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Diffstat (limited to 'storage/innobase/include/ut0rnd.inl')
| -rw-r--r-- | storage/innobase/include/ut0rnd.inl | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/storage/innobase/include/ut0rnd.inl b/storage/innobase/include/ut0rnd.inl new file mode 100644 index 00000000..37da323f --- /dev/null +++ b/storage/innobase/include/ut0rnd.inl @@ -0,0 +1,128 @@ +/***************************************************************************** + +Copyright (c) 1994, 2016, Oracle and/or its affiliates. All Rights Reserved. +Copyright (c) 2017, 2021, MariaDB Corporation. + +This program is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free Software +Foundation; version 2 of the License. + +This program is distributed in the hope that it will be useful, but WITHOUT +ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS +FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. + +You should have received a copy of the GNU General Public License along with +this program; if not, write to the Free Software Foundation, Inc., +51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA + +*****************************************************************************/ + +/**************************************************************//** +@file include/ut0rnd.ic +Random numbers and hashing + +Created 5/30/1994 Heikki Tuuri +*******************************************************************/ + +#define UT_HASH_RANDOM_MASK 1463735687 +#define UT_HASH_RANDOM_MASK2 1653893711 + +#ifndef UNIV_INNOCHECKSUM + +/*******************************************************//** +The following function generates a hash value for a ulint integer +to a hash table of size table_size, which should be a prime +or some random number for the hash table to work reliably. +@return hash value */ +UNIV_INLINE +ulint +ut_hash_ulint( +/*==========*/ + ulint key, /*!< in: value to be hashed */ + ulint table_size) /*!< in: hash table size */ +{ + ut_ad(table_size); + key = key ^ UT_HASH_RANDOM_MASK2; + + return(key % table_size); +} + +/*************************************************************//** +Folds a 64-bit integer. +@return folded value */ +UNIV_INLINE +ulint +ut_fold_ull( +/*========*/ + ib_uint64_t d) /*!< in: 64-bit integer */ +{ + return(ut_fold_ulint_pair((ulint) d & ULINT32_MASK, + (ulint) (d >> 32))); +} +#endif /* !UNIV_INNOCHECKSUM */ + +/*************************************************************//** +Folds a pair of ulints. +@return folded value */ +UNIV_INLINE +ulint +ut_fold_ulint_pair( +/*===============*/ + ulint n1, /*!< in: ulint */ + ulint n2) /*!< in: ulint */ +{ + return(((((n1 ^ n2 ^ UT_HASH_RANDOM_MASK2) << 8) + n1) + ^ UT_HASH_RANDOM_MASK) + n2); +} + +/*************************************************************//** +Folds a binary string. +@return folded value */ +UNIV_INLINE +ulint +ut_fold_binary( +/*===========*/ + const byte* str, /*!< in: string of bytes */ + ulint len) /*!< in: length */ +{ + ulint fold = 0; + const byte* str_end = str + (len & 0xFFFFFFF8); + + ut_ad(str || !len); + + while (str < str_end) { + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + } + + switch (len & 0x7) { + case 7: + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + /* fall through */ + case 6: + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + /* fall through */ + case 5: + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + /* fall through */ + case 4: + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + /* fall through */ + case 3: + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + /* fall through */ + case 2: + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + /* fall through */ + case 1: + fold = ut_fold_ulint_pair(fold, (ulint)(*str++)); + } + + return(fold); +} |