Merge remote branch 'gvdb/master'

[platform/upstream/glib.git] / glib / grand.c

diff --git a/glib/grand.c b/glib/grand.c
index c4ea8ee..231ed13 100644 (file)
--- a/glib/grand.c
+++ b/glib/grand.c
@@ -21,7 +21,7 @@
  * Nishimura.  Please mail <matumoto@math.keio.ac.jp>, 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
+ * http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
  * This code was adapted to glib by Sebastian Wilhelmi.
  */
 
@@ -48,13 +48,63 @@
 #endif
 
 #include "glib.h"
-#include "gthreadinit.h"
+#include "gthreadprivate.h"
 #include "galias.h"
 
 #ifdef G_OS_WIN32
 #include <process.h>           /* For getpid() */
 #endif
 
+/**
+ * SECTION: random_numbers
+ * @title: Random Numbers
+ * @short_description: pseudo-random number generator
+ *
+ * The following functions allow you to use a portable, fast and good
+ * pseudo-random number generator (PRNG). It uses the Mersenne Twister
+ * PRNG, which was originally developed by Makoto Matsumoto and Takuji
+ * Nishimura. Further information can be found at
+ * <ulink url="http://www.math.keio.ac.jp/~matumoto/emt.html">
+ * www.math.keio.ac.jp/~matumoto/emt.html</ulink>.
+ *
+ * If you just need a random number, you simply call the
+ * <function>g_random_*</function> functions, which will create a
+ * globally used #GRand and use the according
+ * <function>g_rand_*</function> functions internally. Whenever you
+ * need a stream of reproducible random numbers, you better create a
+ * #GRand yourself and use the <function>g_rand_*</function> functions
+ * directly, which will also be slightly faster. Initializing a #GRand
+ * with a certain seed will produce exactly the same series of random
+ * numbers on all platforms. This can thus be used as a seed for e.g.
+ * games.
+ *
+ * The <function>g_rand*_range</function> functions will return high
+ * quality equally distributed random numbers, whereas for example the
+ * <literal>(g_random_int()&percnt;max)</literal> approach often
+ * doesn't yield equally distributed numbers.
+ *
+ * GLib changed the seeding algorithm for the pseudo-random number
+ * generator Mersenne Twister, as used by
+ * <structname>GRand</structname> and <structname>GRandom</structname>.
+ * This was necessary, because some seeds would yield very bad
+ * pseudo-random streams.  Also the pseudo-random integers generated by
+ * <function>g_rand*_int_range()</function> will have a slightly better
+ * equal distribution with the new version of GLib.
+ *
+ * The original seeding and generation algorithms, as found in GLib
+ * 2.0.x, can be used instead of the new ones by setting the
+ * environment variable <envar>G_RANDOM_VERSION</envar> to the value of
+ * '2.0'. Use the GLib-2.0 algorithms only if you have sequences of
+ * numbers generated with Glib-2.0 that you need to reproduce exactly.
+ **/
+
+/**
+ * GRand:
+ *
+ * The #GRand struct is an opaque data structure. It should only be
+ * accessed through the <function>g_rand_*</function> functions.
+ **/
+
 G_LOCK_DEFINE_STATIC (global_random);
 static GRand* global_random = NULL;
 
@@ -181,6 +231,7 @@ g_rand_new (void)
        {
          int r;
 
+         setvbuf (dev_urandom, NULL, _IONBF, 0);
          do
            {
              errno = 0;
@@ -191,12 +242,7 @@ g_rand_new (void)
          if (r != 1)
            dev_urandom_exists = FALSE;
 
-         do
-           {
-             errno = 0;
-             fclose (dev_urandom);
-           }
-         while G_UNLIKELY (errno == EINTR);
+         fclose (dev_urandom);
        }       
       else
        dev_urandom_exists = FALSE;
@@ -362,6 +408,14 @@ g_rand_set_seed_array (GRand* rand, const guint32 *seed, guint seed_length)
 }
 
 /**
+ * g_rand_boolean:
+ * @rand_: a #GRand.
+ * @Returns: a random #gboolean.
+ *
+ * Returns a random #gboolean from @rand_. This corresponds to a
+ * unbiased coin toss.
+ **/
+/**
  * g_rand_int:
  * @rand_: a #GRand.
  *
@@ -532,6 +586,12 @@ g_rand_double_range (GRand* rand, gdouble begin, gdouble end)
 }
 
 /**
+ * g_random_boolean:
+ * @Returns: a random #gboolean.
+ *
+ * Returns a random #gboolean. This corresponds to a unbiased coin toss.
+ **/
+/**
  * g_random_int:
  *
  * Return a random #guint32 equally distributed over the range