1 // SPDX-License-Identifier: MIT
2 //
3 // Copyright (c) 2011 Google, Inc.
4 //
5 // Permission is hereby granted, free of charge, to any person obtaining a copy
6 // of this software and associated documentation files (the "Software"), to deal
7 // in the Software without restriction, including without limitation the rights
8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 // copies of the Software, and to permit persons to whom the Software is
10 // furnished to do so, subject to the following conditions:
11 //
12 // The above copyright notice and this permission notice shall be included in
13 // all copies or substantial portions of the Software.
14 //
15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
21 // THE SOFTWARE.
22
23 /*
24 * Copyright (c) 2017 by Delphix. All rights reserved.
25 */
26
27 #include <cityhash.h>
28
29 #define HASH_K1 0xb492b66fbe98f273ULL
30 #define HASH_K2 0x9ae16a3b2f90404fULL
31
32 /*
33 * Bitwise right rotate. Normally this will compile to a single
34 * instruction.
35 */
36 static inline uint64_t
rotate(uint64_t val,int shift)37 rotate(uint64_t val, int shift)
38 {
39 // Avoid shifting by 64: doing so yields an undefined result.
40 return (shift == 0 ? val : (val >> shift) | (val << (64 - shift)));
41 }
42
43 static inline uint64_t
cityhash_helper(uint64_t u,uint64_t v,uint64_t mul)44 cityhash_helper(uint64_t u, uint64_t v, uint64_t mul)
45 {
46 uint64_t a = (u ^ v) * mul;
47 a ^= (a >> 47);
48 uint64_t b = (v ^ a) * mul;
49 b ^= (b >> 47);
50 b *= mul;
51 return (b);
52 }
53
54 static inline uint64_t
cityhash_impl(uint64_t w1,uint64_t w2,uint64_t w3,uint64_t w4)55 cityhash_impl(uint64_t w1, uint64_t w2, uint64_t w3, uint64_t w4)
56 {
57 uint64_t mul = HASH_K2 + 64;
58 uint64_t a = w1 * HASH_K1;
59 uint64_t b = w2;
60 uint64_t c = w4 * mul;
61 uint64_t d = w3 * HASH_K2;
62 return (cityhash_helper(rotate(a + b, 43) + rotate(c, 30) + d,
63 a + rotate(b + HASH_K2, 18) + c, mul));
64 }
65
66 /*
67 * Passing w as the 2nd argument could save one 64-bit multiplication.
68 */
69 uint64_t
cityhash1(uint64_t w)70 cityhash1(uint64_t w)
71 {
72 return (cityhash_impl(0, w, 0, 0));
73 }
74
75 uint64_t
cityhash2(uint64_t w1,uint64_t w2)76 cityhash2(uint64_t w1, uint64_t w2)
77 {
78 return (cityhash_impl(w1, w2, 0, 0));
79 }
80
81 uint64_t
cityhash3(uint64_t w1,uint64_t w2,uint64_t w3)82 cityhash3(uint64_t w1, uint64_t w2, uint64_t w3)
83 {
84 return (cityhash_impl(w1, w2, w3, 0));
85 }
86
87 uint64_t
cityhash4(uint64_t w1,uint64_t w2,uint64_t w3,uint64_t w4)88 cityhash4(uint64_t w1, uint64_t w2, uint64_t w3, uint64_t w4)
89 {
90 return (cityhash_impl(w1, w2, w3, w4));
91 }
92
93 #if defined(_KERNEL)
94 EXPORT_SYMBOL(cityhash1);
95 EXPORT_SYMBOL(cityhash2);
96 EXPORT_SYMBOL(cityhash3);
97 EXPORT_SYMBOL(cityhash4);
98 #endif
99