1 // SPDX-License-Identifier: MIT 2 // 3 // Copyright (c) 2011 Google, Inc. 4 // 5 // Permission is hereby granted, free of charge, to any person obtaining a copy 6 // of this software and associated documentation files (the "Software"), to deal 7 // in the Software without restriction, including without limitation the rights 8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9 // copies of the Software, and to permit persons to whom the Software is 10 // furnished to do so, subject to the following conditions: 11 // 12 // The above copyright notice and this permission notice shall be included in 13 // all copies or substantial portions of the Software. 14 // 15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 21 // THE SOFTWARE. 22 23 /* 24 * Copyright (c) 2017 by Delphix. All rights reserved. 25 */ 26 27 #include <cityhash.h> 28 29 #define HASH_K1 0xb492b66fbe98f273ULL 30 #define HASH_K2 0x9ae16a3b2f90404fULL 31 32 /* 33 * Bitwise right rotate. Normally this will compile to a single 34 * instruction. 35 */ 36 static inline uint64_t 37 rotate(uint64_t val, int shift) 38 { 39 // Avoid shifting by 64: doing so yields an undefined result. 40 return (shift == 0 ? val : (val >> shift) | (val << (64 - shift))); 41 } 42 43 static inline uint64_t 44 cityhash_helper(uint64_t u, uint64_t v, uint64_t mul) 45 { 46 uint64_t a = (u ^ v) * mul; 47 a ^= (a >> 47); 48 uint64_t b = (v ^ a) * mul; 49 b ^= (b >> 47); 50 b *= mul; 51 return (b); 52 } 53 54 static inline uint64_t 55 cityhash_impl(uint64_t w1, uint64_t w2, uint64_t w3, uint64_t w4) 56 { 57 uint64_t mul = HASH_K2 + 64; 58 uint64_t a = w1 * HASH_K1; 59 uint64_t b = w2; 60 uint64_t c = w4 * mul; 61 uint64_t d = w3 * HASH_K2; 62 return (cityhash_helper(rotate(a + b, 43) + rotate(c, 30) + d, 63 a + rotate(b + HASH_K2, 18) + c, mul)); 64 } 65 66 /* 67 * Passing w as the 2nd argument could save one 64-bit multiplication. 68 */ 69 uint64_t 70 cityhash1(uint64_t w) 71 { 72 return (cityhash_impl(0, w, 0, 0)); 73 } 74 75 uint64_t 76 cityhash2(uint64_t w1, uint64_t w2) 77 { 78 return (cityhash_impl(w1, w2, 0, 0)); 79 } 80 81 uint64_t 82 cityhash3(uint64_t w1, uint64_t w2, uint64_t w3) 83 { 84 return (cityhash_impl(w1, w2, w3, 0)); 85 } 86 87 uint64_t 88 cityhash4(uint64_t w1, uint64_t w2, uint64_t w3, uint64_t w4) 89 { 90 return (cityhash_impl(w1, w2, w3, w4)); 91 } 92 93 #if defined(_KERNEL) 94 EXPORT_SYMBOL(cityhash1); 95 EXPORT_SYMBOL(cityhash2); 96 EXPORT_SYMBOL(cityhash3); 97 EXPORT_SYMBOL(cityhash4); 98 #endif 99