/* 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 , 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 . */ /* * 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 #include #include 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; #ifdef G_OS_UNIX 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; } #else static gboolean dev_urandom_exists = FALSE; #endif 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->mtimti++) 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;kkmt[kk]&UPPER_MASK)|(rand->mt[kk+1]&LOWER_MASK); rand->mt[kk] = rand->mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1]; } for (;kkmt[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); }