1 /*
2 +----------------------------------------------------------------------+
3 | PHP Version 7 |
4 +----------------------------------------------------------------------+
5 | Copyright (c) 1997-2018 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 #include "php.h"
20 #include "php_lcg.h"
21
22 #if HAVE_UNISTD_H
23 #include <unistd.h>
24 #endif
25
26 #ifdef PHP_WIN32
27 #include "win32/time.h"
28 #else
29 #include <sys/time.h>
30 #endif
31
32 #ifdef ZTS
33 int lcg_globals_id;
34 #else
35 static php_lcg_globals lcg_globals;
36 #endif
37
38 #ifdef PHP_WIN32
39 #include <process.h>
40 #endif
41
42 /*
43 * combinedLCG() returns a pseudo random number in the range of (0, 1).
44 * The function combines two CGs with periods of
45 * 2^31 - 85 and 2^31 - 249. The period of this function
46 * is equal to the product of both primes.
47 */
48
49 #define MODMULT(a, b, c, m, s) q = s/a;s=b*(s-a*q)-c*q;if(s<0)s+=m
50
51 static void lcg_seed(void);
52
php_combined_lcg(void)53 PHPAPI double php_combined_lcg(void) /* {{{ */
54 {
55 int32_t q;
56 int32_t z;
57
58 if (!LCG(seeded)) {
59 lcg_seed();
60 }
61
62 MODMULT(53668, 40014, 12211, 2147483563L, LCG(s1));
63 MODMULT(52774, 40692, 3791, 2147483399L, LCG(s2));
64
65 z = LCG(s1) - LCG(s2);
66 if (z < 1) {
67 z += 2147483562;
68 }
69
70 return z * 4.656613e-10;
71 }
72 /* }}} */
73
lcg_seed(void)74 static void lcg_seed(void) /* {{{ */
75 {
76 struct timeval tv;
77
78 if (gettimeofday(&tv, NULL) == 0) {
79 LCG(s1) = tv.tv_sec ^ (tv.tv_usec<<11);
80 } else {
81 LCG(s1) = 1;
82 }
83 #ifdef ZTS
84 LCG(s2) = (zend_long) tsrm_thread_id();
85 #else
86 LCG(s2) = (zend_long) getpid();
87 #endif
88
89 /* Add entropy to s2 by calling gettimeofday() again */
90 if (gettimeofday(&tv, NULL) == 0) {
91 LCG(s2) ^= (tv.tv_usec<<11);
92 }
93
94 LCG(seeded) = 1;
95 }
96 /* }}} */
97
lcg_init_globals(php_lcg_globals * lcg_globals_p)98 static void lcg_init_globals(php_lcg_globals *lcg_globals_p) /* {{{ */
99 {
100 LCG(seeded) = 0;
101 }
102 /* }}} */
103
PHP_MINIT_FUNCTION(lcg)104 PHP_MINIT_FUNCTION(lcg) /* {{{ */
105 {
106 #ifdef ZTS
107 ts_allocate_id(&lcg_globals_id, sizeof(php_lcg_globals), (ts_allocate_ctor) lcg_init_globals, NULL);
108 #else
109 lcg_init_globals(&lcg_globals);
110 #endif
111 return SUCCESS;
112 }
113 /* }}} */
114
115 /* {{{ proto float lcg_value()
116 Returns a value from the combined linear congruential generator */
PHP_FUNCTION(lcg_value)117 PHP_FUNCTION(lcg_value)
118 {
119 if (zend_parse_parameters_none() == FAILURE) {
120 return;
121 }
122 RETURN_DOUBLE(php_combined_lcg());
123 }
124 /* }}} */
125
126 /*
127 * Local variables:
128 * tab-width: 4
129 * c-basic-offset: 4
130 * End:
131 * vim600: sw=4 ts=4 fdm=marker
132 * vim<600: sw=4 ts=4
133 */
134
