/* 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;
};
GRand*
g_rand_new_with_seed (guint32 seed)
{
GRand *rand = g_new0 (GRand, 1);
g_rand_set_seed (rand, seed);
return rand;
}
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);
}
void
g_rand_free (GRand* rand)
{
g_return_if_fail (rand != NULL);
g_free (rand);
}
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;
}
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;
}
gint32
g_rand_int_range (GRand* rand, gint32 min, gint32 max)
{
guint32 dist = max - min;
guint32 random;
g_return_val_if_fail (rand != NULL, min);
g_return_val_if_fail (max > min, min);
if (dist <= 0x10000L) /* 2^16 */
{
/* All tricks doing modulo calculations do not have a good
distribution -> We must use this slower method for maximal
quality, but this method is only good for (max - min) <= 2^16 */
random = (gint32) g_rand_double_range (rand, 0, dist);
/* we'd rather use the following, if -lm is allowed later on:
random = (gint32) floor (g_rand_double_range (rand, 0, dist)); */
}
else
{
/* Now it's harder to make it right. We calculate the smallest m,
such that dist < 2 ^ m, then we calculate a random number in
[1..2^32-1] and rightshift it by 32 - m. Then we test, if it
is smaller than dist and if not, get a new number and so
forth until we get a number smaller than dist. We just return
this. */
guint32 border = 0x20000L; /* 2^17 */
guint right_shift = 15; /* 32 - 17 */
if (dist >= 0x80000000) /* in the case of dist > 2^31 our loop
below will be infinite */
{
right_shift = 0;
}
else
{
while (dist >= border)
{
border <<= 1;
right_shift--;
}
}
do
{
random = g_rand_int (rand) >> right_shift;
} while (random >= dist);
}
return min + random;
}
/* transform [0..2^32-1] -> [0..1) */
#define G_RAND_DOUBLE_TRANSFORM 2.3283064365386963e-10
gdouble
g_rand_double (GRand* rand)
{
return g_rand_int (rand) * G_RAND_DOUBLE_TRANSFORM;
}
gdouble
g_rand_double_range (GRand* rand, gdouble min, gdouble max)
{
return g_rand_int (rand) * ((max - min) * G_RAND_DOUBLE_TRANSFORM) + min;
}
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;
}
gint32
g_random_int_range (gint32 min, gint32 max)
{
gint32 result;
G_LOCK (global_random);
if (!global_random)
global_random = g_rand_new ();
result = g_rand_int_range (global_random, min, max);
G_UNLOCK (global_random);
return result;
}
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;
}
gdouble
g_random_double_range (gdouble min, gdouble max)
{
double result;
G_LOCK (global_random);
if (!global_random)
global_random = g_rand_new ();
result = g_rand_double_range (global_random, min, max);
G_UNLOCK (global_random);
return result;
}
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);
}