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>
42 #if defined(PLATFORM_WINDOWS)
43 #include <process.h> /* for getpid() */
52 * The GdRand struct is an opaque data structure. It should only be
53 * accessed through the gd_rand_* functions.
56 /* Period parameters */
59 #define MATRIX_A 0x9908b0df /* constant vector a */
60 #define UPPER_MASK 0x80000000 /* most significant w-r bits */
61 #define LOWER_MASK 0x7fffffff /* least significant r bits */
63 /* Tempering parameters */
64 #define TEMPERING_MASK_B 0x9d2c5680
65 #define TEMPERING_MASK_C 0xefc60000
66 #define TEMPERING_SHIFT_U(y) (y >> 11)
67 #define TEMPERING_SHIFT_S(y) (y << 7)
68 #define TEMPERING_SHIFT_T(y) (y << 15)
69 #define TEMPERING_SHIFT_L(y) (y >> 18)
73 unsigned int mt[N]; /* the array for the state vector */
78 * gd_rand_new_with_seed: (constructor)
79 * @seed: a value to initialize the random number generator
81 * Creates a new random number generator initialized with @seed.
83 * Returns: (transfer full): the new #GdRand
86 gd_rand_new_with_seed (unsigned int seed)
88 GdRand *rand = checked_calloc(sizeof(GdRand));
89 gd_rand_set_seed (rand, seed);
94 * gd_rand_new_with_seed_array: (constructor)
95 * @seed: an array of seeds to initialize the random number generator
96 * @seed_length: an array of seeds to initialize the random number
99 * Creates a new random number generator initialized with @seed.
101 * Returns: (transfer full): the new #GdRand
106 gd_rand_new_with_seed_array (const unsigned int *seed, unsigned int seed_length)
108 GdRand *rand = checked_calloc(sizeof(GdRand));
109 gd_rand_set_seed_array (rand, seed, seed_length);
115 * gd_rand_new: (constructor)
117 * Creates a new random number generator initialized with a seed taken
118 * either from `/dev/urandom` (if existing) or from the current time
121 * On Windows, the seed is taken from rand_s().
123 * Returns: (transfer full): the new #GdRand
128 unsigned int seed[4];
130 #if defined(PLATFORM_UNIX)
131 static boolean dev_urandom_exists = TRUE;
133 if (dev_urandom_exists)
139 dev_urandom = fopen ("/dev/urandom", "rbe");
141 while (dev_urandom == NULL && errno == EINTR);
147 setvbuf (dev_urandom, NULL, _IONBF, 0);
152 r = fread (seed, sizeof (seed), 1, dev_urandom);
154 while (errno == EINTR);
157 dev_urandom_exists = FALSE;
159 fclose (dev_urandom);
163 dev_urandom_exists = FALSE;
167 if (!dev_urandom_exists)
171 clock_gettime(CLOCK_REALTIME, &now);
173 seed[0] = now.tv_sec;
174 seed[1] = now.tv_nsec;
176 seed[3] = getppid ();
178 #else /* PLATFORM_WINDOWS */
179 /* rand_s() is only available since Visual Studio 2005 and
180 * MinGW-w64 has a wrapper that will emulate rand_s() if it's not in msvcrt
182 #if (defined(_MSC_VER) && _MSC_VER >= 1400) || defined(__MINGW64_VERSION_MAJOR)
185 for (i = 0; i < ARRAY_SIZE(seed); i++)
188 #warning Using insecure seed for random number generation because of missing rand_s() in Windows XP
191 gd_get_current_time (&now);
193 seed[0] = now.tv_sec;
194 seed[1] = now.tv_usec;
201 return gd_rand_new_with_seed_array (seed, 4);
208 * Frees the memory allocated for the #GdRand.
211 gd_rand_free (GdRand *rand)
221 * Copies a #GdRand into a new one with the same exact state as before.
222 * This way you can take a snapshot of the random number generator for
225 * Returns: (transfer full): the new #GdRand
230 gd_rand_copy (GdRand *rand)
237 new_rand = checked_calloc(sizeof(GdRand));
238 memcpy(new_rand, rand, sizeof(GdRand));
246 * @seed: a value to reinitialize the random number generator
248 * Sets the seed for the random number generator #GdRand to @seed.
251 gd_rand_set_seed (GdRand *rand, unsigned int seed)
256 /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
257 /* In the previous version (see above), MSBs of the */
258 /* seed affect only MSBs of the array mt[]. */
261 for (rand->mti = 1; rand->mti < N; rand->mti++)
262 rand->mt[rand->mti] = 1812433253UL *
263 (rand->mt[rand->mti - 1] ^ (rand->mt[rand->mti - 1] >> 30)) + rand->mti;
267 * gd_rand_set_seed_array:
269 * @seed: array to initialize with
270 * @seed_length: length of array
272 * Initializes the random number generator by an array of longs.
273 * Array can be of arbitrary size, though only the first 624 values
274 * are taken. This function is useful if you have many low entropy
275 * seeds, or if you require more then 32 bits of actual entropy for
281 gd_rand_set_seed_array (GdRand *rand, const unsigned int *seed, unsigned int seed_length)
283 unsigned int i, j, k;
285 if (rand == NULL || seed_length < 1)
288 gd_rand_set_seed (rand, 19650218UL);
292 k = (N > seed_length ? N : seed_length);
296 rand->mt[i] = ((rand->mt[i] ^ ((rand->mt[i - 1] ^ (rand->mt[i - 1] >> 30)) * 1664525UL))
297 + seed[j] + j); /* non linear */
298 rand->mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
304 rand->mt[0] = rand->mt[N - 1];
308 if (j >= seed_length)
312 for (k = N - 1; k; k--)
314 rand->mt[i] = ((rand->mt[i] ^ ((rand->mt[i - 1] ^ (rand->mt[i - 1] >> 30)) * 1566083941UL))
315 - i); /* non linear */
316 rand->mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
321 rand->mt[0] = rand->mt[N - 1];
326 rand->mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */
333 * Returns a random #boolean from @rand_.
334 * This corresponds to an unbiased coin toss.
336 * Returns: a random #boolean
342 * Returns the next random unsigned int from @rand_ equally distributed over
343 * the range [0..2^32-1].
345 * Returns: a random number
348 gd_rand_int (GdRand *rand)
351 static const unsigned int mag01[2] = { 0x0, MATRIX_A };
352 /* mag01[x] = x * MATRIX_A for x=0,1 */
359 /* generate N words at one time */
362 for (kk = 0; kk < N - M; kk++)
364 y = (rand->mt[kk] & UPPER_MASK) | (rand->mt[kk + 1] & LOWER_MASK);
365 rand->mt[kk] = rand->mt[kk + M] ^ (y >> 1) ^ mag01[y & 0x1];
368 for (; kk < N - 1; kk++)
370 y = (rand->mt[kk] & UPPER_MASK) | (rand->mt[kk + 1] & LOWER_MASK);
371 rand->mt[kk] = rand->mt[kk + (M - N)] ^ (y >> 1) ^ mag01[y & 0x1];
374 y = (rand->mt[N - 1] & UPPER_MASK) | (rand->mt[0] & LOWER_MASK);
375 rand->mt[N - 1] = rand->mt[M - 1] ^ (y >> 1) ^ mag01[y & 0x1];
380 y = rand->mt[rand->mti++];
381 y ^= TEMPERING_SHIFT_U(y);
382 y ^= TEMPERING_SHIFT_S(y) & TEMPERING_MASK_B;
383 y ^= TEMPERING_SHIFT_T(y) & TEMPERING_MASK_C;
384 y ^= TEMPERING_SHIFT_L(y);
392 * @begin: lower closed bound of the interval
393 * @end: upper open bound of the interval
395 * Returns the next random #int from @rand_ equally distributed over
396 * the range [@begin..@end-1].
398 * Returns: a random number
401 gd_rand_int_range (GdRand *rand, int begin, int end)
403 unsigned int dist = end - begin;
404 unsigned int random = 0;
406 if (rand == NULL || end <= begin)
412 /* maxvalue is set to the predecessor of the greatest
413 * multiple of dist less or equal 2^32.
415 unsigned int maxvalue;
416 if (dist <= 0x80000000u) /* 2^31 */
418 /* maxvalue = 2^32 - 1 - (2^32 % dist) */
419 unsigned int leftover = (0x80000000u % dist) * 2;
420 if (leftover >= dist) leftover -= dist;
421 maxvalue = 0xffffffffu - leftover;
429 random = gd_rand_int (rand);
430 while (random > maxvalue);
434 return begin + random;
438 get_global_random (void)
440 static GdRand *global_random;
442 /* called while locked */
444 global_random = gd_rand_new();
446 return global_random;
450 * gd_random_int_range:
451 * @begin: lower closed bound of the interval
452 * @end: upper open bound of the interval
454 * Returns a random #int equally distributed over the range
457 * Returns: a random number
460 gd_random_int_range (int begin, int end)
464 result = gd_rand_int_range (get_global_random(), begin, end);