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a0724d3081
This reverts commit 6f6bd8ce53.
`mt_rand()` is seedable with `mt_srand()` which means it can be used to (re)produce specific streams of numbers. All code (no matter how few instances that may be) that previously depended on this behaviour will no longer produce the same results.
This kind of change needs to be discussed before being committed.
383 lines
11 KiB
C
383 lines
11 KiB
C
/*
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+----------------------------------------------------------------------+
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| PHP Version 7 |
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+----------------------------------------------------------------------+
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| Copyright (c) 1997-2016 The PHP Group |
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+----------------------------------------------------------------------+
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| This source file is subject to version 3.01 of the PHP license, |
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| that is bundled with this package in the file LICENSE, and is |
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| available through the world-wide-web at the following url: |
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| http://www.php.net/license/3_01.txt |
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| If you did not receive a copy of the PHP license and are unable to |
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| obtain it through the world-wide-web, please send a note to |
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| license@php.net so we can mail you a copy immediately. |
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+----------------------------------------------------------------------+
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| Authors: Rasmus Lerdorf <rasmus@php.net> |
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| Zeev Suraski <zeev@zend.com> |
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| Pedro Melo <melo@ip.pt> |
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| Sterling Hughes <sterling@php.net> |
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| |
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| Based on code from: Richard J. Wagner <rjwagner@writeme.com> |
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| Makoto Matsumoto <matumoto@math.keio.ac.jp> |
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| Takuji Nishimura |
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| Shawn Cokus <Cokus@math.washington.edu> |
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+----------------------------------------------------------------------+
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*/
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/* $Id$ */
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#include <stdlib.h>
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#include "php.h"
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#include "php_math.h"
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#include "php_rand.h"
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#include "basic_functions.h"
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/* SYSTEM RAND FUNCTIONS */
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/* {{{ php_srand
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*/
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PHPAPI void php_srand(zend_long seed)
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{
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#ifdef ZTS
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BG(rand_seed) = (unsigned int) seed;
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#else
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# if defined(HAVE_SRANDOM)
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srandom((unsigned int) seed);
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# elif defined(HAVE_SRAND48)
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srand48(seed);
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# else
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srand((unsigned int) seed);
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# endif
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#endif
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/* Seed only once */
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BG(rand_is_seeded) = 1;
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}
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/* }}} */
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/* {{{ php_rand
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*/
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PHPAPI zend_long php_rand(void)
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{
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zend_long ret;
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if (!BG(rand_is_seeded)) {
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php_srand(GENERATE_SEED());
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}
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#ifdef ZTS
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ret = php_rand_r(&BG(rand_seed));
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#else
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# if defined(HAVE_RANDOM)
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ret = random();
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# elif defined(HAVE_LRAND48)
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ret = lrand48();
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# else
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ret = rand();
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# endif
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#endif
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return ret;
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}
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/* }}} */
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/* MT RAND FUNCTIONS */
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/*
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The following php_mt_...() functions are based on a C++ class MTRand by
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Richard J. Wagner. For more information see the web page at
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http://www-personal.engin.umich.edu/~wagnerr/MersenneTwister.html
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Mersenne Twister random number generator -- a C++ class MTRand
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Based on code by Makoto Matsumoto, Takuji Nishimura, and Shawn Cokus
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Richard J. Wagner v1.0 15 May 2003 rjwagner@writeme.com
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The Mersenne Twister is an algorithm for generating random numbers. It
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was designed with consideration of the flaws in various other generators.
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The period, 2^19937-1, and the order of equidistribution, 623 dimensions,
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are far greater. The generator is also fast; it avoids multiplication and
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division, and it benefits from caches and pipelines. For more information
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see the inventors' web page at http://www.math.keio.ac.jp/~matumoto/emt.html
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Reference
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M. Matsumoto and T. Nishimura, "Mersenne Twister: A 623-Dimensionally
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Equidistributed Uniform Pseudo-Random Number Generator", ACM Transactions on
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Modeling and Computer Simulation, Vol. 8, No. 1, January 1998, pp 3-30.
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Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
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Copyright (C) 2000 - 2003, Richard J. Wagner
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. The names of its contributors may not be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#define N MT_N /* length of state vector */
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#define M (397) /* a period parameter */
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#define hiBit(u) ((u) & 0x80000000U) /* mask all but highest bit of u */
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#define loBit(u) ((u) & 0x00000001U) /* mask all but lowest bit of u */
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#define loBits(u) ((u) & 0x7FFFFFFFU) /* mask the highest bit of u */
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#define mixBits(u, v) (hiBit(u)|loBits(v)) /* move hi bit of u to hi bit of v */
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#define twist(m,u,v) (m ^ (mixBits(u,v)>>1) ^ ((php_uint32)(-(php_int32)(loBit(u))) & 0x9908b0dfU))
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/* {{{ php_mt_initialize
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*/
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static inline void php_mt_initialize(php_uint32 seed, php_uint32 *state)
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{
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/* Initialize generator state with seed
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See Knuth TAOCP Vol 2, 3rd Ed, p.106 for multiplier.
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In previous versions, most significant bits (MSBs) of the seed affect
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only MSBs of the state array. Modified 9 Jan 2002 by Makoto Matsumoto. */
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register php_uint32 *s = state;
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register php_uint32 *r = state;
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register int i = 1;
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*s++ = seed & 0xffffffffU;
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for( ; i < N; ++i ) {
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*s++ = ( 1812433253U * ( *r ^ (*r >> 30) ) + i ) & 0xffffffffU;
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r++;
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}
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}
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/* }}} */
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/* {{{ php_mt_reload
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*/
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static inline void php_mt_reload(void)
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{
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/* Generate N new values in state
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Made clearer and faster by Matthew Bellew (matthew.bellew@home.com) */
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register php_uint32 *state = BG(state);
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register php_uint32 *p = state;
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register int i;
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for (i = N - M; i--; ++p)
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*p = twist(p[M], p[0], p[1]);
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for (i = M; --i; ++p)
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*p = twist(p[M-N], p[0], p[1]);
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*p = twist(p[M-N], p[0], state[0]);
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BG(left) = N;
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BG(next) = state;
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}
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/* }}} */
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/* {{{ php_mt_srand
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*/
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PHPAPI void php_mt_srand(php_uint32 seed)
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{
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/* Seed the generator with a simple uint32 */
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php_mt_initialize(seed, BG(state));
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php_mt_reload();
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/* Seed only once */
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BG(mt_rand_is_seeded) = 1;
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}
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/* }}} */
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/* {{{ php_mt_rand
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*/
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PHPAPI php_uint32 php_mt_rand(void)
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{
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/* Pull a 32-bit integer from the generator state
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Every other access function simply transforms the numbers extracted here */
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register php_uint32 s1;
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if (BG(left) == 0) {
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php_mt_reload();
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}
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--BG(left);
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s1 = *BG(next)++;
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s1 ^= (s1 >> 11);
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s1 ^= (s1 << 7) & 0x9d2c5680U;
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s1 ^= (s1 << 15) & 0xefc60000U;
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return ( s1 ^ (s1 >> 18) );
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}
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/* }}} */
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/* {{{ proto void srand([int seed])
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Seeds random number generator */
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PHP_FUNCTION(srand)
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{
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zend_long seed = 0;
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if (zend_parse_parameters(ZEND_NUM_ARGS(), "|l", &seed) == FAILURE)
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return;
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if (ZEND_NUM_ARGS() == 0)
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seed = GENERATE_SEED();
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php_srand(seed);
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}
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/* }}} */
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/* {{{ proto void mt_srand([int seed])
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Seeds Mersenne Twister random number generator */
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PHP_FUNCTION(mt_srand)
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{
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zend_long seed = 0;
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if (zend_parse_parameters(ZEND_NUM_ARGS(), "|l", &seed) == FAILURE)
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return;
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if (ZEND_NUM_ARGS() == 0)
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seed = GENERATE_SEED();
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php_mt_srand(seed);
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}
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/* }}} */
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/*
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* A bit of tricky math here. We want to avoid using a modulus because
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* that simply tosses the high-order bits and might skew the distribution
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* of random values over the range. Instead we map the range directly.
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*
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* We need to map the range from 0...M evenly to the range a...b
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* Let n = the random number and n' = the mapped random number
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*
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* Then we have: n' = a + n(b-a)/M
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*
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* We have a problem here in that only n==M will get mapped to b which
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# means the chances of getting b is much much less than getting any of
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# the other values in the range. We can fix this by increasing our range
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# artificially and using:
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#
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# n' = a + n(b-a+1)/M
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*
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# Now we only have a problem if n==M which would cause us to produce a
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# number of b+1 which would be bad. So we bump M up by one to make sure
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# this will never happen, and the final algorithm looks like this:
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#
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# n' = a + n(b-a+1)/(M+1)
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*
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* -RL
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*/
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/* {{{ proto int rand([int min, int max])
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Returns a random number */
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PHP_FUNCTION(rand)
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{
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zend_long min;
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zend_long max;
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zend_long number;
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int argc = ZEND_NUM_ARGS();
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if (argc != 0 && zend_parse_parameters(argc, "ll", &min, &max) == FAILURE)
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return;
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number = php_rand();
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if (argc == 2) {
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RAND_RANGE(number, min, max, PHP_RAND_MAX);
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}
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RETURN_LONG(number);
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}
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/* }}} */
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/* {{{ proto int mt_rand([int min, int max])
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Returns a random number from Mersenne Twister */
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PHP_FUNCTION(mt_rand)
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{
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zend_long min;
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zend_long max;
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zend_long number;
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int argc = ZEND_NUM_ARGS();
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if (argc != 0) {
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if (zend_parse_parameters(argc, "ll", &min, &max) == FAILURE) {
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return;
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} else if (max < min) {
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php_error_docref(NULL, E_WARNING, "max(" ZEND_LONG_FMT ") is smaller than min(" ZEND_LONG_FMT ")", max, min);
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RETURN_FALSE;
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}
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}
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if (!BG(mt_rand_is_seeded)) {
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php_mt_srand(GENERATE_SEED());
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}
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/*
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* Melo: hmms.. randomMT() returns 32 random bits...
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* Yet, the previous php_rand only returns 31 at most.
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* So I put a right shift to loose the lsb. It *seems*
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* better than clearing the msb.
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* Update:
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* I talked with Cokus via email and it won't ruin the algorithm
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*/
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number = (zend_long) (php_mt_rand() >> 1);
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if (argc == 2) {
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RAND_RANGE(number, min, max, PHP_MT_RAND_MAX);
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}
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RETURN_LONG(number);
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}
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/* }}} */
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/* {{{ proto int getrandmax(void)
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Returns the maximum value a random number can have */
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PHP_FUNCTION(getrandmax)
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{
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if (zend_parse_parameters_none() == FAILURE) {
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return;
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}
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RETURN_LONG(PHP_RAND_MAX);
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}
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/* }}} */
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/* {{{ proto int mt_getrandmax(void)
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Returns the maximum value a random number from Mersenne Twister can have */
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PHP_FUNCTION(mt_getrandmax)
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{
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if (zend_parse_parameters_none() == FAILURE) {
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return;
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}
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/*
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* Melo: it could be 2^^32 but we only use 2^^31 to maintain
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* compatibility with the previous php_rand
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*/
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RETURN_LONG(PHP_MT_RAND_MAX); /* 2^^31 */
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}
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/* }}} */
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/*
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* Local variables:
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* tab-width: 4
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* c-basic-offset: 4
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* End:
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* vim600: noet sw=4 ts=4 fdm=marker
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* vim<600: noet sw=4 ts=4
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*/
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