1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
|
/*****************************************************************************
Copyright (c) 1994, 2016, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2017, 2019, 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)));
}
/*************************************************************//**
Folds a character string ending in the null character.
@return folded value */
UNIV_INLINE
ulint
ut_fold_string(
/*===========*/
const char* str) /*!< in: null-terminated string */
{
ulint fold = 0;
ut_ad(str);
while (*str != '\0') {
fold = ut_fold_ulint_pair(fold, (ulint)(*str));
str++;
}
return(fold);
}
#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);
}
|
