mariadb/ut/ut0rnd.c
marko 1601bdc38a branches/innodb+: Merge revisions 5091:5143 from branches/zip:
------------------------------------------------------------------------
  r5092 | marko | 2009-05-25 09:54:17 +0300 (Mon, 25 May 2009) | 1 line

  branches/zip: Adjust some function comments after r5091.
  ------------------------------------------------------------------------
  r5100 | marko | 2009-05-25 12:09:45 +0300 (Mon, 25 May 2009) | 1 line

  branches/zip: Split some long lines that were introduced in r5091.
  ------------------------------------------------------------------------
  r5101 | marko | 2009-05-25 12:42:47 +0300 (Mon, 25 May 2009) | 2 lines

  branches/zip: Introduce the macro TEMP_INDEX_PREFIX_STR.
  This is to avoid triggering an error in Doxygen.
  ------------------------------------------------------------------------
  r5102 | marko | 2009-05-25 13:47:14 +0300 (Mon, 25 May 2009) | 1 line

  branches/zip: Add missing file comments.
  ------------------------------------------------------------------------
  r5103 | marko | 2009-05-25 13:52:29 +0300 (Mon, 25 May 2009) | 10 lines

  branches/zip: Add @file comments, and convert decorative
  /*********************************
  comments to Doxygen /** style like this:
  /*****************************//**

  This conversion was performed by the following command:

  perl -i -e 'while(<ARGV>){if (m|^/\*{30}\**$|) {
  s|\*{4}$|//**| if ++$com>1; $_ .= "\@file $ARGV\n" if $com==2}
  print; if(eof){$.=0;undef $com}}' */*[ch] include/univ.i
  ------------------------------------------------------------------------
  r5104 | marko | 2009-05-25 14:39:07 +0300 (Mon, 25 May 2009) | 2 lines

  branches/zip: Revert ut0auxconf_* to r5102,
  that is, make Doxygen ignore these test programs.
  ------------------------------------------------------------------------
  r5105 | marko | 2009-05-25 14:52:20 +0300 (Mon, 25 May 2009) | 2 lines

  branches/zip: Enclose some #error checks inside #ifndef DOXYGEN
  to prevent bogus Doxygen errors.
  ------------------------------------------------------------------------
  r5106 | marko | 2009-05-25 16:09:24 +0300 (Mon, 25 May 2009) | 2 lines

  branches/zip: Add some Doxygen comments, mainly to structs, typedefs,
  macros and global variables.  Many more to go.
  ------------------------------------------------------------------------
  r5108 | marko | 2009-05-26 00:32:35 +0300 (Tue, 26 May 2009) | 2 lines

  branches/zip: lexyy.c: Remove the inadvertently added @file directive.
  There is nothing for Doxygen to see in this file, move along.
  ------------------------------------------------------------------------
  r5125 | marko | 2009-05-26 16:28:49 +0300 (Tue, 26 May 2009) | 3 lines

  branches/zip: Add some Doxygen comments for many structs, typedefs,
  #defines and global variables.  Many are still missing.
  ------------------------------------------------------------------------
  r5134 | marko | 2009-05-27 09:08:43 +0300 (Wed, 27 May 2009) | 1 line

  branches/zip: Add some Doxygen @return comments.
  ------------------------------------------------------------------------
  r5139 | marko | 2009-05-27 10:01:40 +0300 (Wed, 27 May 2009) | 1 line

  branches/zip: Add Doxyfile.
  ------------------------------------------------------------------------
  r5143 | marko | 2009-05-27 10:57:25 +0300 (Wed, 27 May 2009) | 3 lines

  branches/zip: buf0buf.h, Doxyfile: Fix the Doxygen translation.
  @defgroup is for source code modules, not for field groups.
  Tell Doxygen to expand the UT_LIST declarations.
  ------------------------------------------------------------------------
2009-05-27 09:52:16 +00:00

97 lines
2.3 KiB
C

/*****************************************************************************
Copyright (c) 1994, 2009, Innobase Oy. 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., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA
*****************************************************************************/
/***************************************************************//**
@file ut/ut0rnd.c
Random numbers and hashing
Created 5/11/1994 Heikki Tuuri
********************************************************************/
#include "ut0rnd.h"
#ifdef UNIV_NONINL
#include "ut0rnd.ic"
#endif
/** These random numbers are used in ut_find_prime */
/*@{*/
#define UT_RANDOM_1 1.0412321
#define UT_RANDOM_2 1.1131347
#define UT_RANDOM_3 1.0132677
/*@}*/
/** Seed value of ut_rnd_gen_ulint(). */
UNIV_INTERN ulint ut_rnd_ulint_counter = 65654363;
/***********************************************************//**
Looks for a prime number slightly greater than the given argument.
The prime is chosen so that it is not near any power of 2.
@return prime */
UNIV_INTERN
ulint
ut_find_prime(
/*==========*/
ulint n) /*!< in: positive number > 100 */
{
ulint pow2;
ulint i;
n += 100;
pow2 = 1;
while (pow2 * 2 < n) {
pow2 = 2 * pow2;
}
if ((double)n < 1.05 * (double)pow2) {
n = (ulint) ((double)n * UT_RANDOM_1);
}
pow2 = 2 * pow2;
if ((double)n > 0.95 * (double)pow2) {
n = (ulint) ((double)n * UT_RANDOM_2);
}
if (n > pow2 - 20) {
n += 30;
}
/* Now we have n far enough from powers of 2. To make
n more random (especially, if it was not near
a power of 2), we then multiply it by a random number. */
n = (ulint) ((double)n * UT_RANDOM_3);
for (;; n++) {
i = 2;
while (i * i <= n) {
if (n % i == 0) {
goto next_n;
}
i++;
}
/* Found a prime */
break;
next_n: ;
}
return(n);
}