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- /*-
- * 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);
- }
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