1 /*
2 +----------------------------------------------------------------------+
3 | Copyright (c) The PHP Group |
4 +----------------------------------------------------------------------+
5 | This source file is subject to version 3.01 of the PHP license, |
6 | that is bundled with this package in the file LICENSE, and is |
7 | available through the world-wide-web at the following url: |
8 | http://www.php.net/license/3_01.txt |
9 | If you did not receive a copy of the PHP license and are unable to |
10 | obtain it through the world-wide-web, please send a note to |
11 | license@php.net so we can mail you a copy immediately. |
12 +----------------------------------------------------------------------+
13 | Author: Sascha Schumann <sascha@schumann.cx> |
14 +----------------------------------------------------------------------+
15 */
16
17 #include "php.h"
18 #include "php_lcg.h"
19
20 #if HAVE_UNISTD_H
21 #include <unistd.h>
22 #endif
23
24 #ifdef PHP_WIN32
25 #include "win32/time.h"
26 #else
27 #include <sys/time.h>
28 #endif
29
30 #ifdef ZTS
31 int lcg_globals_id;
32 #else
33 static php_lcg_globals lcg_globals;
34 #endif
35
36 #ifdef PHP_WIN32
37 #include <process.h>
38 #endif
39
40 /*
41 * combinedLCG() returns a pseudo random number in the range of (0, 1).
42 * The function combines two CGs with periods of
43 * 2^31 - 85 and 2^31 - 249. The period of this function
44 * is equal to the product of both primes.
45 */
46
47 #define MODMULT(a, b, c, m, s) q = s/a;s=b*(s-a*q)-c*q;if(s<0)s+=m
48
49 static void lcg_seed(void);
50
php_combined_lcg(void)51 PHPAPI double php_combined_lcg(void) /* {{{ */
52 {
53 int32_t q;
54 int32_t z;
55
56 if (!LCG(seeded)) {
57 lcg_seed();
58 }
59
60 MODMULT(53668, 40014, 12211, 2147483563L, LCG(s1));
61 MODMULT(52774, 40692, 3791, 2147483399L, LCG(s2));
62
63 z = LCG(s1) - LCG(s2);
64 if (z < 1) {
65 z += 2147483562;
66 }
67
68 return z * 4.656613e-10;
69 }
70 /* }}} */
71
lcg_seed(void)72 static void lcg_seed(void) /* {{{ */
73 {
74 struct timeval tv;
75
76 if (gettimeofday(&tv, NULL) == 0) {
77 LCG(s1) = tv.tv_sec ^ (tv.tv_usec<<11);
78 } else {
79 LCG(s1) = 1;
80 }
81 #ifdef ZTS
82 LCG(s2) = (zend_long) tsrm_thread_id();
83 #else
84 LCG(s2) = (zend_long) getpid();
85 #endif
86
87 /* Add entropy to s2 by calling gettimeofday() again */
88 if (gettimeofday(&tv, NULL) == 0) {
89 LCG(s2) ^= (tv.tv_usec<<11);
90 }
91
92 LCG(seeded) = 1;
93 }
94 /* }}} */
95
lcg_init_globals(php_lcg_globals * lcg_globals_p)96 static void lcg_init_globals(php_lcg_globals *lcg_globals_p) /* {{{ */
97 {
98 LCG(seeded) = 0;
99 }
100 /* }}} */
101
PHP_MINIT_FUNCTION(lcg)102 PHP_MINIT_FUNCTION(lcg) /* {{{ */
103 {
104 #ifdef ZTS
105 ts_allocate_id(&lcg_globals_id, sizeof(php_lcg_globals), (ts_allocate_ctor) lcg_init_globals, NULL);
106 #else
107 lcg_init_globals(&lcg_globals);
108 #endif
109 return SUCCESS;
110 }
111 /* }}} */
112
113 /* {{{ Returns a value from the combined linear congruential generator */
PHP_FUNCTION(lcg_value)114 PHP_FUNCTION(lcg_value)
115 {
116 ZEND_PARSE_PARAMETERS_NONE();
117
118 RETURN_DOUBLE(php_combined_lcg());
119 }
120 /* }}} */
121
