* 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 <wilhelmi@ira.uka.de>.
+ * This code was adapted to glib by Sebastian Wilhelmi.
*/
/*
* MT safe
*/
-#include <glib.h>
+#include "config.h"
+
#include <math.h>
#include <stdio.h>
+#include <string.h>
+
+#include "glib.h"
+#include "gthreadinit.h"
G_LOCK_DEFINE_STATIC (global_random);
static GRand* global_random = NULL;
#define TEMPERING_SHIFT_T(y) (y << 15)
#define TEMPERING_SHIFT_L(y) (y >> 18)
+static guint
+get_random_version (void)
+{
+ static gboolean initialized = FALSE;
+ static guint random_version;
+
+ if (!initialized)
+ {
+ const gchar *version_string = g_getenv ("G_RANDOM_VERSION");
+ if (!version_string || version_string[0] == '\000' ||
+ strcmp (version_string, "2.2") == 0)
+ random_version = 22;
+ else if (strcmp (version_string, "2.0") == 0)
+ random_version = 20;
+ else
+ {
+ g_warning ("Unknown G_RANDOM_VERSION \"%s\". Using version 2.2.",
+ version_string);
+ random_version = 22;
+ }
+ initialized = TRUE;
+ }
+
+ return random_version;
+}
+
+/* This is called from g_thread_init(). It's used to
+ * initialize some static data in a threadsafe way.
+ */
+void
+_g_rand_thread_init (void)
+{
+ (void)get_random_version ();
+}
+
struct _GRand
{
guint32 mt[N]; /* the array for the state vector */
* 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).
+ * either from <filename>/dev/urandom</filename> (if existing) or from
+ * the current time (as a fallback).
*
* Return value: the new #GRand.
**/
{
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");
else
dev_urandom_exists = FALSE;
}
+#else
+ static gboolean dev_urandom_exists = FALSE;
+#endif
+
if (!dev_urandom_exists)
{
g_get_current_time (&now);
/**
* g_rand_free:
- * @rand: a #GRand.
+ * @rand_: a #GRand.
*
* Frees the memory allocated for the #GRand.
**/
/**
* g_rand_set_seed:
- * @rand: a #GRand.
+ * @rand_: a #GRand.
* @seed: a value to reinitialize the random number generator.
*
* Sets the seed for the random number generator #GRand to @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->mti<N; rand->mti++)
- rand->mt[rand->mti] = (69069 * rand->mt[rand->mti-1]) & 0xffffffff;
+ switch (get_random_version ())
+ {
+ case 20:
+ /* 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;
+ for (rand->mti=1; rand->mti<N; rand->mti++)
+ rand->mt[rand->mti] = (69069 * rand->mt[rand->mti-1]);
+
+ break;
+ case 22:
+ /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
+ /* In the previous version (see above), MSBs of the */
+ /* seed affect only MSBs of the array mt[]. */
+
+ rand->mt[0]= seed;
+ for (rand->mti=1; rand->mti<N; rand->mti++)
+ rand->mt[rand->mti] = 1812433253UL *
+ (rand->mt[rand->mti-1] ^ (rand->mt[rand->mti-1] >> 30)) + rand->mti;
+ break;
+ default:
+ g_assert_not_reached ();
+ }
}
/**
* g_rand_int:
- * @rand: a #GRand.
+ * @rand_: a #GRand.
*
- * Return the next random #guint32 from @rand equaly distributed over
+ * Returns the next random #guint32 from @rand_ equally distributed over
* the range [0..2^32-1].
*
* Return value: A random number.
return y;
}
+/* transform [0..2^32] -> [0..1] */
+#define G_RAND_DOUBLE_TRANSFORM 2.3283064365386962890625e-10
+
/**
* g_rand_int_range:
- * @rand: a #GRand.
- * @min: lower closed bound of the interval.
- * @max: upper open bound of the interval.
+ * @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 [@min..@max-1].
+ * Returns the next random #gint32 from @rand_ equally distributed over
+ * the range [@begin..@end-1].
*
* Return value: A random number.
**/
gint32
-g_rand_int_range (GRand* rand, gint32 min, gint32 max)
+g_rand_int_range (GRand* rand, gint32 begin, gint32 end)
{
- guint32 dist = max - min;
+ guint32 dist = end - begin;
guint32 random;
- g_return_val_if_fail (rand != NULL, min);
- g_return_val_if_fail (max > min, min);
+ g_return_val_if_fail (rand != NULL, begin);
+ g_return_val_if_fail (end > begin, begin);
- if (dist <= 0x10000L) /* 2^16 */
+ switch (get_random_version ())
{
- /* 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 */
+ case 20:
+ if (dist <= 0x10000L) /* 2^16 */
{
- right_shift = 0;
+ /* 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
{
- while (dist >= border)
+ /* 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);
+ }
+ break;
+ case 22:
+ if (dist == 0)
+ random = 0;
+ else
+ {
+ /* maxvalue is set to the predecessor of the greatest
+ * multiple of dist less or equal 2^32. */
+ guint32 maxvalue;
+ if (dist <= 0x80000000u) /* 2^31 */
{
- border <<= 1;
- right_shift--;
+ /* maxvalue = 2^32 - 1 - (2^32 % dist) */
+ guint32 leftover = (0x80000000u % dist) * 2;
+ if (leftover >= dist) leftover -= dist;
+ maxvalue = 0xffffffffu - leftover;
}
+ else
+ maxvalue = dist - 1;
+
+ do
+ random = g_rand_int (rand);
+ while (random > maxvalue);
+
+ random %= dist;
}
- do
- {
- random = g_rand_int (rand) >> right_shift;
- } while (random >= dist);
- }
- return min + random;
+ break;
+ default:
+ random = 0; /* Quiet GCC */
+ g_assert_not_reached ();
+ }
+
+ return begin + random;
}
-/* transform [0..2^32-1] -> [0..1) */
-#define G_RAND_DOUBLE_TRANSFORM 2.3283064365386963e-10
-
/**
* g_rand_double:
- * @rand: a #GRand.
+ * @rand_: a #GRand.
*
- * Return the next random #gdouble from @rand equaly distributed over
+ * Returns the next random #gdouble from @rand_ equally distributed over
* the range [0..1).
*
* Return value: A random number.
**/
gdouble
g_rand_double (GRand* rand)
-{
- return g_rand_int (rand) * G_RAND_DOUBLE_TRANSFORM;
+{
+ /* 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.
- * @min: lower closed bound of the interval.
- * @max: upper open bound of the interval.
+ * @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 [@min..@max).
+ * Returns the next random #gdouble from @rand_ equally distributed over
+ * the range [@begin..@end).
*
* Return value: A random number.
**/
gdouble
-g_rand_double_range (GRand* rand, gdouble min, gdouble max)
+g_rand_double_range (GRand* rand, gdouble begin, gdouble end)
{
- return g_rand_int (rand) * ((max - min) * G_RAND_DOUBLE_TRANSFORM) + min;
+ return g_rand_double (rand) * (end - begin) + begin;
}
/**
* g_random_int:
*
- * Return a random #guint32 equaly distributed over the range
+ * Return a random #guint32 equally distributed over the range
* [0..2^32-1].
*
* Return value: A random number.
/**
* g_random_int_range:
- * @min: lower closed bound of the interval.
- * @max: upper open bound of the interval.
+ * @begin: lower closed bound of the interval.
+ * @end: upper open bound of the interval.
*
- * Return a random #gint32 equaly distributed over the range
- * [@min..@max-1].
+ * Returns a random #gint32 equally distributed over the range
+ * [@begin..@end-1].
*
* Return value: A random number.
**/
gint32
-g_random_int_range (gint32 min, gint32 max)
+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, min, max);
+ 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).
+ * Returns a random #gdouble equally distributed over the range [0..1).
*
* Return value: A random number.
**/
/**
* g_random_double_range:
- * @min: lower closed bound of the interval.
- * @max: upper open bound of the interval.
+ * @begin: lower closed bound of the interval.
+ * @end: upper open bound of the interval.
*
- * Return a random #gdouble equaly distributed over the range [@min..@max).
+ * Returns a random #gdouble equally distributed over the range [@begin..@end).
*
* Return value: A random number.
**/
gdouble
-g_random_double_range (gdouble min, gdouble max)
+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, min, max);
+ result = g_rand_double_range (global_random, begin, end);
G_UNLOCK (global_random);
return result;
}
* @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.
+ * by the <function>g_random_*</function> functions, to @seed.
**/
void
g_random_set_seed (guint32 seed)
projects / platform / upstream / glib.git / blobdiff