1 /* GLIB - Library of useful routines for C programming
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
20 /* Originally developed and coded by Makoto Matsumoto and Takuji
21 * Nishimura. Please mail <matumoto@math.keio.ac.jp>, if you're using
22 * code from this file in your own programs or libraries.
23 * Further information on the Mersenne Twister can be found at
24 * http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
25 * This code was adapted to glib by Sebastian Wilhelmi.
29 * Modified by the GLib Team and others 1997-2000. See the AUTHORS
30 * file for a list of people on the GLib Team. See the ChangeLog
31 * files for a list of changes. These files are distributed with
32 * GLib at ftp://ftp.gtk.org/pub/gtk/.
45 #include <sys/types.h>
51 #include "gthreadinit.h"
55 #include <process.h> /* For getpid() */
58 G_LOCK_DEFINE_STATIC (global_random);
59 static GRand* global_random = NULL;
61 /* Period parameters */
64 #define MATRIX_A 0x9908b0df /* constant vector a */
65 #define UPPER_MASK 0x80000000 /* most significant w-r bits */
66 #define LOWER_MASK 0x7fffffff /* least significant r bits */
68 /* Tempering parameters */
69 #define TEMPERING_MASK_B 0x9d2c5680
70 #define TEMPERING_MASK_C 0xefc60000
71 #define TEMPERING_SHIFT_U(y) (y >> 11)
72 #define TEMPERING_SHIFT_S(y) (y << 7)
73 #define TEMPERING_SHIFT_T(y) (y << 15)
74 #define TEMPERING_SHIFT_L(y) (y >> 18)
77 get_random_version (void)
79 static gboolean initialized = FALSE;
80 static guint random_version;
84 const gchar *version_string = g_getenv ("G_RANDOM_VERSION");
85 if (!version_string || version_string[0] == '\000' ||
86 strcmp (version_string, "2.2") == 0)
88 else if (strcmp (version_string, "2.0") == 0)
92 g_warning ("Unknown G_RANDOM_VERSION \"%s\". Using version 2.2.",
99 return random_version;
102 /* This is called from g_thread_init(). It's used to
103 * initialize some static data in a threadsafe way.
106 _g_rand_thread_init (void)
108 (void)get_random_version ();
113 guint32 mt[N]; /* the array for the state vector */
118 * g_rand_new_with_seed:
119 * @seed: a value to initialize the random number generator.
121 * Creates a new random number generator initialized with @seed.
123 * Return value: the new #GRand.
126 g_rand_new_with_seed (guint32 seed)
128 GRand *rand = g_new0 (GRand, 1);
129 g_rand_set_seed (rand, seed);
134 * g_rand_new_with_seed_array:
135 * @seed: an array of seeds to initialize the random number generator.
136 * @seed_length: an array of seeds to initialize the random number generator.
138 * Creates a new random number generator initialized with @seed.
140 * Return value: the new #GRand.
145 g_rand_new_with_seed_array (const guint32 *seed, guint seed_length)
147 GRand *rand = g_new0 (GRand, 1);
148 g_rand_set_seed_array (rand, seed, seed_length);
155 * Creates a new random number generator initialized with a seed taken
156 * either from <filename>/dev/urandom</filename> (if existing) or from
157 * the current time (as a fallback).
159 * Return value: the new #GRand.
167 static gboolean dev_urandom_exists = TRUE;
169 if (dev_urandom_exists)
176 dev_urandom = fopen("/dev/urandom", "rb");
178 while G_UNLIKELY (errno == EINTR);
187 r = fread (seed, sizeof (seed), 1, dev_urandom);
189 while G_UNLIKELY (errno == EINTR);
192 dev_urandom_exists = FALSE;
197 fclose (dev_urandom);
199 while G_UNLIKELY (errno == EINTR);
202 dev_urandom_exists = FALSE;
205 static gboolean dev_urandom_exists = FALSE;
208 if (!dev_urandom_exists)
210 g_get_current_time (&now);
211 seed[0] = now.tv_sec;
212 seed[1] = now.tv_usec;
215 seed[3] = getppid ();
221 return g_rand_new_with_seed_array (seed, 4);
228 * Frees the memory allocated for the #GRand.
231 g_rand_free (GRand* rand)
233 g_return_if_fail (rand != NULL);
242 * Copies a #GRand into a new one with the same exact state as before.
243 * This way you can take a snapshot of the random number generator for
246 * Return value: the new #GRand.
251 g_rand_copy (GRand* rand)
255 g_return_val_if_fail (rand != NULL, NULL);
257 new_rand = g_new0 (GRand, 1);
258 memcpy (new_rand, rand, sizeof (GRand));
266 * @seed: a value to reinitialize the random number generator.
268 * Sets the seed for the random number generator #GRand to @seed.
271 g_rand_set_seed (GRand* rand, guint32 seed)
273 g_return_if_fail (rand != NULL);
275 switch (get_random_version ())
278 /* setting initial seeds to mt[N] using */
279 /* the generator Line 25 of Table 1 in */
280 /* [KNUTH 1981, The Art of Computer Programming */
281 /* Vol. 2 (2nd Ed.), pp102] */
283 if (seed == 0) /* This would make the PRNG procude only zeros */
284 seed = 0x6b842128; /* Just set it to another number */
287 for (rand->mti=1; rand->mti<N; rand->mti++)
288 rand->mt[rand->mti] = (69069 * rand->mt[rand->mti-1]);
292 /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
293 /* In the previous version (see above), MSBs of the */
294 /* seed affect only MSBs of the array mt[]. */
297 for (rand->mti=1; rand->mti<N; rand->mti++)
298 rand->mt[rand->mti] = 1812433253UL *
299 (rand->mt[rand->mti-1] ^ (rand->mt[rand->mti-1] >> 30)) + rand->mti;
302 g_assert_not_reached ();
307 * g_rand_set_seed_array:
309 * @seed: array to initialize with
310 * @seed_length: length of array
312 * Initializes the random number generator by an array of
313 * longs. Array can be of arbitrary size, though only the
314 * first 624 values are taken. This function is useful
315 * if you have many low entropy seeds, or if you require more then
316 * 32bits of actual entropy for your application.
321 g_rand_set_seed_array (GRand* rand, const guint32 *seed, guint seed_length)
325 g_return_if_fail (rand != NULL);
326 g_return_if_fail (seed_length >= 1);
328 g_rand_set_seed (rand, 19650218UL);
331 k = (N>seed_length ? N : seed_length);
334 rand->mt[i] = (rand->mt[i] ^
335 ((rand->mt[i-1] ^ (rand->mt[i-1] >> 30)) * 1664525UL))
336 + seed[j] + j; /* non linear */
337 rand->mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
341 rand->mt[0] = rand->mt[N-1];
349 rand->mt[i] = (rand->mt[i] ^
350 ((rand->mt[i-1] ^ (rand->mt[i-1] >> 30)) * 1566083941UL))
351 - i; /* non linear */
352 rand->mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
356 rand->mt[0] = rand->mt[N-1];
361 rand->mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */
368 * Returns the next random #guint32 from @rand_ equally distributed over
369 * the range [0..2^32-1].
371 * Return value: A random number.
374 g_rand_int (GRand* rand)
377 static const guint32 mag01[2]={0x0, MATRIX_A};
378 /* mag01[x] = x * MATRIX_A for x=0,1 */
380 g_return_val_if_fail (rand != NULL, 0);
382 if (rand->mti >= N) { /* generate N words at one time */
385 for (kk=0;kk<N-M;kk++) {
386 y = (rand->mt[kk]&UPPER_MASK)|(rand->mt[kk+1]&LOWER_MASK);
387 rand->mt[kk] = rand->mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1];
390 y = (rand->mt[kk]&UPPER_MASK)|(rand->mt[kk+1]&LOWER_MASK);
391 rand->mt[kk] = rand->mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1];
393 y = (rand->mt[N-1]&UPPER_MASK)|(rand->mt[0]&LOWER_MASK);
394 rand->mt[N-1] = rand->mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1];
399 y = rand->mt[rand->mti++];
400 y ^= TEMPERING_SHIFT_U(y);
401 y ^= TEMPERING_SHIFT_S(y) & TEMPERING_MASK_B;
402 y ^= TEMPERING_SHIFT_T(y) & TEMPERING_MASK_C;
403 y ^= TEMPERING_SHIFT_L(y);
408 /* transform [0..2^32] -> [0..1] */
409 #define G_RAND_DOUBLE_TRANSFORM 2.3283064365386962890625e-10
414 * @begin: lower closed bound of the interval.
415 * @end: upper open bound of the interval.
417 * Returns the next random #gint32 from @rand_ equally distributed over
418 * the range [@begin..@end-1].
420 * Return value: A random number.
423 g_rand_int_range (GRand* rand, gint32 begin, gint32 end)
425 guint32 dist = end - begin;
428 g_return_val_if_fail (rand != NULL, begin);
429 g_return_val_if_fail (end > begin, begin);
431 switch (get_random_version ())
434 if (dist <= 0x10000L) /* 2^16 */
436 /* This method, which only calls g_rand_int once is only good
437 * for (end - begin) <= 2^16, because we only have 32 bits set
438 * from the one call to g_rand_int (). */
440 /* we are using (trans + trans * trans), because g_rand_int only
441 * covers [0..2^32-1] and thus g_rand_int * trans only covers
442 * [0..1-2^-32], but the biggest double < 1 is 1-2^-52.
445 gdouble double_rand = g_rand_int (rand) *
446 (G_RAND_DOUBLE_TRANSFORM +
447 G_RAND_DOUBLE_TRANSFORM * G_RAND_DOUBLE_TRANSFORM);
449 random = (gint32) (double_rand * dist);
453 /* Now we use g_rand_double_range (), which will set 52 bits for
454 us, so that it is safe to round and still get a decent
456 random = (gint32) g_rand_double_range (rand, 0, dist);
464 /* maxvalue is set to the predecessor of the greatest
465 * multiple of dist less or equal 2^32. */
467 if (dist <= 0x80000000u) /* 2^31 */
469 /* maxvalue = 2^32 - 1 - (2^32 % dist) */
470 guint32 leftover = (0x80000000u % dist) * 2;
471 if (leftover >= dist) leftover -= dist;
472 maxvalue = 0xffffffffu - leftover;
478 random = g_rand_int (rand);
479 while (random > maxvalue);
485 random = 0; /* Quiet GCC */
486 g_assert_not_reached ();
489 return begin + random;
496 * Returns the next random #gdouble from @rand_ equally distributed over
499 * Return value: A random number.
502 g_rand_double (GRand* rand)
504 /* We set all 52 bits after the point for this, not only the first
505 32. Thats why we need two calls to g_rand_int */
506 gdouble retval = g_rand_int (rand) * G_RAND_DOUBLE_TRANSFORM;
507 retval = (retval + g_rand_int (rand)) * G_RAND_DOUBLE_TRANSFORM;
509 /* The following might happen due to very bad rounding luck, but
510 * actually this should be more than rare, we just try again then */
512 return g_rand_double (rand);
518 * g_rand_double_range:
520 * @begin: lower closed bound of the interval.
521 * @end: upper open bound of the interval.
523 * Returns the next random #gdouble from @rand_ equally distributed over
524 * the range [@begin..@end).
526 * Return value: A random number.
529 g_rand_double_range (GRand* rand, gdouble begin, gdouble end)
531 return g_rand_double (rand) * (end - begin) + begin;
537 * Return a random #guint32 equally distributed over the range
540 * Return value: A random number.
546 G_LOCK (global_random);
548 global_random = g_rand_new ();
550 result = g_rand_int (global_random);
551 G_UNLOCK (global_random);
556 * g_random_int_range:
557 * @begin: lower closed bound of the interval.
558 * @end: upper open bound of the interval.
560 * Returns a random #gint32 equally distributed over the range
563 * Return value: A random number.
566 g_random_int_range (gint32 begin, gint32 end)
569 G_LOCK (global_random);
571 global_random = g_rand_new ();
573 result = g_rand_int_range (global_random, begin, end);
574 G_UNLOCK (global_random);
581 * Returns a random #gdouble equally distributed over the range [0..1).
583 * Return value: A random number.
586 g_random_double (void)
589 G_LOCK (global_random);
591 global_random = g_rand_new ();
593 result = g_rand_double (global_random);
594 G_UNLOCK (global_random);
599 * g_random_double_range:
600 * @begin: lower closed bound of the interval.
601 * @end: upper open bound of the interval.
603 * Returns a random #gdouble equally distributed over the range [@begin..@end).
605 * Return value: A random number.
608 g_random_double_range (gdouble begin, gdouble end)
611 G_LOCK (global_random);
613 global_random = g_rand_new ();
615 result = g_rand_double_range (global_random, begin, end);
616 G_UNLOCK (global_random);
622 * @seed: a value to reinitialize the global random number generator.
624 * Sets the seed for the global random number generator, which is used
625 * by the <function>g_random_*</function> functions, to @seed.
628 g_random_set_seed (guint32 seed)
630 G_LOCK (global_random);
632 global_random = g_rand_new_with_seed (seed);
634 g_rand_set_seed (global_random, seed);
635 G_UNLOCK (global_random);
640 #include "galiasdef.c"