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- /*
- +----------------------------------------------------------------------+
- | Copyright (c) The PHP Group |
- +----------------------------------------------------------------------+
- | This source file is subject to version 3.01 of the PHP license, |
- | that is bundled with this package in the file LICENSE, and is |
- | available through the world-wide-web at the following url: |
- | https://www.php.net/license/3_01.txt |
- | If you did not receive a copy of the PHP license and are unable to |
- | obtain it through the world-wide-web, please send a note to |
- | license@php.net so we can mail you a copy immediately. |
- +----------------------------------------------------------------------+
- | Authors: Rasmus Lerdorf <rasmus@php.net> |
- | Zeev Suraski <zeev@php.net> |
- | Pedro Melo <melo@ip.pt> |
- | Sterling Hughes <sterling@php.net> |
- | |
- | Based on code from: Shawn Cokus <Cokus@math.washington.edu> |
- +----------------------------------------------------------------------+
- */
- #ifndef PHP_RAND_H
- #define PHP_RAND_H
- #include "php_lcg.h"
- #include "php_mt_rand.h"
- /* System Rand functions */
- #ifndef RAND_MAX
- #define RAND_MAX PHP_MT_RAND_MAX
- #endif
- #define PHP_RAND_MAX PHP_MT_RAND_MAX
- /*
- * A bit of tricky math here. We want to avoid using a modulus because
- * that simply tosses the high-order bits and might skew the distribution
- * of random values over the range. Instead we map the range directly.
- *
- * We need to map the range from 0...M evenly to the range a...b
- * Let n = the random number and n' = the mapped random number
- *
- * Then we have: n' = a + n(b-a)/M
- *
- * We have a problem here in that only n==M will get mapped to b which
- # means the chances of getting b is much much less than getting any of
- # the other values in the range. We can fix this by increasing our range
- # artificially and using:
- #
- # n' = a + n(b-a+1)/M
- *
- # Now we only have a problem if n==M which would cause us to produce a
- # number of b+1 which would be bad. So we bump M up by one to make sure
- # this will never happen, and the final algorithm looks like this:
- #
- # n' = a + n(b-a+1)/(M+1)
- *
- * -RL
- */
- #define RAND_RANGE_BADSCALING(__n, __min, __max, __tmax) \
- (__n) = (__min) + (zend_long) ((double) ( (double) (__max) - (__min) + 1.0) * ((__n) / ((__tmax) + 1.0)))
- #ifdef PHP_WIN32
- #define GENERATE_SEED() (((zend_long) (time(0) * GetCurrentProcessId())) ^ ((zend_long) (1000000.0 * php_combined_lcg())))
- #else
- #define GENERATE_SEED() (((zend_long) (time(0) * getpid())) ^ ((zend_long) (1000000.0 * php_combined_lcg())))
- #endif
- PHPAPI void php_srand(zend_long seed);
- PHPAPI zend_long php_rand(void);
- #endif /* PHP_RAND_H */
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