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89 lines
2.4 KiB
C
89 lines
2.4 KiB
C
/*
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+----------------------------------------------------------------------+
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| PHP version 4.0 |
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+----------------------------------------------------------------------+
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| Copyright (c) 1997, 1998, 1999, 2000 The PHP Group |
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+----------------------------------------------------------------------+
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| This source file is subject to version 2.01 of the PHP license, |
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| that is bundled with this package in the file LICENSE, and is |
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| available at through the world-wide-web at |
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| http://www.php.net/license/2_01.txt. |
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| If you did not receive a copy of the PHP license and are unable to |
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| obtain it through the world-wide-web, please send a note to |
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| license@php.net so we can mail you a copy immediately. |
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+----------------------------------------------------------------------+
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| Authors: Sascha Schumann <ss@2ns.de> |
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+----------------------------------------------------------------------+
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*/
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#include "php.h"
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#include "php_lcg.h"
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#ifdef ZTS
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int lcg_globals_id;
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#else
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static php_lcg_globals lcg_globals;
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#endif
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#ifdef PHP_WIN32
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#include <process.h>
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#endif
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/*
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* combinedLCG() returns a pseudo random number in the range of (0,1).
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* The function combines two CGs with periods of
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* 2^31 - 85 and 2^31 - 249. The period of this function
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* is equal to the product of both primes.
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*/
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#define MODMULT(a,b,c,m,s) q = s/a;s=b*(s-a*q)-c*q;if(s<0)s+=m
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double php_combined_lcg(void)
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{
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long q;
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long z;
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LCGLS_FETCH();
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MODMULT(53668,40014,12211,2147483563L, LCG(s1));
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MODMULT(52774,40692,3791, 2147483399L, LCG(s2));
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z = LCG(s1) - LCG(s2);
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if(z < 1) {
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z += 2147483562;
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}
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return z * 4.656613e-10;
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}
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static void lcg_init_globals(LCGLS_D)
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{
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LCG(s1) = 1;
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#ifdef ZTS
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LCG(s2) = (long) tsrm_thread_id();
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#else
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LCG(s2) = (long) getpid();
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#endif
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}
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PHP_MINIT_FUNCTION(lcg)
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{
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#ifdef ZTS
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lcg_globals_id = ts_allocate_id(sizeof(php_lcg_globals), (ts_allocate_ctor) lcg_init_globals, NULL);
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#else
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lcg_init_globals();
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#endif
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return SUCCESS;
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}
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/* {{{ proto double lcg_value()
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Returns a value from the combined linear congruential generator */
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PHP_FUNCTION(lcg_value)
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{
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RETURN_DOUBLE(php_combined_lcg());
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}
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/* }}} */
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