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Annotation of embedaddon/php/ext/standard/lcg.c, revision 1.1

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: 
        !            19: /* $Id: lcg.c 321634 2012-01-01 13:15:04Z felipe $ */
        !            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:  */