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Diffstat (limited to 'ext/standard/rand.c')
| -rw-r--r-- | ext/standard/rand.c | 343 |
1 files changed, 343 insertions, 0 deletions
diff --git a/ext/standard/rand.c b/ext/standard/rand.c new file mode 100644 index 0000000000..e117833296 --- /dev/null +++ b/ext/standard/rand.c @@ -0,0 +1,343 @@ +/* + +----------------------------------------------------------------------+ + | PHP HTML Embedded Scripting Language Version 3.0 | + +----------------------------------------------------------------------+ + | Copyright (c) 1997,1998 PHP Development Team (See Credits file) | + +----------------------------------------------------------------------+ + | This program is free software; you can redistribute it and/or modify | + | it under the terms of one of the following licenses: | + | | + | A) the GNU General Public License as published by the Free Software | + | Foundation; either version 2 of the License, or (at your option) | + | any later version. | + | | + | B) the PHP License as published by the PHP Development Team and | + | included in the distribution in the file: LICENSE | + | | + | This program 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 General Public License for more details. | + | | + | You should have received a copy of both licenses referred to here. | + | If you did not, or have any questions about PHP licensing, please | + | contact core@php.net. | + +----------------------------------------------------------------------+ + | 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 "phpmath.h" + +#ifndef RAND_MAX +#define RAND_MAX (1<<15) + +#endif + +/* + 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. + + + + 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... +*/ + +typedef unsigned int uint32; + +#define N (624) /* 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 */ + +static uint32 state[N+1]; /* state vector + 1 extra to not violate ANSI C */ +static uint32 *next; /* next random value is computed from here */ +static int left = -1; /* can *next++ this many times before reloading */ + + +static void seedMT(uint32 seed) +{ + /* + 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 uint32 x = (seed | 1U) & 0xFFFFFFFFU, *s = state; + register int j; + + for(left=0, *s++=x, j=N; --j; + *s++ = (x*=69069U) & 0xFFFFFFFFU); +} + + +static uint32 reloadMT(void) +{ + register uint32 *p0=state, *p2=state+2, *pM=state+M, s0, s1; + register int j; + + if(left < -1) + seedMT(4357U); + + left=N-1, next=state+1; + + for(s0=state[0], s1=state[1], j=N-M+1; --j; s0=s1, s1=*p2++) + *p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U); + + for(pM=state, j=M; --j; s0=s1, s1=*p2++) + *p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U); + + s1=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 uint32 randomMT(void) +{ + uint32 y; + + if(--left < 0) + return(reloadMT()); + + y = *next++; + y ^= (y >> 11); + y ^= (y << 7) & 0x9D2C5680U; + y ^= (y << 15) & 0xEFC60000U; + return(y ^ (y >> 18)); +} + + +#if HAVE_LRAND48 +#define PHP_RAND_MAX 2147483647 +#else +#define PHP_RAND_MAX RAND_MAX +#endif + +void php3_srand(INTERNAL_FUNCTION_PARAMETERS) +{ + pval *arg; + + if (ARG_COUNT(ht) != 1 || getParameters(ht, 1, &arg) == FAILURE) { + WRONG_PARAM_COUNT; + } + convert_to_long(arg); +#ifdef HAVE_SRAND48 + srand48((unsigned int) arg->value.lval); +#else +#ifdef HAVE_SRANDOM + srandom((unsigned int) arg->value.lval); +#else + srand((unsigned int) arg->value.lval); +#endif +#endif +} + +void php3_mt_srand(INTERNAL_FUNCTION_PARAMETERS) +{ + pval *arg; + if (ARG_COUNT(ht) != 1 || getParameters(ht, 1, &arg) == FAILURE) { + WRONG_PARAM_COUNT; + } + convert_to_long(arg); + seedMT(arg->value.lval); +} + +void php3_rand(INTERNAL_FUNCTION_PARAMETERS) +{ + pval *p_min=NULL, *p_max=NULL; + + switch (ARG_COUNT(ht)) { + case 0: + break; + case 2: + if (getParameters(ht, 2, &p_min, &p_max)==FAILURE) { + RETURN_FALSE; + } + convert_to_long(p_min); + convert_to_long(p_max); + if (p_max->value.lval-p_min->value.lval <= 0) { + 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; +#ifdef HAVE_LRAND48 + return_value->value.lval = lrand48(); +#else +#ifdef HAVE_RANDOM + return_value->value.lval = random(); +#else + return_value->value.lval = rand(); +#endif +#endif + + if (p_min && p_max) { /* implement range */ + return_value->value.lval = p_min->value.lval + + (int)((double)p_max->value.lval * return_value->value.lval/(PHP_RAND_MAX+(double)p_min->value.lval)); + } +} + +void php3_mt_rand(INTERNAL_FUNCTION_PARAMETERS) +{ + pval *p_min=NULL, *p_max=NULL; + + switch (ARG_COUNT(ht)) { + case 0: + break; + case 2: + if (getParameters(ht, 2, &p_min, &p_max)==FAILURE) { + RETURN_FALSE; + } + convert_to_long(p_min); + convert_to_long(p_max); + if (p_max->value.lval-p_min->value.lval <= 0) { + php3_error(E_WARNING,"mtrand(): 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 php3_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 + + (int)((double)p_max->value.lval * return_value->value.lval/(PHP_RAND_MAX+(double)p_min->value.lval)); + } +} + +void php3_getrandmax(INTERNAL_FUNCTION_PARAMETERS) +{ + return_value->type = IS_LONG; + return_value->value.lval = PHP_RAND_MAX; +} + +void php3_mt_getrandmax(INTERNAL_FUNCTION_PARAMETERS) +{ + return_value->type = IS_LONG; + /* + * Melo: it could be 2^^32 but we only use 2^^31 to maintain + * compatibility with the previous php3_rand + */ + return_value->value.lval = 2147483647; /* 2^^31 */ +} + +/* + * Local variables: + * tab-width: 4 + * c-basic-offset: 4 + * End: + */ |