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 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 } 64 65 #if defined(_KERNEL) 66 EXPORT_SYMBOL(cityhash4); 67 #endif 68