/* GLIB - Library of useful routines for C programming
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser 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.
*/
/* Originally developed and coded by Makoto Matsumoto and Takuji
* Nishimura. Please mail <matumoto@math.keio.ac.jp>, if you're using
* code from this file in your own programs or libraries.
* Further information on the Mersenne Twister can be found at
* http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
* This code was adapted to glib by Sebastian Wilhelmi.
*/
/*
* Modified by the GLib Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GLib Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GLib at ftp://ftp.gtk.org/pub/gtk/.
*/
/*
* MT safe
*/
#include "config.h"
#include <math.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "grand.h"
#include "genviron.h"
#include "gmain.h"
#include "gmem.h"
#include "gtestutils.h"
#include "gthread.h"
#ifdef G_OS_WIN32
#include <process.h> /* For getpid() */
#endif
/**
* SECTION:random_numbers
* @title: Random Numbers
* @short_description: pseudo-random number generator
*
* The following functions allow you to use a portable, fast and good
* pseudo-random number generator (PRNG). It uses the Mersenne Twister
* PRNG, which was originally developed by Makoto Matsumoto and Takuji
* Nishimura. Further information can be found at
* <ulink url="http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html">
* http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html</ulink>.
*
* If you just need a random number, you simply call the
* <function>g_random_*</function> functions, which will create a
* globally used #GRand and use the according
* <function>g_rand_*</function> functions internally. Whenever you
* need a stream of reproducible random numbers, you better create a
* #GRand yourself and use the <function>g_rand_*</function> functions
* directly, which will also be slightly faster. Initializing a #GRand
* with a certain seed will produce exactly the same series of random
* numbers on all platforms. This can thus be used as a seed for e.g.
* games.
*
* The <function>g_rand*_range</function> functions will return high
* quality equally distributed random numbers, whereas for example the
* <literal>(g_random_int()%max)</literal> approach often
* doesn't yield equally distributed numbers.
*
* GLib changed the seeding algorithm for the pseudo-random number
* generator Mersenne Twister, as used by
* <structname>GRand</structname> and <structname>GRandom</structname>.
* This was necessary, because some seeds would yield very bad
* pseudo-random streams. Also the pseudo-random integers generated by
* <function>g_rand*_int_range()</function> will have a slightly better
* equal distribution with the new version of GLib.
*
* The original seeding and generation algorithms, as found in GLib
* 2.0.x, can be used instead of the new ones by setting the
* environment variable <envar>G_RANDOM_VERSION</envar> to the value of
* '2.0'. Use the GLib-2.0 algorithms only if you have sequences of
* numbers generated with Glib-2.0 that you need to reproduce exactly.
**/
/**
* GRand:
*
* The #GRand struct is an opaque data structure. It should only be
* accessed through the <function>g_rand_*</function> functions.
**/
G_LOCK_DEFINE_STATIC (global_random);
static GRand* global_random = NULL;
/* Period parameters */
#define N 624
#define M 397
#define MATRIX_A 0x9908b0df /* constant vector a */
#define UPPER_MASK 0x80000000 /* most significant w-r bits */
#define LOWER_MASK 0x7fffffff /* least significant r bits */
/* Tempering parameters */
#define TEMPERING_MASK_B 0x9d2c5680
#define TEMPERING_MASK_C 0xefc60000
#define TEMPERING_SHIFT_U(y) (y >> 11)
#define TEMPERING_SHIFT_S(y) (y << 7)
#define TEMPERING_SHIFT_T(y) (y << 15)
#define TEMPERING_SHIFT_L(y) (y >> 18)
static guint
get_random_version (void)
{
static gsize initialized = FALSE;
static guint random_version;
if (g_once_init_enter (&initialized))
{
const gchar *version_string = g_getenv ("G_RANDOM_VERSION");
if (!version_string || version_string[0] == '\000' ||
strcmp (version_string, "2.2") == 0)
random_version = 22;
else if (strcmp (version_string, "2.0") == 0)
random_version = 20;
else
{
g_warning ("Unknown G_RANDOM_VERSION \"%s\". Using version 2.2.",
version_string);
random_version = 22;
}
g_once_init_leave (&initialized, TRUE);
}
return random_version;
}
struct _GRand
{
guint32 mt[N]; /* the array for the state vector */
guint mti;
};
/**
* g_rand_new_with_seed:
* @seed: a value to initialize the random number generator.
*
* Creates a new random number generator initialized with @seed.
*
* Return value: the new #GRand.
**/
GRand*
g_rand_new_with_seed (guint32 seed)
{
GRand *rand = g_new0 (GRand, 1);
g_rand_set_seed (rand, seed);
return rand;
}
/**
* g_rand_new_with_seed_array:
* @seed: an array of seeds to initialize the random number generator.
* @seed_length: an array of seeds to initialize the random number generator.
*
* Creates a new random number generator initialized with @seed.
*
* Return value: the new #GRand.
*
* Since: 2.4
**/
GRand*
g_rand_new_with_seed_array (const guint32 *seed, guint seed_length)
{
GRand *rand = g_new0 (GRand, 1);
g_rand_set_seed_array (rand, seed, seed_length);
return rand;
}
/**
* g_rand_new:
*
* Creates a new random number generator initialized with a seed taken
* either from <filename>/dev/urandom</filename> (if existing) or from
* the current time (as a fallback).
*
* Return value: the new #GRand.
**/
GRand*
g_rand_new (void)
{
guint32 seed[4];
GTimeVal now;
#ifdef G_OS_UNIX
static gboolean dev_urandom_exists = TRUE;
if (dev_urandom_exists)
{
FILE* dev_urandom;
do
{
dev_urandom = fopen("/dev/urandom", "rb");
}
while G_UNLIKELY (dev_urandom == NULL && errno == EINTR);
if (dev_urandom)
{
int r;
setvbuf (dev_urandom, NULL, _IONBF, 0);
do
{
errno = 0;
r = fread (seed, sizeof (seed), 1, dev_urandom);
}
while G_UNLIKELY (errno == EINTR);
if (r != 1)
dev_urandom_exists = FALSE;
fclose (dev_urandom);
}
else
dev_urandom_exists = FALSE;
}
#else
static gboolean dev_urandom_exists = FALSE;
#endif
if (!dev_urandom_exists)
{
g_get_current_time (&now);
seed[0] = now.tv_sec;
seed[1] = now.tv_usec;
seed[2] = getpid ();
#ifdef G_OS_UNIX
seed[3] = getppid ();
#else
seed[3] = 0;
#endif
}
return g_rand_new_with_seed_array (seed, 4);
}
/**
* g_rand_free:
* @rand_: a #GRand.
*
* Frees the memory allocated for the #GRand.
**/
void
g_rand_free (GRand* rand)
{
g_return_if_fail (rand != NULL);
g_free (rand);
}
/**
* g_rand_copy:
* @rand_: a #GRand.
*
* Copies a #GRand into a new one with the same exact state as before.
* This way you can take a snapshot of the random number generator for
* replaying later.
*
* Return value: the new #GRand.
*
* Since: 2.4
**/
GRand *
g_rand_copy (GRand* rand)
{
GRand* new_rand;
g_return_val_if_fail (rand != NULL, NULL);
new_rand = g_new0 (GRand, 1);
memcpy (new_rand, rand, sizeof (GRand));
return new_rand;
}
/**
* g_rand_set_seed:
* @rand_: a #GRand.
* @seed: a value to reinitialize the random number generator.
*
* Sets the seed for the random number generator #GRand to @seed.
**/
void
g_rand_set_seed (GRand* rand, guint32 seed)
{
g_return_if_fail (rand != NULL);
switch (get_random_version ())
{
case 20:
/* setting initial seeds to mt[N] using */
/* the generator Line 25 of Table 1 in */
/* [KNUTH 1981, The Art of Computer Programming */
/* Vol. 2 (2nd Ed.), pp102] */
if (seed == 0) /* This would make the PRNG produce only zeros */
seed = 0x6b842128; /* Just set it to another number */
rand->mt[0]= seed;
for (rand->mti=1; rand->mti<N; rand->mti++)
rand->mt[rand->mti] = (69069 * rand->mt[rand->mti-1]);
break;
case 22:
/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
/* In the previous version (see above), MSBs of the */
/* seed affect only MSBs of the array mt[]. */
rand->mt[0]= seed;
for (rand->mti=1; rand->mti<N; rand->mti++)
rand->mt[rand->mti] = 1812433253UL *
(rand->mt[rand->mti-1] ^ (rand->mt[rand->mti-1] >> 30)) + rand->mti;
break;
default:
g_assert_not_reached ();
}
}
/**
* g_rand_set_seed_array:
* @rand_: a #GRand.
* @seed: array to initialize with
* @seed_length: length of array
*
* Initializes the random number generator by an array of
* longs. Array can be of arbitrary size, though only the
* first 624 values are taken. This function is useful
* if you have many low entropy seeds, or if you require more then
* 32bits of actual entropy for your application.
*
* Since: 2.4
**/
void
g_rand_set_seed_array (GRand* rand, const guint32 *seed, guint seed_length)
{
int i, j, k;
g_return_if_fail (rand != NULL);
g_return_if_fail (seed_length >= 1);
g_rand_set_seed (rand, 19650218UL);
i=1; j=0;
k = (N>seed_length ? N : seed_length);
for (; k; k--)
{
rand->mt[i] = (rand->mt[i] ^
((rand->mt[i-1] ^ (rand->mt[i-1] >> 30)) * 1664525UL))
+ seed[j] + j; /* non linear */
rand->mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
i++; j++;
if (i>=N)
{
rand->mt[0] = rand->mt[N-1];
i=1;
}
if (j>=seed_length)
j=0;
}
for (k=N-1; k; k--)
{
rand->mt[i] = (rand->mt[i] ^
((rand->mt[i-1] ^ (rand->mt[i-1] >> 30)) * 1566083941UL))
- i; /* non linear */
rand->mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
i++;
if (i>=N)
{
rand->mt[0] = rand->mt[N-1];
i=1;
}
}
rand->mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */
}
/**
* g_rand_boolean:
* @rand_: a #GRand.
* @Returns: a random #gboolean.
*
* Returns a random #gboolean from @rand_. This corresponds to a
* unbiased coin toss.
**/
/**
* g_rand_int:
* @rand_: a #GRand.
*
* Returns the next random #guint32 from @rand_ equally distributed over
* the range [0..2^32-1].
*
* Return value: A random number.
**/
guint32
g_rand_int (GRand* rand)
{
guint32 y;
static const guint32 mag01[2]={0x0, MATRIX_A};
/* mag01[x] = x * MATRIX_A for x=0,1 */
g_return_val_if_fail (rand != NULL, 0);
if (rand->mti >= N) { /* generate N words at one time */
int kk;
for (kk=0;kk<N-M;kk++) {
y = (rand->mt[kk]&UPPER_MASK)|(rand->mt[kk+1]&LOWER_MASK);
rand->mt[kk] = rand->mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1];
}
for (;kk<N-1;kk++) {
y = (rand->mt[kk]&UPPER_MASK)|(rand->mt[kk+1]&LOWER_MASK);
rand->mt[kk] = rand->mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1];
}
y = (rand->mt[N-1]&UPPER_MASK)|(rand->mt[0]&LOWER_MASK);
rand->mt[N-1] = rand->mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1];
rand->mti = 0;
}
y = rand->mt[rand->mti++];
y ^= TEMPERING_SHIFT_U(y);
y ^= TEMPERING_SHIFT_S(y) & TEMPERING_MASK_B;
y ^= TEMPERING_SHIFT_T(y) & TEMPERING_MASK_C;
y ^= TEMPERING_SHIFT_L(y);
return y;
}
/* transform [0..2^32] -> [0..1] */
#define G_RAND_DOUBLE_TRANSFORM 2.3283064365386962890625e-10
/**
* g_rand_int_range:
* @rand_: a #GRand.
* @begin: lower closed bound of the interval.
* @end: upper open bound of the interval.
*
* Returns the next random #gint32 from @rand_ equally distributed over
* the range [@begin..@end-1].
*
* Return value: A random number.
**/
gint32
g_rand_int_range (GRand* rand, gint32 begin, gint32 end)
{
guint32 dist = end - begin;
guint32 random;
g_return_val_if_fail (rand != NULL, begin);
g_return_val_if_fail (end > begin, begin);
switch (get_random_version ())
{
case 20:
if (dist <= 0x10000L) /* 2^16 */
{
/* This method, which only calls g_rand_int once is only good
* for (end - begin) <= 2^16, because we only have 32 bits set
* from the one call to g_rand_int (). */
/* we are using (trans + trans * trans), because g_rand_int only
* covers [0..2^32-1] and thus g_rand_int * trans only covers
* [0..1-2^-32], but the biggest double < 1 is 1-2^-52.
*/
gdouble double_rand = g_rand_int (rand) *
(G_RAND_DOUBLE_TRANSFORM +
G_RAND_DOUBLE_TRANSFORM * G_RAND_DOUBLE_TRANSFORM);
random = (gint32) (double_rand * dist);
}
else
{
/* Now we use g_rand_double_range (), which will set 52 bits for
us, so that it is safe to round and still get a decent
distribution */
random = (gint32) g_rand_double_range (rand, 0, dist);
}
break;
case 22:
if (dist == 0)
random = 0;
else
{
/* maxvalue is set to the predecessor of the greatest
* multiple of dist less or equal 2^32. */
guint32 maxvalue;
if (dist <= 0x80000000u) /* 2^31 */
{
/* maxvalue = 2^32 - 1 - (2^32 % dist) */
guint32 leftover = (0x80000000u % dist) * 2;
if (leftover >= dist) leftover -= dist;
maxvalue = 0xffffffffu - leftover;
}
else
maxvalue = dist - 1;
do
random = g_rand_int (rand);
while (random > maxvalue);
random %= dist;
}
break;
default:
random = 0; /* Quiet GCC */
g_assert_not_reached ();
}
return begin + random;
}
/**
* g_rand_double:
* @rand_: a #GRand.
*
* Returns the next random #gdouble from @rand_ equally distributed over
* the range [0..1).
*
* Return value: A random number.
**/
gdouble
g_rand_double (GRand* rand)
{
/* We set all 52 bits after the point for this, not only the first
32. Thats why we need two calls to g_rand_int */
gdouble retval = g_rand_int (rand) * G_RAND_DOUBLE_TRANSFORM;
retval = (retval + g_rand_int (rand)) * G_RAND_DOUBLE_TRANSFORM;
/* The following might happen due to very bad rounding luck, but
* actually this should be more than rare, we just try again then */
if (retval >= 1.0)
return g_rand_double (rand);
return retval;
}
/**
* g_rand_double_range:
* @rand_: a #GRand.
* @begin: lower closed bound of the interval.
* @end: upper open bound of the interval.
*
* Returns the next random #gdouble from @rand_ equally distributed over
* the range [@begin..@end).
*
* Return value: A random number.
**/
gdouble
g_rand_double_range (GRand* rand, gdouble begin, gdouble end)
{
gdouble r;
r = g_rand_double (rand);
return r * end - (r - 1) * begin;
}
/**
* g_random_boolean:
* @Returns: a random #gboolean.
*
* Returns a random #gboolean. This corresponds to a unbiased coin toss.
**/
/**
* g_random_int:
*
* Return a random #guint32 equally distributed over the range
* [0..2^32-1].
*
* Return value: A random number.
**/
guint32
g_random_int (void)
{
guint32 result;
G_LOCK (global_random);
if (!global_random)
global_random = g_rand_new ();
result = g_rand_int (global_random);
G_UNLOCK (global_random);
return result;
}
/**
* g_random_int_range:
* @begin: lower closed bound of the interval.
* @end: upper open bound of the interval.
*
* Returns a random #gint32 equally distributed over the range
* [@begin..@end-1].
*
* Return value: A random number.
**/
gint32
g_random_int_range (gint32 begin, gint32 end)
{
gint32 result;
G_LOCK (global_random);
if (!global_random)
global_random = g_rand_new ();
result = g_rand_int_range (global_random, begin, end);
G_UNLOCK (global_random);
return result;
}
/**
* g_random_double:
*
* Returns a random #gdouble equally distributed over the range [0..1).
*
* Return value: A random number.
**/
gdouble
g_random_double (void)
{
double result;
G_LOCK (global_random);
if (!global_random)
global_random = g_rand_new ();
result = g_rand_double (global_random);
G_UNLOCK (global_random);
return result;
}
/**
* g_random_double_range:
* @begin: lower closed bound of the interval.
* @end: upper open bound of the interval.
*
* Returns a random #gdouble equally distributed over the range [@begin..@end).
*
* Return value: A random number.
**/
gdouble
g_random_double_range (gdouble begin, gdouble end)
{
double result;
G_LOCK (global_random);
if (!global_random)
global_random = g_rand_new ();
result = g_rand_double_range (global_random, begin, end);
G_UNLOCK (global_random);
return result;
}
/**
* g_random_set_seed:
* @seed: a value to reinitialize the global random number generator.
*
* Sets the seed for the global random number generator, which is used
* by the <function>g_random_*</function> functions, to @seed.
**/
void
g_random_set_seed (guint32 seed)
{
G_LOCK (global_random);
if (!global_random)
global_random = g_rand_new_with_seed (seed);
else
g_rand_set_seed (global_random, seed);
G_UNLOCK (global_random);
}