2 * Copyright 2006 Bob Jenkins
4 * Derived from public domain source, see
5 * <http://burtleburtle.net/bob/c/lookup3.c>:
7 * "lookup3.c, by Bob Jenkins, May 2006, Public Domain.
9 * These are functions for producing 32-bit hashes for hash table lookup...
10 * ...You can use this free for any purpose. It's in the public domain.
11 * It has no warranty."
13 * Copyright (c) 2014-2016 Solarflare Communications Inc.
14 * All rights reserved.
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions are met:
19 * 1. Redistributions of source code must retain the above copyright notice,
20 * this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright notice,
22 * this list of conditions and the following disclaimer in the documentation
23 * and/or other materials provided with the distribution.
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
26 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
27 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
29 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
30 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
31 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
32 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
33 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
34 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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45 /* Hash initial value */
46 #define EFX_HASH_INITIAL_VALUE 0xdeadbeef
49 * Rotate a 32-bit value left
51 * Allow platform to provide an intrinsic or optimised routine and
52 * fall-back to a simple shift based implementation.
54 #if EFSYS_HAS_ROTL_DWORD
56 #define EFX_HASH_ROTATE(_value, _shift) \
57 EFSYS_ROTL_DWORD(_value, _shift)
61 #define EFX_HASH_ROTATE(_value, _shift) \
62 (((_value) << (_shift)) | ((_value) >> (32 - (_shift))))
66 /* Mix three 32-bit values reversibly */
67 #define EFX_HASH_MIX(_a, _b, _c) \
70 _a ^= EFX_HASH_ROTATE(_c, 4); \
73 _b ^= EFX_HASH_ROTATE(_a, 6); \
76 _c ^= EFX_HASH_ROTATE(_b, 8); \
79 _a ^= EFX_HASH_ROTATE(_c, 16); \
82 _b ^= EFX_HASH_ROTATE(_a, 19); \
85 _c ^= EFX_HASH_ROTATE(_b, 4); \
87 _NOTE(CONSTANTCONDITION) \
90 /* Final mixing of three 32-bit values into one (_c) */
91 #define EFX_HASH_FINALISE(_a, _b, _c) \
94 _c -= EFX_HASH_ROTATE(_b, 14); \
96 _a -= EFX_HASH_ROTATE(_c, 11); \
98 _b -= EFX_HASH_ROTATE(_a, 25); \
100 _c -= EFX_HASH_ROTATE(_b, 16); \
102 _a -= EFX_HASH_ROTATE(_c, 4); \
104 _b -= EFX_HASH_ROTATE(_a, 14); \
106 _c -= EFX_HASH_ROTATE(_b, 24); \
107 _NOTE(CONSTANTCONDITION) \
111 /* Produce a 32-bit hash from 32-bit aligned input */
112 __checkReturn uint32_t
114 __in_ecount(count) uint32_t const *input,
122 /* Set up the initial internal state */
123 a = b = c = EFX_HASH_INITIAL_VALUE +
124 (((uint32_t)count) * sizeof (uint32_t)) + init;
126 /* Handle all but the last three dwords of the input */
131 EFX_HASH_MIX(a, b, c);
137 /* Handle the left-overs */
147 EFX_HASH_FINALISE(a, b, c);
151 /* Should only get here if count parameter was zero */
158 #if EFSYS_IS_BIG_ENDIAN
160 /* Produce a 32-bit hash from arbitrarily aligned input */
161 __checkReturn uint32_t
163 __in_ecount(length) uint8_t const *input,
171 /* Set up the initial internal state */
172 a = b = c = EFX_HASH_INITIAL_VALUE + (uint32_t)length + init;
174 /* Handle all but the last twelve bytes of the input */
175 while (length > 12) {
176 a += ((uint32_t)input[0]) << 24;
177 a += ((uint32_t)input[1]) << 16;
178 a += ((uint32_t)input[2]) << 8;
179 a += ((uint32_t)input[3]);
180 b += ((uint32_t)input[4]) << 24;
181 b += ((uint32_t)input[5]) << 16;
182 b += ((uint32_t)input[6]) << 8;
183 b += ((uint32_t)input[7]);
184 c += ((uint32_t)input[8]) << 24;
185 c += ((uint32_t)input[9]) << 16;
186 c += ((uint32_t)input[10]) << 8;
187 c += ((uint32_t)input[11]);
188 EFX_HASH_MIX(a, b, c);
193 /* Handle the left-overs */
196 c += ((uint32_t)input[11]);
199 c += ((uint32_t)input[10]) << 8;
202 c += ((uint32_t)input[9]) << 16;
205 c += ((uint32_t)input[8]) << 24;
208 b += ((uint32_t)input[7]);
211 b += ((uint32_t)input[6]) << 8;
214 b += ((uint32_t)input[5]) << 16;
217 b += ((uint32_t)input[4]) << 24;
220 a += ((uint32_t)input[3]);
223 a += ((uint32_t)input[2]) << 8;
226 a += ((uint32_t)input[1]) << 16;
229 a += ((uint32_t)input[0]) << 24;
230 EFX_HASH_FINALISE(a, b, c);
234 /* Should only get here if length parameter was zero */
241 #elif EFSYS_IS_LITTLE_ENDIAN
243 /* Produce a 32-bit hash from arbitrarily aligned input */
244 __checkReturn uint32_t
246 __in_ecount(length) uint8_t const *input,
254 /* Set up the initial internal state */
255 a = b = c = EFX_HASH_INITIAL_VALUE + (uint32_t)length + init;
257 /* Handle all but the last twelve bytes of the input */
258 while (length > 12) {
259 a += ((uint32_t)input[0]);
260 a += ((uint32_t)input[1]) << 8;
261 a += ((uint32_t)input[2]) << 16;
262 a += ((uint32_t)input[3]) << 24;
263 b += ((uint32_t)input[4]);
264 b += ((uint32_t)input[5]) << 8;
265 b += ((uint32_t)input[6]) << 16;
266 b += ((uint32_t)input[7]) << 24;
267 c += ((uint32_t)input[8]);
268 c += ((uint32_t)input[9]) << 8;
269 c += ((uint32_t)input[10]) << 16;
270 c += ((uint32_t)input[11]) << 24;
271 EFX_HASH_MIX(a, b, c);
276 /* Handle the left-overs */
279 c += ((uint32_t)input[11]) << 24;
282 c += ((uint32_t)input[10]) << 16;
285 c += ((uint32_t)input[9]) << 8;
288 c += ((uint32_t)input[8]);
291 b += ((uint32_t)input[7]) << 24;
294 b += ((uint32_t)input[6]) << 16;
297 b += ((uint32_t)input[5]) << 8;
300 b += ((uint32_t)input[4]);
303 a += ((uint32_t)input[3]) << 24;
306 a += ((uint32_t)input[2]) << 16;
309 a += ((uint32_t)input[1]) << 8;
312 a += ((uint32_t)input[0]);
313 EFX_HASH_FINALISE(a, b, c);
317 /* Should only get here if length parameter was zero */
326 #error "Neither of EFSYS_IS_{BIG,LITTLE}_ENDIAN is set"