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
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
|
/*****************************************************************************
Copyright (c) 1994, 2013, Oracle and/or its affiliates. All Rights Reserved.
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, Suite 500, 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
#define UT_RND1 151117737
#define UT_RND2 119785373
#define UT_RND3 85689495
#define UT_RND4 76595339
#define UT_SUM_RND2 98781234
#define UT_SUM_RND3 126792457
#define UT_SUM_RND4 63498502
#define UT_XOR_RND1 187678878
#define UT_XOR_RND2 143537923
/** Seed value of ut_rnd_gen_ulint() */
extern ulint ut_rnd_ulint_counter;
/********************************************************//**
This is used to set the random number seed. */
UNIV_INLINE
void
ut_rnd_set_seed(
/*============*/
ulint seed) /*!< in: seed */
{
ut_rnd_ulint_counter = seed;
}
/********************************************************//**
The following function generates a series of 'random' ulint integers.
@return the next 'random' number */
UNIV_INLINE
ulint
ut_rnd_gen_next_ulint(
/*==================*/
ulint rnd) /*!< in: the previous random number value */
{
ulint n_bits;
n_bits = 8 * sizeof(ulint);
rnd = UT_RND2 * rnd + UT_SUM_RND3;
rnd = UT_XOR_RND1 ^ rnd;
rnd = (rnd << 20) + (rnd >> (n_bits - 20));
rnd = UT_RND3 * rnd + UT_SUM_RND4;
rnd = UT_XOR_RND2 ^ rnd;
rnd = (rnd << 20) + (rnd >> (n_bits - 20));
rnd = UT_RND1 * rnd + UT_SUM_RND2;
return(rnd);
}
/********************************************************//**
The following function generates 'random' ulint integers which
enumerate the value space of ulint integers in a pseudo random
fashion. Note that the same integer is repeated always after
2 to power 32 calls to the generator (if ulint is 32-bit).
@return the 'random' number */
UNIV_INLINE
ulint
ut_rnd_gen_ulint(void)
/*==================*/
{
ulint rnd;
ut_rnd_ulint_counter = UT_RND1 * ut_rnd_ulint_counter + UT_RND2;
rnd = ut_rnd_gen_next_ulint(ut_rnd_ulint_counter);
return(rnd);
}
/********************************************************//**
Generates a random integer from a given interval.
@return the 'random' number */
UNIV_INLINE
ulint
ut_rnd_interval(
/*============*/
ulint low, /*!< in: low limit; can generate also this value */
ulint high) /*!< in: high limit; can generate also this value */
{
ulint rnd;
ut_ad(high >= low);
if (low == high) {
return(low);
}
rnd = ut_rnd_gen_ulint();
return(low + (rnd % (high - low)));
}
/*******************************************************//**
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++));
case 6:
fold = ut_fold_ulint_pair(fold, (ulint)(*str++));
case 5:
fold = ut_fold_ulint_pair(fold, (ulint)(*str++));
case 4:
fold = ut_fold_ulint_pair(fold, (ulint)(*str++));
case 3:
fold = ut_fold_ulint_pair(fold, (ulint)(*str++));
case 2:
fold = ut_fold_ulint_pair(fold, (ulint)(*str++));
case 1:
fold = ut_fold_ulint_pair(fold, (ulint)(*str++));
}
return(fold);
}
|