| // Copyright (c) 2011 Google, Inc. |
| // |
| // Permission is hereby granted, free of charge, to any person obtaining a copy |
| // of this software and associated documentation files (the "Software"), to deal |
| // in the Software without restriction, including without limitation the rights |
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| // copies of the Software, and to permit persons to whom the Software is |
| // furnished to do so, subject to the following conditions: |
| // |
| // The above copyright notice and this permission notice shall be included in |
| // all copies or substantial portions of the Software. |
| // |
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| // THE SOFTWARE. |
| |
| /* |
| * Copyright (c) 2017 by Delphix. All rights reserved. |
| */ |
| |
| #include <sys/cityhash.h> |
| |
| #define HASH_K1 0xb492b66fbe98f273ULL |
| #define HASH_K2 0x9ae16a3b2f90404fULL |
| |
| /* |
| * Bitwise right rotate. Normally this will compile to a single |
| * instruction. |
| */ |
| static inline uint64_t |
| rotate(uint64_t val, int shift) |
| { |
| // Avoid shifting by 64: doing so yields an undefined result. |
| return (shift == 0 ? val : (val >> shift) | (val << (64 - shift))); |
| } |
| |
| static inline uint64_t |
| cityhash_helper(uint64_t u, uint64_t v, uint64_t mul) |
| { |
| uint64_t a = (u ^ v) * mul; |
| a ^= (a >> 47); |
| uint64_t b = (v ^ a) * mul; |
| b ^= (b >> 47); |
| b *= mul; |
| return (b); |
| } |
| |
| uint64_t |
| cityhash4(uint64_t w1, uint64_t w2, uint64_t w3, uint64_t w4) |
| { |
| uint64_t mul = HASH_K2 + 64; |
| uint64_t a = w1 * HASH_K1; |
| uint64_t b = w2; |
| uint64_t c = w4 * mul; |
| uint64_t d = w3 * HASH_K2; |
| return (cityhash_helper(rotate(a + b, 43) + rotate(c, 30) + d, |
| a + rotate(b + HASH_K2, 18) + c, mul)); |
| |
| } |