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|
/*
+----------------------------------------------------------------------+
| PHP version 4.0 |
+----------------------------------------------------------------------+
| Copyright (c) 1997, 1998, 1999 The PHP Group |
+----------------------------------------------------------------------+
| This source file is subject to version 2.0 of the PHP license, |
| that is bundled with this package in the file LICENSE, and is |
| available at through the world-wide-web at |
| http://www.php.net/license/2_0.txt. |
| If you did not receive a copy of the PHP license and are unable to |
| obtain it through the world-wide-web, please send a note to |
| license@php.net so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Authors: Sascha Schumann <ss@2ns.de> |
+----------------------------------------------------------------------+
*/
#include "php.h"
#include "php_lcg.h"
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef ZTS
int lcg_globals_id;
#else
static php_lcg_globals lcg_globals;
#endif
#if WIN32||WINNT
#include <process.h>
#endif
/*
* combinedLCG() returns a pseudo random number in the range of (0,1).
* The function combines two CGs with periods of
* 2^31 - 85 and 2^31 - 249. The period of this function
* is equal to the product of both primes.
*/
#define MODMULT(a,b,c,m,s) q = s/a;s=b*(s-a*q)-c*q;if(s<0)s+=m
double php_combined_lcg(void)
{
long q;
long z;
LCGLS_FETCH();
MODMULT(53668,40014,12211,2147483563L, LCG(s1));
MODMULT(52774,40692,3791, 2147483399L, LCG(s2));
z = LCG(s1) - LCG(s2);
if(z < 1) {
z += 2147483562;
}
return z * 4.656613e-10;
}
static void lcg_init_globals(LCGLS_D)
{
LCG(s1) = 1;
#ifdef ZTS
LCG(s2) = (long) tsrm_thread_id();
#else
LCG(s2) = (long) getpid();
#endif
}
static int php_minit_lcg(INIT_FUNC_ARGS)
{
#ifdef ZTS
lcg_globals_id = ts_allocate_id(sizeof(php_lcg_globals), (ts_allocate_ctor) lcg_init_globals, NULL);
#else
lcg_init_globals();
#endif
return SUCCESS;
}
/* {{{ proto double lcg_value()
returns a value from the combined linear congruential generator */
PHP_FUNCTION(lcg_value)
{
RETURN_DOUBLE(php_combined_lcg());
}
/* }}} */
static function_entry lcg_functions[] = {
PHP_FE(lcg_value, NULL)
{0}
};
zend_module_entry lcg_module_entry = {
"LCG",
lcg_functions,
php_minit_lcg, NULL,
NULL, NULL,
NULL,
STANDARD_MODULE_PROPERTIES
};
|
