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Annotation of embedaddon/php/ext/standard/lcg.c, revision 1.1.1.2

1.1       misho       1: /*
                      2:    +----------------------------------------------------------------------+
                      3:    | PHP Version 5                                                        |
                      4:    +----------------------------------------------------------------------+
                      5:    | Copyright (c) 1997-2012 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: 
1.1.1.2 ! misho      19: /* $Id$ */
1.1       misho      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
                     35: int lcg_globals_id;
                     36: #else
                     37: static 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: 
                     53: static void lcg_seed(TSRMLS_D);
                     54: 
                     55: PHPAPI 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: 
                     76: static 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: 
                    100: static void lcg_init_globals(php_lcg_globals *lcg_globals_p TSRMLS_DC) /* {{{ */
                    101: {
                    102:        LCG(seeded) = 0;
                    103: }
                    104: /* }}} */
                    105: 
                    106: PHP_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 */
                    119: PHP_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:  */