| 1 | /* $NetBSD: mi_vector_hash.c,v 1.1 2013/12/11 01:24:08 joerg Exp $ */ |
| 2 | /*- |
| 3 | * Copyright (c) 2009 The NetBSD Foundation, Inc. |
| 4 | * All rights reserved. |
| 5 | * |
| 6 | * This code is derived from software contributed to The NetBSD Foundation |
| 7 | * by Joerg Sonnenberger. |
| 8 | * |
| 9 | * Redistribution and use in source and binary forms, with or without |
| 10 | * modification, are permitted provided that the following conditions |
| 11 | * are met: |
| 12 | * |
| 13 | * 1. Redistributions of source code must retain the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in |
| 17 | * the documentation and/or other materials provided with the |
| 18 | * distribution. |
| 19 | * |
| 20 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 21 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 22 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| 23 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| 24 | * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 25 | * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| 26 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 27 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| 28 | * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| 29 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| 30 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 31 | * SUCH DAMAGE. |
| 32 | */ |
| 33 | |
| 34 | /* |
| 35 | * See http://burtleburtle.net/bob/hash/doobs.html for the full description |
| 36 | * and the original version of the code. This version differs by exposing |
| 37 | * the full internal state and avoiding byte operations in the inner loop |
| 38 | * if the key is aligned correctly. |
| 39 | */ |
| 40 | |
| 41 | #if HAVE_NBTOOL_CONFIG_H |
| 42 | #include "nbtool_config.h" |
| 43 | #endif |
| 44 | |
| 45 | #include <sys/cdefs.h> |
| 46 | __RCSID("$NetBSD: mi_vector_hash.c,v 1.1 2013/12/11 01:24:08 joerg Exp $" ); |
| 47 | |
| 48 | #if !HAVE_NBTOOL_CONFIG_H || HAVE_SYS_ENDIAN_H |
| 49 | #include <sys/endian.h> |
| 50 | #endif |
| 51 | |
| 52 | #if defined(_KERNEL) || defined(_STANDALONE) |
| 53 | #include <sys/types.h> |
| 54 | #include <sys/systm.h> |
| 55 | #include <lib/libkern/libkern.h> |
| 56 | #else |
| 57 | #include "namespace.h" |
| 58 | |
| 59 | #include <stdint.h> |
| 60 | #include <stdlib.h> |
| 61 | #endif |
| 62 | |
| 63 | #define mix(a, b, c) do { \ |
| 64 | a -= b; a -= c; a ^= (c >> 13); \ |
| 65 | b -= c; b -= a; b ^= (a << 8); \ |
| 66 | c -= a; c -= b; c ^= (b >> 13); \ |
| 67 | a -= b; a -= c; a ^= (c >> 12); \ |
| 68 | b -= c; b -= a; b ^= (a << 16); \ |
| 69 | c -= a; c -= b; c ^= (b >> 5); \ |
| 70 | a -= b; a -= c; a ^= (c >> 3); \ |
| 71 | b -= c; b -= a; b ^= (a << 10); \ |
| 72 | c -= a; c -= b; c ^= (b >> 15); \ |
| 73 | } while (/* CONSTCOND */0) |
| 74 | |
| 75 | #define FIXED_SEED 0x9e3779b9 /* Golden ratio, arbitrary constant */ |
| 76 | |
| 77 | #if !defined(_KERNEL) && !defined(_STANDALONE) |
| 78 | #ifdef __weak_alias |
| 79 | __weak_alias(mi_vector_hash, _mi_vector_hash) |
| 80 | #endif |
| 81 | #endif |
| 82 | |
| 83 | void |
| 84 | mi_vector_hash(const void * __restrict key, size_t len, uint32_t seed, |
| 85 | uint32_t hashes[3]) |
| 86 | { |
| 87 | static const uint32_t mask[4] = { |
| 88 | 0x000000ff, 0x0000ffff, 0x00ffffff, 0xffffffff |
| 89 | }; |
| 90 | uint32_t orig_len, a, b, c; |
| 91 | const uint8_t *k; |
| 92 | |
| 93 | orig_len = (uint32_t)len; |
| 94 | |
| 95 | a = b = FIXED_SEED; |
| 96 | c = seed; |
| 97 | |
| 98 | if ((uintptr_t)key & 3) { |
| 99 | k = key; |
| 100 | while (len >= 12) { |
| 101 | a += le32dec(k); |
| 102 | b += le32dec(k + 4); |
| 103 | c += le32dec(k + 8); |
| 104 | mix(a, b, c); |
| 105 | k += 12; |
| 106 | len -= 12; |
| 107 | } |
| 108 | c += orig_len; |
| 109 | |
| 110 | if (len > 8) { |
| 111 | switch (len) { |
| 112 | case 11: |
| 113 | c += (uint32_t)k[10] << 24; |
| 114 | /* FALLTHROUGH */ |
| 115 | case 10: |
| 116 | c += (uint32_t)k[9] << 16; |
| 117 | /* FALLTHROUGH */ |
| 118 | case 9: |
| 119 | c += (uint32_t)k[8] << 8; |
| 120 | /* FALLTHROUGH */ |
| 121 | } |
| 122 | b += le32dec(k + 4); |
| 123 | a += le32dec(k); |
| 124 | } else if (len > 4) { |
| 125 | switch (len) { |
| 126 | case 8: |
| 127 | b += (uint32_t)k[7] << 24; |
| 128 | /* FALLTHROUGH */ |
| 129 | case 7: |
| 130 | b += (uint32_t)k[6] << 16; |
| 131 | /* FALLTHROUGH */ |
| 132 | case 6: |
| 133 | b += (uint32_t)k[5] << 8; |
| 134 | /* FALLTHROUGH */ |
| 135 | case 5: |
| 136 | b += k[4]; |
| 137 | /* FALLTHROUGH */ |
| 138 | } |
| 139 | a += le32dec(k); |
| 140 | } else if (len) { |
| 141 | switch (len) { |
| 142 | case 4: |
| 143 | a += (uint32_t)k[3] << 24; |
| 144 | /* FALLTHROUGH */ |
| 145 | case 3: |
| 146 | a += (uint32_t)k[2] << 16; |
| 147 | /* FALLTHROUGH */ |
| 148 | case 2: |
| 149 | a += (uint32_t)k[1] << 8; |
| 150 | /* FALLTHROUGH */ |
| 151 | case 1: |
| 152 | a += k[0]; |
| 153 | /* FALLTHROUGH */ |
| 154 | } |
| 155 | } |
| 156 | } else { |
| 157 | const uint32_t *key32 = key; |
| 158 | while (len >= 12) { |
| 159 | a += le32toh(key32[0]); |
| 160 | b += le32toh(key32[1]); |
| 161 | c += le32toh(key32[2]); |
| 162 | mix(a, b, c); |
| 163 | key32 += 3; |
| 164 | len -= 12; |
| 165 | } |
| 166 | c += orig_len; |
| 167 | |
| 168 | if (len > 8) { |
| 169 | c += (le32toh(key32[2]) & mask[len - 9]) << 8; |
| 170 | b += le32toh(key32[1]); |
| 171 | a += le32toh(key32[0]); |
| 172 | } else if (len > 4) { |
| 173 | b += le32toh(key32[1]) & mask[len - 5]; |
| 174 | a += le32toh(key32[0]); |
| 175 | } else if (len) |
| 176 | a += le32toh(key32[0]) & mask[len - 1]; |
| 177 | } |
| 178 | mix(a, b, c); |
| 179 | hashes[0] = a; |
| 180 | hashes[1] = b; |
| 181 | hashes[2] = c; |
| 182 | } |
| 183 | |