Add the init_by_array functionality from the reference implementation of

Fri Dec 19 11:49:21 2003  George Lebl <jirka@5z.com>

        * glib/grand.c
          glib/grand.h (g_rand_new) (g_rand_new_with_seed)
          (g_rand_new_with_seed_array) (g_rand_set_seed_array):  Add
          the init_by_array functionality from the reference implementation
          of the mersenne twister (mt19937ar.c) and change the naming
          to fit with the rest of the grand API.  New functions are
          g_rand_new_with_seed_array, g_rand_set_seed_array.  This is only
          reliable/tested for the 2.2 version of the seeding as that's what
          the reference implementation uses.  Also modify g_rand_new to
          get 4 longs from /dev/urandom since that will always be available
          anyway and we get more entropy and if /dev/urandom is unavailable
          use also 4 longs for seeding using secs, usecs, getpid and getppid.
          For version 2.0 use only a simple seed again but be more careful
          about seeding with secs/usecs in this case.

        * glib/grand.c
          glib/grand.h (g_rand_copy):  Add g_rand_copy function to copy the
          current state of the random number generator.

        * glib/grand.c (g_rand_new):  Add testing for EINTR when reading
          from /dev/urandom

        * tests/rand-test.c: add testing of the array seeding stuff against
          the reference implementation, plus add statistical sanity check
          to see that the values outputted are truly kind of random.  And
          check that g_rand_copy truly copies the state by checking a few
          terms.

1 files changed, 59 insertions, 1 deletions

diff --git a/tests/rand-test.c b/tests/rand-test.c
index c8efa21c5..141883eb8 100644
--- a/tests/rand-test.c
+++ b/tests/rand-test.c
@@ -3,7 +3,11 @@
 
 #include <glib.h>
 
-const gint32 first_numbers[] = 
+/* Outputs tested against the reference implementation mt19937ar.c from
+   http://www.math.keio.ac.jp/~matumoto/MT2002/emt19937ar.html */
+
+/* Tests for a simple seed, first number is the seed */
+const guint32 first_numbers[] = 
 {
   0x7a7a7a7a,
   0xfdcc2d54,
@@ -28,17 +32,56 @@ const gint32 first_numbers[] =
   0x1696330c,
 };
 
+/* array seed */
+const guint32 seed_array[] =
+{
+  0x6553375f,
+  0xd6b8d43b,
+  0xa1e7667f,
+  0x2b10117c
+};
+
+/* tests for the array seed */
+const guint32 array_outputs[] =
+{
+  0xc22b7dc3,
+  0xfdecb8ae,
+  0xb4af0738,
+  0x516bc6e1,
+  0x7e372e91,
+  0x2d38ff80,
+  0x6096494a,
+  0xd162d5a8,
+  0x3c0aaa0d,
+  0x10e736ae
+};
+
 const gint length = sizeof (first_numbers) / sizeof (first_numbers[0]);
+const gint seed_length = sizeof (seed_array) / sizeof (seed_array[0]);
+const gint array_length = sizeof (array_outputs) / sizeof (array_outputs[0]);
 
 int main()
 {
   guint n;
+  guint ones;
+  double proportion;
 
   GRand* rand = g_rand_new_with_seed (first_numbers[0]);
+  GRand* copy;
 
   for (n = 1; n < length; n++)
     g_assert (first_numbers[n] == g_rand_int (rand));
 
+  g_rand_set_seed (rand, 2);
+  g_rand_set_seed_array (rand, seed_array, seed_length);
+
+  for (n = 0; n < array_length; n++)
+    g_assert (array_outputs[n] == g_rand_int (rand));
+
+  copy = g_rand_copy (rand);
+  for (n = 0; n < 100; n++)
+    g_assert (g_rand_int (copy) == g_rand_int (rand));
+
   for (n = 1; n < 100000; n++)
     {
       gint32 i;
@@ -70,7 +113,22 @@ int main()
       g_assert (b == TRUE || b  == FALSE);     
     }
 
+  /* Statistical sanity check, count the number of ones
+   * when getting random numbers in range [0,3) and see
+   * that it must be semi-close to 0.25 with a VERY large
+   * probability */
+  ones = 0;
+  for (n = 1; n < 100000; n++)
+    {
+      if (g_random_int_range (0, 4) == 1)
+        ones ++;
+    }
+  proportion = (double)ones / (double)100000;
+  /* 0.025 is overkill, but should suffice to test for some unreasonability */
+  g_assert (ABS (proportion - 0.25) < 0.025);
+
   g_rand_free (rand);
+  g_rand_free (copy);
 
   return 0;
 }