Differential D461 Diff 1949 sys/libkern/murmur3_32.c

Changeset View

Standalone View

sys/libkern/murmur3_32.c

This file was added.

Property	Old Value	New Value
svn:eol-style	null	native \ No newline at end of property
svn:keywords	null	FreeBSD=%H \ No newline at end of property
svn:mime-type	null	text/plain \ No newline at end of property

				/*-
				* 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.
				*/

				#include <sys/hash.h>
				#include <sys/endian.h>
				#include <sys/stdint.h>
				#include <sys/types.h>

				desUnsubmitted Not Done Inline Actions <sys/types.h> should always come first, and <sys/stdint.h> is redundant. des: <sys/types.h> should always come first, and <sys/stdint.h> is redundant.
				#define rol32(i32, n) ((i32) << (n) \| (i32) >> (32 - (n)))

				/*
				* Simple implementation of the Murmur3-32 hash function optimized for
				* aligned sequences of 32-bit words. If len is not a multiple of 4, it
				* will be rounded down, droping trailer bytes.
				*/
				emasteUnsubmitted Not Done Inline Actions Should we have a different name for this function, due to the multiple-of-4 issue? (I.e., other implementations called murmur3_32 handle the 0-3 byte tail.) emaste: Should we have a different name for this function, due to the multiple-of-4 issue? (I.e.
				uint32_t
				murmur3_aligned_32(const void *data, size_t len, uint32_t seed)
				{
				const uint32_t *data32;
				uint32_t hash, k;
				size_t res;

				/* initialize */
				len -= len % sizeof(*data32);
				res = len;
				data32 = data;
				hash = seed;

				/* iterate */
				for (res = 0; res < len; res += sizeof(*data32), data32++) {
				k = le32toh(*data32);
				k *= 0xcc9e2d51;
				k = rol32(k, 15);
				k *= 0x1b873593;
				hash ^= k;
				hash = rol32(hash, 13);
				hash *= 5;
				hash += 0xe6546b64;
				}

				/* finalize */
				hash ^= (uint32_t)len;
				hash ^= hash >> 16;
				hash *= 0x85ebca6b;
				hash ^= hash >> 13;
				hash *= 0xc2b2ae35;
				hash ^= hash >> 16;
				return (hash);
				}

				desUnsubmitted Not Done Inline Actions <string.h> isn't needed. des: <string.h> isn't needed.