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