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108 lines
2.7 KiB
C
108 lines
2.7 KiB
C
/*
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+----------------------------------------------------------------------+
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| PHP version 4.0 |
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+----------------------------------------------------------------------+
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| Copyright (c) 1997-2001 The PHP Group |
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+----------------------------------------------------------------------+
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| This source file is subject to version 2.02 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_02.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 <sascha@schumann.cx> |
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+----------------------------------------------------------------------+
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*/
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/* $Id$ */
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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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static int php_lcg_initialized = 0;
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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(TSRMLS_D)
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{
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php_int32 q;
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php_int32 z;
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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(php_lcg_globals *lcg_globals_p TSRMLS_DC)
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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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#ifdef ZTS
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PHP_MINIT_FUNCTION(lcg)
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{
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ts_allocate_id(&lcg_globals_id, sizeof(php_lcg_globals), (ts_allocate_ctor) lcg_init_globals, NULL);
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return SUCCESS;
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}
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#else
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PHP_RINIT_FUNCTION(lcg)
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{
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if (!php_lcg_initialized) {
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lcg_init_globals(&lcg_globals TSRMLS_CC);
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php_lcg_initialized = 1;
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}
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return SUCCESS;
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}
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#endif
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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(TSRMLS_C));
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}
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/* }}} */
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/*
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* Local variables:
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* tab-width: 4
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* c-basic-offset: 4
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* End:
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* vim600: sw=4 ts=4 tw=78 fdm=marker
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* vim<600: sw=4 ts=4 tw=78
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*/
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