/* 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.keio.ac.jp/~matumoto/emt.html
* This code was adapted to glib by Sebastian Wilhelmi <wilhelmi@ira.uka.de>.
*/
/*
* 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 <glib.h>
#include <math.h>
#include <stdio.h>
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)
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:
*
* Creates a new random number generator initialized with a seed taken
* either from /dev/urandom (if existing) or from the current time (as
* a fallback).
*
* Return value: the new #GRand.
**/
GRand*
g_rand_new (void)
{
guint32 seed;
GTimeVal now;
static gboolean dev_urandom_exists = TRUE;
if (dev_urandom_exists)
{
FILE* dev_urandom = fopen("/dev/urandom", "rb");
if (dev_urandom)
{
if (fread (&seed, sizeof (seed), 1, dev_urandom) != 1)
dev_urandom_exists = FALSE;
fclose (dev_urandom);
}
else
dev_urandom_exists = FALSE;
}
if (!dev_urandom_exists)
{
g_get_current_time (&now);
seed = now.tv_sec ^ now.tv_usec;
}
return g_rand_new_with_seed (seed);
}
/**
* 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_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);
/* 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 procude only zeros */
seed = 0x6b842128; /* Just set it to another number */
rand->mt[0]= seed & 0xffffffff;
for (rand->mti=1; rand->mti<N; rand->mti++)
rand->mt[rand->mti] = (69069 * rand->mt[rand->mti-1]) & 0xffffffff;
}
/**
* g_rand_int:
* @rand: a #GRand.
*
* Return the next random #guint32 from @rand equaly 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.
*
* Return the next random #gint32 from @rand equaly 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);
/* All tricks doing modulo calculations do not have a perfect
* distribution -> We must use the slower way through gdouble for
* maximal quality. */
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);
}
return begin + random;
}
/**
* g_rand_double:
* @rand: a #GRand.
*
* Return the next random #gdouble from @rand equaly 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.
*
* Return the next random #gdouble from @rand equaly distributed over
* the range [@begin..@end).
*
* Return value: A random number.
**/
gdouble
g_rand_double_range (GRand* rand, gdouble begin, gdouble end)
{
return g_rand_double (rand) * (end - begin) + begin;
}
/**
* g_random_int:
*
* Return a random #guint32 equaly 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.
*
* Return a random #gint32 equaly 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:
*
* Return a random #gdouble equaly 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.
*
* Return a random #gdouble equaly 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 te g_random_* 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);
}