1 /* GLIB - Library of useful routines for C programming
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
4 * SPDX-License-Identifier: LGPL-2.1-or-later
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
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/.
39 #include <sys/types.h>
45 #if defined(PLATFORM_WINDOWS)
46 #include <process.h> // for getpid()
47 #if (defined(_MSC_VER) && _MSC_VER >= 1400) || defined(__MINGW64_VERSION_MAJOR)
48 extern errno_t rand_s (unsigned int *randomValue);
56 * The GdRand struct is an opaque data structure. It should only be
57 * accessed through the gd_rand_* functions.
63 #define MATRIX_A 0x9908b0df // constant vector a
64 #define UPPER_MASK 0x80000000 // most significant w-r bits
65 #define LOWER_MASK 0x7fffffff // least significant r bits
67 // Tempering parameters
68 #define TEMPERING_MASK_B 0x9d2c5680
69 #define TEMPERING_MASK_C 0xefc60000
70 #define TEMPERING_SHIFT_U(y) (y >> 11)
71 #define TEMPERING_SHIFT_S(y) (y << 7)
72 #define TEMPERING_SHIFT_T(y) (y << 15)
73 #define TEMPERING_SHIFT_L(y) (y >> 18)
77 unsigned int mt[N]; // the array for the state vector
82 * gd_rand_new_with_seed: (constructor)
83 * @seed: a value to initialize the random number generator
85 * Creates a new random number generator initialized with @seed.
87 * Returns: (transfer full): the new #GdRand
90 gd_rand_new_with_seed (unsigned int seed)
92 GdRand *rand = checked_calloc(sizeof(GdRand));
93 gd_rand_set_seed (rand, seed);
98 * gd_rand_new_with_seed_array: (constructor)
99 * @seed: an array of seeds to initialize the random number generator
100 * @seed_length: an array of seeds to initialize the random number
103 * Creates a new random number generator initialized with @seed.
105 * Returns: (transfer full): the new #GdRand
110 gd_rand_new_with_seed_array (const unsigned int *seed, unsigned int seed_length)
112 GdRand *rand = checked_calloc(sizeof(GdRand));
113 gd_rand_set_seed_array (rand, seed, seed_length);
119 * gd_rand_new: (constructor)
121 * Creates a new random number generator initialized with a seed taken
122 * either from `/dev/urandom` (if existing) or from the current time
125 * On Windows, the seed is taken from rand_s().
127 * Returns: (transfer full): the new #GdRand
132 unsigned int seed[4];
134 #if defined(PLATFORM_UNIX)
135 static boolean dev_urandom_exists = TRUE;
137 if (dev_urandom_exists)
143 dev_urandom = fopen ("/dev/urandom", "rbe");
145 while (dev_urandom == NULL && errno == EINTR);
151 setvbuf (dev_urandom, NULL, _IONBF, 0);
156 r = fread (seed, sizeof (seed), 1, dev_urandom);
158 while (errno == EINTR);
161 dev_urandom_exists = FALSE;
163 fclose (dev_urandom);
167 dev_urandom_exists = FALSE;
171 if (!dev_urandom_exists)
175 clock_gettime(CLOCK_REALTIME, &now);
177 seed[0] = now.tv_sec;
178 seed[1] = now.tv_nsec;
180 seed[3] = getppid ();
182 #else // PLATFORM_WINDOWS
183 /* rand_s() is only available since Visual Studio 2005 and
184 * MinGW-w64 has a wrapper that will emulate rand_s() if it's not in msvcrt
186 #if (defined(_MSC_VER) && _MSC_VER >= 1400) || defined(__MINGW64_VERSION_MAJOR)
189 for (i = 0; i < ARRAY_SIZE(seed); i++)
192 #warning Using insecure seed for random number generation because of missing rand_s() in Windows XP
195 gd_get_current_time (&now);
197 seed[0] = now.tv_sec;
198 seed[1] = now.tv_usec;
205 return gd_rand_new_with_seed_array (seed, 4);
212 * Frees the memory allocated for the #GdRand.
215 gd_rand_free (GdRand *rand)
225 * Copies a #GdRand into a new one with the same exact state as before.
226 * This way you can take a snapshot of the random number generator for
229 * Returns: (transfer full): the new #GdRand
234 gd_rand_copy (GdRand *rand)
241 new_rand = checked_calloc(sizeof(GdRand));
242 memcpy(new_rand, rand, sizeof(GdRand));
250 * @seed: a value to reinitialize the random number generator
252 * Sets the seed for the random number generator #GdRand to @seed.
255 gd_rand_set_seed (GdRand *rand, unsigned int seed)
260 // See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier.
261 // In the previous version (see above), MSBs of the
262 // seed affect only MSBs of the array mt[].
265 for (rand->mti = 1; rand->mti < N; rand->mti++)
266 rand->mt[rand->mti] = 1812433253UL *
267 (rand->mt[rand->mti - 1] ^ (rand->mt[rand->mti - 1] >> 30)) + rand->mti;
271 * gd_rand_set_seed_array:
273 * @seed: array to initialize with
274 * @seed_length: length of array
276 * Initializes the random number generator by an array of longs.
277 * Array can be of arbitrary size, though only the first 624 values
278 * are taken. This function is useful if you have many low entropy
279 * seeds, or if you require more then 32 bits of actual entropy for
285 gd_rand_set_seed_array (GdRand *rand, const unsigned int *seed, unsigned int seed_length)
287 unsigned int i, j, k;
289 if (rand == NULL || seed_length < 1)
292 gd_rand_set_seed (rand, 19650218UL);
296 k = (N > seed_length ? N : seed_length);
300 rand->mt[i] = ((rand->mt[i] ^ ((rand->mt[i - 1] ^ (rand->mt[i - 1] >> 30)) * 1664525UL))
301 + seed[j] + j); // non linear
302 rand->mt[i] &= 0xffffffffUL; // for WORDSIZE > 32 machines
308 rand->mt[0] = rand->mt[N - 1];
312 if (j >= seed_length)
316 for (k = N - 1; k; k--)
318 rand->mt[i] = ((rand->mt[i] ^ ((rand->mt[i - 1] ^ (rand->mt[i - 1] >> 30)) * 1566083941UL))
320 rand->mt[i] &= 0xffffffffUL; // for WORDSIZE > 32 machines
325 rand->mt[0] = rand->mt[N - 1];
330 rand->mt[0] = 0x80000000UL; // MSB is 1; assuring non-zero initial array
337 * Returns a random #boolean from @rand_.
338 * This corresponds to an unbiased coin toss.
340 * Returns: a random #boolean
346 * Returns the next random unsigned int from @rand_ equally distributed over
347 * the range [0..2^32-1].
349 * Returns: a random number
352 gd_rand_int (GdRand *rand)
355 static const unsigned int mag01[2] = { 0x0, MATRIX_A };
356 // mag01[x] = x * MATRIX_A for x=0,1
363 // generate N words at one time
366 for (kk = 0; kk < N - M; kk++)
368 y = (rand->mt[kk] & UPPER_MASK) | (rand->mt[kk + 1] & LOWER_MASK);
369 rand->mt[kk] = rand->mt[kk + M] ^ (y >> 1) ^ mag01[y & 0x1];
372 for (; kk < N - 1; kk++)
374 y = (rand->mt[kk] & UPPER_MASK) | (rand->mt[kk + 1] & LOWER_MASK);
375 rand->mt[kk] = rand->mt[kk + (M - N)] ^ (y >> 1) ^ mag01[y & 0x1];
378 y = (rand->mt[N - 1] & UPPER_MASK) | (rand->mt[0] & LOWER_MASK);
379 rand->mt[N - 1] = rand->mt[M - 1] ^ (y >> 1) ^ mag01[y & 0x1];
384 y = rand->mt[rand->mti++];
385 y ^= TEMPERING_SHIFT_U(y);
386 y ^= TEMPERING_SHIFT_S(y) & TEMPERING_MASK_B;
387 y ^= TEMPERING_SHIFT_T(y) & TEMPERING_MASK_C;
388 y ^= TEMPERING_SHIFT_L(y);
393 // transform [0..2^32] -> [0..1]
394 #define GD_RAND_DOUBLE_TRANSFORM 2.3283064365386962890625e-10
399 * @begin: lower closed bound of the interval
400 * @end: upper open bound of the interval
402 * Returns the next random #int from @rand_ equally distributed over
403 * the range [@begin..@end-1].
405 * Returns: a random number
408 gd_rand_int_range (GdRand *rand, int begin, int end)
410 unsigned int dist = end - begin;
411 unsigned int random = 0;
413 if (rand == NULL || end <= begin)
419 /* maxvalue is set to the predecessor of the greatest
420 * multiple of dist less or equal 2^32.
422 unsigned int maxvalue;
423 if (dist <= 0x80000000u) // 2^31
425 // maxvalue = 2^32 - 1 - (2^32 % dist)
426 unsigned int leftover = (0x80000000u % dist) * 2;
427 if (leftover >= dist) leftover -= dist;
428 maxvalue = 0xffffffffu - leftover;
436 random = gd_rand_int (rand);
437 while (random > maxvalue);
441 return begin + random;
448 * Returns the next random #double from @rand_ equally distributed over
451 * Returns: a random number
454 gd_rand_double (GdRand *rand)
456 /* We set all 52 bits after the point for this, not only the first
457 32. That's why we need two calls to gd_rand_int */
458 double retval = gd_rand_int(rand) * GD_RAND_DOUBLE_TRANSFORM;
459 retval = (retval + gd_rand_int(rand)) * GD_RAND_DOUBLE_TRANSFORM;
461 /* The following might happen due to very bad rounding luck, but
462 * actually this should be more than rare, we just try again then */
464 return gd_rand_double (rand);
470 * gd_rand_double_range:
472 * @begin: lower closed bound of the interval
473 * @end: upper open bound of the interval
475 * Returns the next random #double from @rand_ equally distributed over
476 * the range [@begin..@end).
478 * Returns: a random number
481 gd_rand_double_range (GdRand *rand, double begin, double end)
485 r = gd_rand_double(rand);
487 return r * end - (r - 1) * begin;
491 get_global_random (void)
493 static GdRand *global_random;
495 // called while locked
497 global_random = gd_rand_new();
499 return global_random;
505 * Returns a random #gboolean.
506 * This corresponds to an unbiased coin toss.
508 * Returns: a random #gboolean
513 * Return a random #guint32 equally distributed over the range
516 * Returns: a random number
523 result = gd_rand_int(get_global_random());
529 * gd_random_int_range:
530 * @begin: lower closed bound of the interval
531 * @end: upper open bound of the interval
533 * Returns a random #int equally distributed over the range
536 * Returns: a random number
539 gd_random_int_range (int begin, int end)
543 result = gd_rand_int_range (get_global_random(), begin, end);
551 * Returns a random #double equally distributed over the range [0..1).
553 * Returns: a random number
556 gd_random_double (void)
560 result = gd_rand_double(get_global_random());
566 * gd_random_double_range:
567 * @begin: lower closed bound of the interval
568 * @end: upper open bound of the interval
570 * Returns a random #double equally distributed over the range
573 * Returns: a random number
576 gd_random_double_range (double begin, double end)
580 result = gd_rand_double_range(get_global_random(), begin, end);