projects / mirror_zfs.git / blame
| Commit | Line | Data |
|---|---|---|
| 37fb3e43 PD |
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 | ||
| 3f387973 | 25 | #include <cityhash.h> |
| 37fb3e43 PD |
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 | |
| 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 | |
| 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 | uint64_t | |
| 53 | cityhash4(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 | } | |
| 3f387973 MA |
64 | |
| 65 | #if defined(_KERNEL) | |
| 66 | EXPORT_SYMBOL(cityhash4); | |
| 67 | #endif |