1/*
2 +----------------------------------------------------------------------+
3 | PHP Version 5 |
4 +----------------------------------------------------------------------+
5 | Copyright (c) 1997-2015 The PHP Group |
6 +----------------------------------------------------------------------+
7 | This source file is subject to version 3.01 of the PHP license, |
8 | that is bundled with this package in the file LICENSE, and is |
9 | available through the world-wide-web at the following url: |
10 | http://www.php.net/license/3_01.txt |
11 | If you did not receive a copy of the PHP license and are unable to |
12 | obtain it through the world-wide-web, please send a note to |
13 | license@php.net so we can mail you a copy immediately. |
14 +----------------------------------------------------------------------+
15 | Author: Sascha Schumann <sascha@schumann.cx> |
16 +----------------------------------------------------------------------+
17*/
18
19/* $Id$ */
20
21#include "php.h"
22#include "php_lcg.h"
23
24#if HAVE_UNISTD_H
25#include <unistd.h>
26#endif
27
28#ifdef PHP_WIN32
29#include "win32/time.h"
30#else
31#include <sys/time.h>
32#endif
33
34#ifdef ZTS
35int lcg_globals_id;
36#else
37static php_lcg_globals lcg_globals;
38#endif
39
40#ifdef PHP_WIN32
41#include <process.h>
42#endif
43
44/*
45 * combinedLCG() returns a pseudo random number in the range of (0, 1).
46 * The function combines two CGs with periods of
47 * 2^31 - 85 and 2^31 - 249. The period of this function
48 * is equal to the product of both primes.
49 */
50
51#define MODMULT(a, b, c, m, s) q = s/a;s=b*(s-a*q)-c*q;if(s<0)s+=m
52
53static void lcg_seed(TSRMLS_D);
54
55PHPAPI double php_combined_lcg(TSRMLS_D) /* {{{ */
56{
57 php_int32 q;
58 php_int32 z;
59
60 if (!LCG(seeded)) {
61 lcg_seed(TSRMLS_C);
62 }
63
64 MODMULT(53668, 40014, 12211, 2147483563L, LCG(s1));
65 MODMULT(52774, 40692, 3791, 2147483399L, LCG(s2));
66
67 z = LCG(s1) - LCG(s2);
68 if (z < 1) {
69 z += 2147483562;
70 }
71
72 return z * 4.656613e-10;
73}
74/* }}} */
75
76static void lcg_seed(TSRMLS_D) /* {{{ */
77{
78 struct timeval tv;
79
80 if (gettimeofday(&tv, NULL) == 0) {
81 LCG(s1) = tv.tv_sec ^ (tv.tv_usec<<11);
82 } else {
83 LCG(s1) = 1;
84 }
85#ifdef ZTS
86 LCG(s2) = (long) tsrm_thread_id();
87#else
88 LCG(s2) = (long) getpid();
89#endif
90
91 /* Add entropy to s2 by calling gettimeofday() again */
92 if (gettimeofday(&tv, NULL) == 0) {
93 LCG(s2) ^= (tv.tv_usec<<11);
94 }
95
96 LCG(seeded) = 1;
97}
98/* }}} */
99
100static void lcg_init_globals(php_lcg_globals *lcg_globals_p TSRMLS_DC) /* {{{ */
101{
102 LCG(seeded) = 0;
103}
104/* }}} */
105
106PHP_MINIT_FUNCTION(lcg) /* {{{ */
107{
108#ifdef ZTS
109 ts_allocate_id(&lcg_globals_id, sizeof(php_lcg_globals), (ts_allocate_ctor) lcg_init_globals, NULL);
110#else
111 lcg_init_globals(&lcg_globals);
112#endif
113 return SUCCESS;
114}
115/* }}} */
116
117/* {{{ proto float lcg_value()
118 Returns a value from the combined linear congruential generator */
119PHP_FUNCTION(lcg_value)
120{
121 RETURN_DOUBLE(php_combined_lcg(TSRMLS_C));
122}
123/* }}} */
124
125/*
126 * Local variables:
127 * tab-width: 4
128 * c-basic-offset: 4
129 * End:
130 * vim600: sw=4 ts=4 fdm=marker
131 * vim<600: sw=4 ts=4
132 */
133