1*3a2d8a1bSPaul Dagnelie // Copyright (c) 2011 Google, Inc.
2*3a2d8a1bSPaul Dagnelie //
3*3a2d8a1bSPaul Dagnelie // Permission is hereby granted, free of charge, to any person obtaining a copy
4*3a2d8a1bSPaul Dagnelie // of this software and associated documentation files (the "Software"), to deal
5*3a2d8a1bSPaul Dagnelie // in the Software without restriction, including without limitation the rights
6*3a2d8a1bSPaul Dagnelie // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
7*3a2d8a1bSPaul Dagnelie // copies of the Software, and to permit persons to whom the Software is
8*3a2d8a1bSPaul Dagnelie // furnished to do so, subject to the following conditions:
9*3a2d8a1bSPaul Dagnelie //
10*3a2d8a1bSPaul Dagnelie // The above copyright notice and this permission notice shall be included in
11*3a2d8a1bSPaul Dagnelie // all copies or substantial portions of the Software.
12*3a2d8a1bSPaul Dagnelie //
13*3a2d8a1bSPaul Dagnelie // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14*3a2d8a1bSPaul Dagnelie // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15*3a2d8a1bSPaul Dagnelie // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16*3a2d8a1bSPaul Dagnelie // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17*3a2d8a1bSPaul Dagnelie // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
18*3a2d8a1bSPaul Dagnelie // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
19*3a2d8a1bSPaul Dagnelie // THE SOFTWARE.
20*3a2d8a1bSPaul Dagnelie
21*3a2d8a1bSPaul Dagnelie /*
22*3a2d8a1bSPaul Dagnelie * Copyright (c) 2017 by Delphix. All rights reserved.
23*3a2d8a1bSPaul Dagnelie */
24*3a2d8a1bSPaul Dagnelie
25*3a2d8a1bSPaul Dagnelie #include <sys/cityhash.h>
26*3a2d8a1bSPaul Dagnelie
27*3a2d8a1bSPaul Dagnelie #define HASH_K1 0xb492b66fbe98f273ULL
28*3a2d8a1bSPaul Dagnelie #define HASH_K2 0x9ae16a3b2f90404fULL
29*3a2d8a1bSPaul Dagnelie
30*3a2d8a1bSPaul Dagnelie /*
31*3a2d8a1bSPaul Dagnelie * Bitwise right rotate. Normally this will compile to a single
32*3a2d8a1bSPaul Dagnelie * instruction.
33*3a2d8a1bSPaul Dagnelie */
34*3a2d8a1bSPaul Dagnelie static inline uint64_t
rotate(uint64_t val,int shift)35*3a2d8a1bSPaul Dagnelie rotate(uint64_t val, int shift)
36*3a2d8a1bSPaul Dagnelie {
37*3a2d8a1bSPaul Dagnelie // Avoid shifting by 64: doing so yields an undefined result.
38*3a2d8a1bSPaul Dagnelie return (shift == 0 ? val : (val >> shift) | (val << (64 - shift)));
39*3a2d8a1bSPaul Dagnelie }
40*3a2d8a1bSPaul Dagnelie
41*3a2d8a1bSPaul Dagnelie static inline uint64_t
cityhash_helper(uint64_t u,uint64_t v,uint64_t mul)42*3a2d8a1bSPaul Dagnelie cityhash_helper(uint64_t u, uint64_t v, uint64_t mul)
43*3a2d8a1bSPaul Dagnelie {
44*3a2d8a1bSPaul Dagnelie uint64_t a = (u ^ v) * mul;
45*3a2d8a1bSPaul Dagnelie a ^= (a >> 47);
46*3a2d8a1bSPaul Dagnelie uint64_t b = (v ^ a) * mul;
47*3a2d8a1bSPaul Dagnelie b ^= (b >> 47);
48*3a2d8a1bSPaul Dagnelie b *= mul;
49*3a2d8a1bSPaul Dagnelie return (b);
50*3a2d8a1bSPaul Dagnelie }
51*3a2d8a1bSPaul Dagnelie
52*3a2d8a1bSPaul Dagnelie uint64_t
cityhash4(uint64_t w1,uint64_t w2,uint64_t w3,uint64_t w4)53*3a2d8a1bSPaul Dagnelie cityhash4(uint64_t w1, uint64_t w2, uint64_t w3, uint64_t w4)
54*3a2d8a1bSPaul Dagnelie {
55*3a2d8a1bSPaul Dagnelie uint64_t mul = HASH_K2 + 64;
56*3a2d8a1bSPaul Dagnelie uint64_t a = w1 * HASH_K1;
57*3a2d8a1bSPaul Dagnelie uint64_t b = w2;
58*3a2d8a1bSPaul Dagnelie uint64_t c = w4 * mul;
59*3a2d8a1bSPaul Dagnelie uint64_t d = w3 * HASH_K2;
60*3a2d8a1bSPaul Dagnelie return (cityhash_helper(rotate(a + b, 43) + rotate(c, 30) + d,
61*3a2d8a1bSPaul Dagnelie a + rotate(b + HASH_K2, 18) + c, mul));
62*3a2d8a1bSPaul Dagnelie
63*3a2d8a1bSPaul Dagnelie }
64