* iterate */
|
|
for (res = count, hash = seed; res > 0; res--, data++) {
|
|
k = le32toh(*data);
|
|
k *= 0xcc9e2d51;
|
|
k = rol32(k, 15);
|
|
k *= 0x1b873593;
|
|
hash ^= k;
|
|
hash = rol32(hash, 13);
|
|
hash *= 5;
|
|
hash += 0xe6546b64;
|
|
}
|
|
|
|
/* finalize */
|
|
hash ^= (uint32_t)count;
|
|
hash ^= hash >> 16;
|
|
hash *= 0x85ebca6b;
|
|
hash ^= hash >> 13;
|
|
hash *= 0xc2b2ae35;
|
|
hash ^= hash >> 16;
|
|
return (hash);
|
|
}
|
|
|