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133 lines
3.1 KiB
C
133 lines
3.1 KiB
C
/*
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+----------------------------------------------------------------------+
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| PHP Version 7 |
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+----------------------------------------------------------------------+
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| Copyright (c) 1997-2016 The PHP Group |
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+----------------------------------------------------------------------+
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| This source file is subject to version 3.01 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 through the world-wide-web at the following url: |
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| http://www.php.net/license/3_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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| Author: 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 PHP_WIN32
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#include "win32/time.h"
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#else
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#include <sys/time.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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static void lcg_seed(void);
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PHPAPI double php_combined_lcg(void) /* {{{ */
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{
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php_int32 q;
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php_int32 z;
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if (!LCG(seeded)) {
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lcg_seed();
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}
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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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/* }}} */
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static void lcg_seed(void) /* {{{ */
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{
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struct timeval tv;
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if (gettimeofday(&tv, NULL) == 0) {
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LCG(s1) = tv.tv_sec ^ (tv.tv_usec<<11);
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} else {
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LCG(s1) = 1;
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}
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#ifdef ZTS
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LCG(s2) = (zend_long) tsrm_thread_id();
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#else
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LCG(s2) = (zend_long) getpid();
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#endif
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/* Add entropy to s2 by calling gettimeofday() again */
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if (gettimeofday(&tv, NULL) == 0) {
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LCG(s2) ^= (tv.tv_usec<<11);
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}
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LCG(seeded) = 1;
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}
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/* }}} */
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static void lcg_init_globals(php_lcg_globals *lcg_globals_p) /* {{{ */
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{
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LCG(seeded) = 0;
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}
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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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ts_allocate_id(&lcg_globals_id, sizeof(php_lcg_globals), (ts_allocate_ctor) lcg_init_globals, NULL);
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#else
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lcg_init_globals(&lcg_globals);
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#endif
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return SUCCESS;
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}
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/* }}} */
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/* {{{ proto float 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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/*
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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 fdm=marker
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* vim<600: sw=4 ts=4
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*/
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