/* 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 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. */ /* 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 1997-1999. 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; }; 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 = 0; GTimeVal now; static gboolean dev_random_exists = TRUE; if (dev_random_exists) { FILE* dev_random = fopen("/dev/random", "rb"); if (dev_random) { if (fread (&seed, sizeof (seed), 1, dev_random) != 1) seed = 0; else dev_random_exists = FALSE; fclose (dev_random); } else dev_random_exists = FALSE; } /* Using /dev/random alone makes the seed computable for the outside. This might pose security problems somewhere. This should yield better values */ 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] */ rand->mt[0]= seed & 0xffffffff; for (rand->mti=1; rand->mtimti++) 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;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; } 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); }