1/***************************************************************************** 2 3Copyright (c) 1994, 2018, Oracle and/or its affiliates. All Rights Reserved. 4 5This program is free software; you can redistribute it and/or modify it under 6the terms of the GNU General Public License, version 2.0, as published by the 7Free Software Foundation. 8 9This program is also distributed with certain software (including but not 10limited to OpenSSL) that is licensed under separate terms, as designated in a 11particular file or component or in included license documentation. The authors 12of MySQL hereby grant you an additional permission to link the program and 13your derivative works with the separately licensed software that they have 14included with MySQL. 15 16This program is distributed in the hope that it will be useful, but WITHOUT 17ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 18FOR A PARTICULAR PURPOSE. See the GNU General Public License, version 2.0, 19for more details. 20 21You should have received a copy of the GNU General Public License along with 22this program; if not, write to the Free Software Foundation, Inc., 2351 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 24 25*****************************************************************************/ 26 27/** @file include/ut0rnd.ic 28 Random numbers and hashing 29 30 Created 5/30/1994 Heikki Tuuri 31 *******************************************************************/ 32 33#define UT_HASH_RANDOM_MASK 1463735687 34#define UT_HASH_RANDOM_MASK2 1653893711 35 36#define UT_RND1 151117737 37#define UT_RND2 119785373 38#define UT_RND3 85689495 39#define UT_RND4 76595339 40#define UT_SUM_RND2 98781234 41#define UT_SUM_RND3 126792457 42#define UT_SUM_RND4 63498502 43#define UT_XOR_RND1 187678878 44#define UT_XOR_RND2 143537923 45 46#include <my_thread_local.h> 47 48/** Seed value of ut_rnd_gen_ulint() */ 49extern thread_local ulint ut_rnd_ulint_counter; 50 51/** The following function generates a series of 'random' ulint integers. 52 This function is now based on thread local variables. 53 @return the next 'random' number */ 54UNIV_INLINE 55ulint ut_rnd_gen_next_ulint( 56 ulint rnd) /*!< in: the previous random number value */ 57{ 58 ulint n_bits; 59 60 n_bits = 8 * sizeof(ulint); 61 62 rnd = UT_RND2 * rnd + UT_SUM_RND3; 63 rnd = UT_XOR_RND1 ^ rnd; 64 rnd = (rnd << 20) + (rnd >> (n_bits - 20)); 65 rnd = UT_RND3 * rnd + UT_SUM_RND4; 66 rnd = UT_XOR_RND2 ^ rnd; 67 rnd = (rnd << 20) + (rnd >> (n_bits - 20)); 68 rnd = UT_RND1 * rnd + UT_SUM_RND2; 69 70 return (rnd); 71} 72 73/** The following function generates 'random' ulint integers which 74enumerate the value space of ulint integers in a pseudo random 75fashion. Note that the same integer is repeated always after 762 to power 32 calls to the generator (if ulint is 32-bit). 77@return pseudo random number */ 78ulint ut_rnd_gen_ulint() { 79 ulint rnd = ut_rnd_ulint_counter; 80 if (rnd == 0) { 81 rnd = 65654363; 82 } 83 84 rnd = UT_RND1 * rnd + UT_RND2; 85 86 ut_rnd_ulint_counter = rnd; 87 88 return (ut_rnd_gen_next_ulint(rnd)); 89} 90 91/** Generates a random integer from a given interval. 92 This function is now based on thread local variables. 93 @return the 'random' number */ 94UNIV_INLINE 95ulint ut_rnd_interval( 96 ulint low, /*!< in: low limit; can generate also this value */ 97 ulint high) /*!< in: high limit; can generate also this value */ 98{ 99 ulint rnd; 100 101 ut_ad(high >= low); 102 103 if (low == high) { 104 return (low); 105 } 106 107 rnd = ut_rnd_gen_ulint(); 108 109 return (low + (rnd % (high - low))); 110} 111 112/** The following function generates a hash value for a ulint integer 113 to a hash table of size table_size, which should be a prime 114 or some random number for the hash table to work reliably. 115 @return hash value */ 116UNIV_INLINE 117ulint ut_hash_ulint(ulint key, /*!< in: value to be hashed */ 118 ulint table_size) /*!< in: hash table size */ 119{ 120 ut_ad(table_size); 121 key = key ^ UT_HASH_RANDOM_MASK2; 122 123 return (key % table_size); 124} 125 126/** Folds a 64-bit integer. 127 @return folded value */ 128UNIV_INLINE 129ulint ut_fold_ull(ib_uint64_t d) /*!< in: 64-bit integer */ 130{ 131 return (ut_fold_ulint_pair((ulint)d & ULINT32_MASK, (ulint)(d >> 32))); 132} 133 134/** Folds a character string ending in the null character. 135 @return folded value */ 136UNIV_INLINE 137ulint ut_fold_string(const char *str) /*!< in: null-terminated string */ 138{ 139 ulint fold = 0; 140 141 ut_ad(str); 142 143 while (*str != '\0') { 144 fold = ut_fold_ulint_pair(fold, (ulint)(*str)); 145 str++; 146 } 147 148 return (fold); 149} 150 151/** Folds a pair of ulints. 152 @return folded value */ 153UNIV_INLINE 154ulint ut_fold_ulint_pair(ulint n1, /*!< in: ulint */ 155 ulint n2) /*!< in: ulint */ 156{ 157 return ( 158 ((((n1 ^ n2 ^ UT_HASH_RANDOM_MASK2) << 8) + n1) ^ UT_HASH_RANDOM_MASK) + 159 n2); 160} 161 162/** Folds a binary string. 163 @return folded value */ 164UNIV_INLINE 165ulint ut_fold_binary(const byte *str, /*!< in: string of bytes */ 166 ulint len) /*!< in: length */ 167{ 168 ulint fold = 0; 169 const byte *str_end = str + (len & 0xFFFFFFF8); 170 171 ut_ad(str || !len); 172 173 while (str < str_end) { 174 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 175 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 176 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 177 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 178 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 179 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 180 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 181 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 182 } 183 184 switch (len & 0x7) { 185 case 7: 186 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 187 // Fall through. 188 case 6: 189 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 190 // Fall through. 191 case 5: 192 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 193 // Fall through. 194 case 4: 195 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 196 // Fall through. 197 case 3: 198 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 199 // Fall through. 200 case 2: 201 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 202 // Fall through. 203 case 1: 204 fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); 205 } 206 207 return (fold); 208} 209