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Diffstat (limited to 'ext/standard/rand.c')
-rw-r--r-- | ext/standard/rand.c | 358 |
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diff --git a/ext/standard/rand.c b/ext/standard/rand.c deleted file mode 100644 index 72227af0fd..0000000000 --- a/ext/standard/rand.c +++ /dev/null @@ -1,358 +0,0 @@ -/* - +----------------------------------------------------------------------+ - | PHP version 4.0 | - +----------------------------------------------------------------------+ - | Copyright (c) 1997-2001 The PHP Group | - +----------------------------------------------------------------------+ - | This source file is subject to version 2.02 of the PHP license, | - | that is bundled with this package in the file LICENSE, and is | - | available at through the world-wide-web at | - | http://www.php.net/license/2_02.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@lerdorf.on.ca> | - | Zeev Suraski <zeev@zend.com> | - | Pedro Melo <melo@ip.pt> | - | | - | Based on code from: Shawn Cokus <Cokus@math.washington.edu> | - +----------------------------------------------------------------------+ - */ -/* $Id$ */ - -#include <stdlib.h> - -#include "php.h" -#include "php_math.h" -#include "php_rand.h" - -#include "basic_functions.h" - -/* - This is the ``Mersenne Twister'' random number generator MT19937, which - generates pseudorandom integers uniformly distributed in 0..(2^32 - 1) - starting from any odd seed in 0..(2^32 - 1). This version is a recode - by Shawn Cokus (Cokus@math.washington.edu) on March 8, 1998 of a version by - Takuji Nishimura (who had suggestions from Topher Cooper and Marc Rieffel in - July-August 1997). - - Effectiveness of the recoding (on Goedel2.math.washington.edu, a DEC Alpha - running OSF/1) using GCC -O3 as a compiler: before recoding: 51.6 sec. to - generate 300 million random numbers; after recoding: 24.0 sec. for the same - (i.e., 46.5% of original time), so speed is now about 12.5 million random - number generations per second on this machine. - - According to the URL <http://www.math.keio.ac.jp/~matumoto/emt.html> - (and paraphrasing a bit in places), the Mersenne Twister is ``designed - with consideration of the flaws of various existing generators,'' has - a period of 2^19937 - 1, gives a sequence that is 623-dimensionally - equidistributed, and ``has passed many stringent tests, including the - die-hard test of G. Marsaglia and the load test of P. Hellekalek and - S. Wegenkittl.'' It is efficient in memory usage (typically using 2506 - to 5012 bytes of static data, depending on data type sizes, and the code - is quite short as well). It generates random numbers in batches of 624 - at a time, so the caching and pipelining of modern systems is exploited. - It is also divide- and mod-free. - - This library is free software; you can redistribute it and/or modify it - under the terms of the GNU Library General Public License as published by - the Free Software Foundation (either version 2 of the License or, at your - option, any later version). This library is distributed in the hope that - it will be useful, but WITHOUT ANY WARRANTY, without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See - the GNU Library General Public License for more details. You should have - received a copy of the GNU Library General Public License along with this - library; if not, write to the Free Software Foundation, Inc., 59 Temple - Place, Suite 330, Boston, MA 02111-1307, USA. - - The code as Shawn received it included the following notice: - - Copyright (C) 1997 Makoto Matsumoto and Takuji Nishimura. When - you use this, send an e-mail to <matumoto@math.keio.ac.jp> with - an appropriate reference to your work. - - It would be nice to CC: <Cokus@math.washington.edu> when you write. - - - - php_uint32 must be an unsigned integer type capable of holding at least 32 - bits; exactly 32 should be fastest, but 64 is better on an Alpha with - GCC at -O3 optimization so try your options and see what's best for you - - Melo: we should put some ifdefs here to catch those alphas... -*/ - - -#define N MT_N /* length of state vector */ -#define M (397) /* a period parameter */ -#define K (0x9908B0DFU) /* a magic constant */ -#define hiBit(u) ((u) & 0x80000000U) /* mask all but highest bit of u */ -#define loBit(u) ((u) & 0x00000001U) /* mask all but lowest bit of u */ -#define loBits(u) ((u) & 0x7FFFFFFFU) /* mask the highest bit of u */ -#define mixBits(u, v) (hiBit(u)|loBits(v)) /* move hi bit of u to hi bit of v */ - -#define MT_RAND_MAX ((long)(0x7FFFFFFF)) /* (1<<31) - 1 */ - -/* {{{ seedMT - */ -static void seedMT(php_uint32 seed BLS_DC) -{ - /* - We initialize state[0..(N-1)] via the generator - - x_new = (69069 * x_old) mod 2^32 - - from Line 15 of Table 1, p. 106, Sec. 3.3.4 of Knuth's - _The Art of Computer Programming_, Volume 2, 3rd ed. - - Notes (SJC): I do not know what the initial state requirements - of the Mersenne Twister are, but it seems this seeding generator - could be better. It achieves the maximum period for its modulus - (2^30) iff x_initial is odd (p. 20-21, Sec. 3.2.1.2, Knuth); if - x_initial can be even, you have sequences like 0, 0, 0, ...; - 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, - the next-to-lowest bit of x is always 0, - the 2nd-from-lowest bit of x alternates ... 0 1 0 1 0 1 0 1 ... , - the 3rd-from-lowest bit of x 4-cycles ... 0 1 1 0 0 1 1 0 ... , - the 4th-from-lowest bit of x has the 8-cycle ... 0 0 0 1 1 1 1 0 ... , - ... - - and if x_initial is 3 mod 4 then - - the lowest bit of x is always 1, - the next-to-lowest bit of x is always 1, - the 2nd-from-lowest bit of x alternates ... 0 1 0 1 0 1 0 1 ... , - the 3rd-from-lowest bit of x 4-cycles ... 0 0 1 1 0 0 1 1 ... , - the 4th-from-lowest bit of x has the 8-cycle ... 0 0 1 1 1 1 0 0 ... , - ... - - The generator's potency (min. s>=0 with (69069-1)^s = 0 mod 2^32) is - 16, which seems to be alright by p. 25, Sec. 3.2.1.3 of Knuth. It - also does well in the dimension 2..5 spectral tests, but it could be - better in dimension 6 (Line 15, Table 1, p. 106, Sec. 3.3.4, Knuth). - - Note that the random number user does not see the values generated - here directly since reloadMT() will always munge them first, so maybe - none of all of this matters. In fact, the seed values made here could - even be extra-special desirable if the Mersenne Twister theory says - so-- that's why the only change I made is to restrict to odd seeds. - */ - - register php_uint32 x = (seed | 1U) & 0xFFFFFFFFU, *s = BG(state); - register int j; - - for(BG(left)=0, *s++=x, j=N; --j; - *s++ = (x*=69069U) & 0xFFFFFFFFU); -} -/* }}} */ - -static php_uint32 reloadMT(BLS_D) -{ - register php_uint32 *p0=BG(state), *p2=BG(state)+2, *pM=BG(state)+M, s0, s1; - register int j; - - if(BG(left) < -1) - seedMT(4357U BLS_CC); - - BG(left)=N-1, BG(next)=BG(state)+1; - - for(s0=BG(state)[0], s1=BG(state)[1], j=N-M+1; --j; s0=s1, s1=*p2++) - *p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U); - - for(pM=BG(state), j=M; --j; s0=s1, s1=*p2++) - *p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U); - - s1=BG(state)[0], *p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U); - s1 ^= (s1 >> 11); - s1 ^= (s1 << 7) & 0x9D2C5680U; - s1 ^= (s1 << 15) & 0xEFC60000U; - return(s1 ^ (s1 >> 18)); -} - - -static inline php_uint32 randomMT(void) -{ - php_uint32 y; - BLS_FETCH(); - - if(--BG(left) < 0) - return(reloadMT(BLS_C)); - - y = *BG(next)++; - y ^= (y >> 11); - y ^= (y << 7) & 0x9D2C5680U; - y ^= (y << 15) & 0xEFC60000U; - return(y ^ (y >> 18)); -} - -/* {{{ proto void srand(int seed) - Seeds random number generator */ -PHP_FUNCTION(srand) -{ - pval **arg; - - if (ZEND_NUM_ARGS() != 1 || zend_get_parameters_ex(1, &arg) == FAILURE) { - WRONG_PARAM_COUNT; - } - convert_to_long_ex(arg); - php_srand((*arg)->value.lval); -} -/* }}} */ - -/* {{{ proto void mt_srand(int seed) - Seeds Mersenne Twister random number generator */ -PHP_FUNCTION(mt_srand) -{ - pval **arg; - BLS_FETCH(); - - if (ZEND_NUM_ARGS() != 1 || zend_get_parameters_ex(1, &arg) == FAILURE) { - WRONG_PARAM_COUNT; - } - convert_to_long_ex(arg); - seedMT((*arg)->value.lval BLS_CC); -} -/* }}} */ - -/* {{{ proto int rand([int min, int max]) - Returns a random number */ -PHP_FUNCTION(rand) -{ - pval **p_min=NULL, **p_max=NULL; - - switch (ZEND_NUM_ARGS()) { - case 0: - break; - case 2: - if (zend_get_parameters_ex(2, &p_min, &p_max)==FAILURE) { - RETURN_FALSE; - } - convert_to_long_ex(p_min); - convert_to_long_ex(p_max); - if ((*p_max)->value.lval-(*p_min)->value.lval < 0) { - php_error(E_WARNING,"rand(): Invalid range: %ld..%ld", (*p_min)->value.lval, (*p_max)->value.lval); - }else if ((*p_max)->value.lval-(*p_min)->value.lval > PHP_RAND_MAX){ - php3_error(E_WARNING,"rand(): Invalid range: %ld..%ld", (*p_min)->value.lval, (*p_max)->value.lval); - } - break; - default: - WRONG_PARAM_COUNT; - break; - } - - return_value->type = IS_LONG; - - return_value->value.lval = php_rand(); - - /* - * 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 - # artifically 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 - */ - if (p_min && p_max) { /* implement range */ - return_value->value.lval = (*p_min)->value.lval + - (int)((double)((*p_max)->value.lval - (*p_min)->value.lval + 1.0) * return_value->value.lval/(PHP_RAND_MAX+1.0)); - } -} -/* }}} */ - -/* {{{ proto int mt_rand([int min, int max]) - Returns a random number from Mersenne Twister */ -PHP_FUNCTION(mt_rand) -{ - pval **p_min=NULL, **p_max=NULL; - - switch (ZEND_NUM_ARGS()) { - case 0: - break; - case 2: - if (zend_get_parameters_ex(2, &p_min, &p_max)==FAILURE) { - RETURN_FALSE; - } - convert_to_long_ex(p_min); - convert_to_long_ex(p_max); - if ((*p_max)->value.lval-(*p_min)->value.lval <= 0) { - php_error(E_WARNING,"mt_rand(): Invalid range: %ld..%ld", (*p_min)->value.lval, (*p_max)->value.lval); - }else if ((*p_max)->value.lval-(*p_min)->value.lval > MT_RAND_MAX){ - php3_error(E_WARNING,"mt_rand(): Invalid range: %ld..%ld",(*p_min)->value.lval, (*p_max)->value.lval); - } - break; - default: - WRONG_PARAM_COUNT; - break; - } - - return_value->type = IS_LONG; - /* - * Melo: hmms.. randomMT() returns 32 random bits... - * Yet, the previous php_rand only returns 31 at most. - * So I put a right shift to loose the lsb. It *seems* - * better than clearing the msb. - * Update: - * I talked with Cokus via email and it won't ruin the algorithm - */ - return_value->value.lval = (long)(randomMT() >> 1); - - if (p_min && p_max) { /* implement range */ - return_value->value.lval = (*p_min)->value.lval + - (long)((double)((*p_max)->value.lval - (*p_min)->value.lval + 1.0) * return_value->value.lval/(MT_RAND_MAX+1.0)); - } -} -/* }}} */ - -/* {{{ proto int getrandmax(void) - Returns the maximum value a random number can have */ -PHP_FUNCTION(getrandmax) -{ - return_value->type = IS_LONG; - return_value->value.lval = PHP_RAND_MAX; -} -/* }}} */ - -/* {{{ proto int mt_getrandmax(void) - Returns the maximum value a random number from Mersenne Twister can have */ -PHP_FUNCTION(mt_getrandmax) -{ - return_value->type = IS_LONG; - /* - * Melo: it could be 2^^32 but we only use 2^^31 to maintain - * compatibility with the previous php_rand - */ - return_value->value.lval = MT_RAND_MAX; /* 2^^31 */ -} -/* }}} */ - -/* - * Local variables: - * tab-width: 4 - * c-basic-offset: 4 - * End: - * vim600: sw=4 ts=4 tw=78 fdm=marker - * vim<600: sw=4 ts=4 tw=78 - */ |