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| author | Sterling Hughes <sterling@php.net> | 2001-09-16 03:46:59 +0000 |
|---|---|---|
| committer | Sterling Hughes <sterling@php.net> | 2001-09-16 03:46:59 +0000 |
| commit | 373fc12bb1a985c10792050b5e50998f762d2cbb (patch) | |
| tree | d0ad73b84dc87d49def9c58cf0385f512865d3a7 /ext/standard/rand.c | |
| parent | d477d490b2a06ea7fcc924263888881499ad6dd4 (diff) | |
| download | php-git-373fc12bb1a985c10792050b5e50998f762d2cbb.tar.gz | |
@ Make the seed options to srand() and mt_srand() optional, if the seed is
@ not specified, the generate the most random seed possible. (Sterling)
Please, if anyone has any comments on the way I generate this seed, speak up!
This seems to be the most "random" seed I could come up with...
This commit is 100% backwards compatible :)
Add myself to the authors list cause of recent work on the file
Diffstat (limited to 'ext/standard/rand.c')
| -rw-r--r-- | ext/standard/rand.c | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/ext/standard/rand.c b/ext/standard/rand.c index 3be2165303..8cde64300b 100644 --- a/ext/standard/rand.c +++ b/ext/standard/rand.c @@ -15,6 +15,7 @@ | Authors: Rasmus Lerdorf <rasmus@lerdorf.on.ca> | | Zeev Suraski <zeev@zend.com> | | Pedro Melo <melo@ip.pt> | + | Sterling Hughes <sterling@php.net> | | | | Based on code from: Shawn Cokus <Cokus@math.washington.edu> | +----------------------------------------------------------------------+ @@ -112,6 +113,7 @@ PHPAPI void php_mt_srand(php_uint32 seed TSRMLS_DC) 2^31, 2^31, 2^31, ...; 2^30, 2^30, 2^30, ...; 2^29, 2^29 + 2^31, 2^29, 2^29 + 2^31, ..., etc. so I force seed to be odd below. + Even if x_initial is odd, if x_initial is 1 mod 4 then the lowest bit of x is always 1, @@ -190,28 +192,36 @@ PHPAPI php_uint32 php_mt_rand(TSRMLS_D) return y ^ (y >> 18); } -/* {{{ proto void srand(int seed) +#define GENERATE_SEED() (time(0) * getpid() * 1000000 * php_combined_lcg(TSRMLS_C)) + +/* {{{ proto void srand([int seed]) Seeds random number generator */ PHP_FUNCTION(srand) { - long seed; + long seed = 0; - if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l", &seed) == FAILURE) + if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "|l", &seed) == FAILURE) return; + if (!seed) + seed = GENERATE_SEED(); + php_srand(seed); } /* }}} */ -/* {{{ proto void mt_srand(int seed) +/* {{{ proto void mt_srand([int seed]) Seeds Mersenne Twister random number generator */ PHP_FUNCTION(mt_srand) { - long seed; + long seed = 0; - if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l", &seed) == FAILURE) + if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "|l", &seed) == FAILURE) return; + if (!seed) + seed = GENERATE_SEED(); + php_mt_srand(seed TSRMLS_CC); } /* }}} */ |