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344 lines
12 KiB
C
344 lines
12 KiB
C
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/*
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+----------------------------------------------------------------------+
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| PHP HTML Embedded Scripting Language Version 3.0 |
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+----------------------------------------------------------------------+
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| Copyright (c) 1997,1998 PHP Development Team (See Credits file) |
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+----------------------------------------------------------------------+
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| This program is free software; you can redistribute it and/or modify |
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| it under the terms of one of the following licenses: |
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| |
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| A) the GNU General Public License as published by the Free Software |
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| Foundation; either version 2 of the License, or (at your option) |
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| any later version. |
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| |
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| B) the PHP License as published by the PHP Development Team and |
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| included in the distribution in the file: LICENSE |
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| |
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| This program is distributed in the hope that it will be useful, |
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| but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| GNU General Public License for more details. |
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| |
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| You should have received a copy of both licenses referred to here. |
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| If you did not, or have any questions about PHP licensing, please |
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| contact core@php.net. |
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+----------------------------------------------------------------------+
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| Authors: Rasmus Lerdorf <rasmus@lerdorf.on.ca> |
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| Zeev Suraski <zeev@zend.com |
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| Pedro Melo <melo@ip.pt> |
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| |
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| Based on code from: 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 "phpmath.h"
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#ifndef RAND_MAX
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#define RAND_MAX (1<<15)
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#endif
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/*
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This is the ``Mersenne Twister'' random number generator MT19937, which
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generates pseudorandom integers uniformly distributed in 0..(2^32 - 1)
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starting from any odd seed in 0..(2^32 - 1). This version is a recode
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by Shawn Cokus (Cokus@math.washington.edu) on March 8, 1998 of a version by
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Takuji Nishimura (who had suggestions from Topher Cooper and Marc Rieffel in
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July-August 1997).
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Effectiveness of the recoding (on Goedel2.math.washington.edu, a DEC Alpha
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running OSF/1) using GCC -O3 as a compiler: before recoding: 51.6 sec. to
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generate 300 million random numbers; after recoding: 24.0 sec. for the same
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(i.e., 46.5% of original time), so speed is now about 12.5 million random
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number generations per second on this machine.
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According to the URL <http://www.math.keio.ac.jp/~matumoto/emt.html>
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(and paraphrasing a bit in places), the Mersenne Twister is ``designed
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with consideration of the flaws of various existing generators,'' has
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a period of 2^19937 - 1, gives a sequence that is 623-dimensionally
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equidistributed, and ``has passed many stringent tests, including the
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die-hard test of G. Marsaglia and the load test of P. Hellekalek and
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S. Wegenkittl.'' It is efficient in memory usage (typically using 2506
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to 5012 bytes of static data, depending on data type sizes, and the code
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is quite short as well). It generates random numbers in batches of 624
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at a time, so the caching and pipelining of modern systems is exploited.
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It is also divide- and mod-free.
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This library is free software; you can redistribute it and/or modify it
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under the terms of the GNU Library General Public License as published by
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the Free Software Foundation (either version 2 of the License or, at your
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option, any later version). This library is distributed in the hope that
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it will be useful, but WITHOUT ANY WARRANTY, without even the implied
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warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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the GNU Library General Public License for more details. You should have
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received a copy of the GNU Library General Public License along with this
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library; if not, write to the Free Software Foundation, Inc., 59 Temple
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Place, Suite 330, Boston, MA 02111-1307, USA.
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The code as Shawn received it included the following notice:
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Copyright (C) 1997 Makoto Matsumoto and Takuji Nishimura. When
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you use this, send an e-mail to <matumoto@math.keio.ac.jp> with
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an appropriate reference to your work.
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It would be nice to CC: <Cokus@math.washington.edu> when you write.
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uint32 must be an unsigned integer type capable of holding at least 32
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bits; exactly 32 should be fastest, but 64 is better on an Alpha with
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GCC at -O3 optimization so try your options and see what's best for you
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Melo: we should put some ifdefs here to catch those alphas...
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*/
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typedef unsigned int uint32;
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#define N (624) /* length of state vector */
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#define M (397) /* a period parameter */
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#define K (0x9908B0DFU) /* a magic constant */
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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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static uint32 state[N+1]; /* state vector + 1 extra to not violate ANSI C */
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static uint32 *next; /* next random value is computed from here */
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static int left = -1; /* can *next++ this many times before reloading */
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static void seedMT(uint32 seed)
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{
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/*
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We initialize state[0..(N-1)] via the generator
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x_new = (69069 * x_old) mod 2^32
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from Line 15 of Table 1, p. 106, Sec. 3.3.4 of Knuth's
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_The Art of Computer Programming_, Volume 2, 3rd ed.
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Notes (SJC): I do not know what the initial state requirements
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of the Mersenne Twister are, but it seems this seeding generator
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could be better. It achieves the maximum period for its modulus
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(2^30) iff x_initial is odd (p. 20-21, Sec. 3.2.1.2, Knuth); if
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x_initial can be even, you have sequences like 0, 0, 0, ...;
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2^31, 2^31, 2^31, ...; 2^30, 2^30, 2^30, ...; 2^29, 2^29 + 2^31,
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2^29, 2^29 + 2^31, ..., etc. so I force seed to be odd below.
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Even if x_initial is odd, if x_initial is 1 mod 4 then
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the lowest bit of x is always 1,
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the next-to-lowest bit of x is always 0,
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the 2nd-from-lowest bit of x alternates ... 0 1 0 1 0 1 0 1 ... ,
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the 3rd-from-lowest bit of x 4-cycles ... 0 1 1 0 0 1 1 0 ... ,
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the 4th-from-lowest bit of x has the 8-cycle ... 0 0 0 1 1 1 1 0 ... ,
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...
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and if x_initial is 3 mod 4 then
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the lowest bit of x is always 1,
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the next-to-lowest bit of x is always 1,
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the 2nd-from-lowest bit of x alternates ... 0 1 0 1 0 1 0 1 ... ,
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the 3rd-from-lowest bit of x 4-cycles ... 0 0 1 1 0 0 1 1 ... ,
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the 4th-from-lowest bit of x has the 8-cycle ... 0 0 1 1 1 1 0 0 ... ,
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...
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The generator's potency (min. s>=0 with (69069-1)^s = 0 mod 2^32) is
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16, which seems to be alright by p. 25, Sec. 3.2.1.3 of Knuth. It
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also does well in the dimension 2..5 spectral tests, but it could be
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better in dimension 6 (Line 15, Table 1, p. 106, Sec. 3.3.4, Knuth).
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Note that the random number user does not see the values generated
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here directly since reloadMT() will always munge them first, so maybe
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none of all of this matters. In fact, the seed values made here could
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even be extra-special desirable if the Mersenne Twister theory says
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so-- that's why the only change I made is to restrict to odd seeds.
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*/
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register uint32 x = (seed | 1U) & 0xFFFFFFFFU, *s = state;
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register int j;
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for(left=0, *s++=x, j=N; --j;
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*s++ = (x*=69069U) & 0xFFFFFFFFU);
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}
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static uint32 reloadMT(void)
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{
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register uint32 *p0=state, *p2=state+2, *pM=state+M, s0, s1;
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register int j;
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if(left < -1)
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seedMT(4357U);
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left=N-1, next=state+1;
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for(s0=state[0], s1=state[1], j=N-M+1; --j; s0=s1, s1=*p2++)
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*p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
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for(pM=state, j=M; --j; s0=s1, s1=*p2++)
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*p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
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s1=state[0], *p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
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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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static inline uint32 randomMT(void)
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{
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uint32 y;
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if(--left < 0)
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return(reloadMT());
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y = *next++;
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y ^= (y >> 11);
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y ^= (y << 7) & 0x9D2C5680U;
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y ^= (y << 15) & 0xEFC60000U;
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return(y ^ (y >> 18));
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}
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#if HAVE_LRAND48
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#define PHP_RAND_MAX 2147483647
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#else
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#define PHP_RAND_MAX RAND_MAX
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#endif
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void php3_srand(INTERNAL_FUNCTION_PARAMETERS)
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{
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pval *arg;
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if (ARG_COUNT(ht) != 1 || getParameters(ht, 1, &arg) == FAILURE) {
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WRONG_PARAM_COUNT;
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}
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convert_to_long(arg);
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#ifdef HAVE_SRAND48
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srand48((unsigned int) arg->value.lval);
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#else
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#ifdef HAVE_SRANDOM
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srandom((unsigned int) arg->value.lval);
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#else
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srand((unsigned int) arg->value.lval);
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#endif
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#endif
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}
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void php3_mt_srand(INTERNAL_FUNCTION_PARAMETERS)
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{
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pval *arg;
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if (ARG_COUNT(ht) != 1 || getParameters(ht, 1, &arg) == FAILURE) {
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WRONG_PARAM_COUNT;
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}
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convert_to_long(arg);
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seedMT(arg->value.lval);
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}
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void php3_rand(INTERNAL_FUNCTION_PARAMETERS)
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{
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pval *p_min=NULL, *p_max=NULL;
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switch (ARG_COUNT(ht)) {
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case 0:
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break;
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case 2:
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if (getParameters(ht, 2, &p_min, &p_max)==FAILURE) {
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RETURN_FALSE;
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}
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convert_to_long(p_min);
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convert_to_long(p_max);
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if (p_max->value.lval-p_min->value.lval <= 0) {
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php3_error(E_WARNING,"rand(): Invalid range: %ld..%ld", p_min->value.lval, p_max->value.lval);
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}
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break;
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default:
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WRONG_PARAM_COUNT;
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break;
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}
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return_value->type = IS_LONG;
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#ifdef HAVE_LRAND48
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return_value->value.lval = lrand48();
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#else
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#ifdef HAVE_RANDOM
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return_value->value.lval = random();
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#else
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return_value->value.lval = rand();
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#endif
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#endif
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if (p_min && p_max) { /* implement range */
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return_value->value.lval = p_min->value.lval +
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(int)((double)p_max->value.lval * return_value->value.lval/(PHP_RAND_MAX+(double)p_min->value.lval));
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}
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}
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void php3_mt_rand(INTERNAL_FUNCTION_PARAMETERS)
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{
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pval *p_min=NULL, *p_max=NULL;
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switch (ARG_COUNT(ht)) {
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case 0:
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break;
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case 2:
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if (getParameters(ht, 2, &p_min, &p_max)==FAILURE) {
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RETURN_FALSE;
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}
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convert_to_long(p_min);
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convert_to_long(p_max);
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if (p_max->value.lval-p_min->value.lval <= 0) {
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php3_error(E_WARNING,"mtrand(): Invalid range: %ld..%ld", p_min->value.lval, p_max->value.lval);
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}
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break;
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default:
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WRONG_PARAM_COUNT;
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break;
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}
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return_value->type = IS_LONG;
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/*
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* Melo: hmms.. randomMT() returns 32 random bits...
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* Yet, the previous php3_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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return_value->value.lval = (long)(randomMT() >> 1);
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if (p_min && p_max) { /* implement range */
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return_value->value.lval = p_min->value.lval +
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(int)((double)p_max->value.lval * return_value->value.lval/(PHP_RAND_MAX+(double)p_min->value.lval));
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}
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}
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void php3_getrandmax(INTERNAL_FUNCTION_PARAMETERS)
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{
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return_value->type = IS_LONG;
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return_value->value.lval = PHP_RAND_MAX;
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}
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void php3_mt_getrandmax(INTERNAL_FUNCTION_PARAMETERS)
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{
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return_value->type = IS_LONG;
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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 php3_rand
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*/
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return_value->value.lval = 2147483647; /* 2^^31 */
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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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*/
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