#endif
+
+
+static void
+scramble_seed (unsigned char *dest, unsigned char *src, int size)
+{
+ int i;
+
+ for (i = 0; i < size; i++)
+ dest[(i % 2) * (size / 2) + i / 2] = src[i];
+}
+
+
+static void
+unscramble_seed (unsigned char *dest, unsigned char *src, int size)
+{
+ int i;
+
+ for (i = 0; i < size; i++)
+ dest[i] = src[(i % 2) * (size / 2) + i / 2];
+}
+
+
+
/* random_seed is used to seed the PRNG with either a default
set of seeds or user specified set of seeds. random_seed
must be called with no argument or exactly one argument. */
random_seed_i4 (GFC_INTEGER_4 *size, gfc_array_i4 *put, gfc_array_i4 *get)
{
int i;
+ unsigned char seed[4*kiss_size];
__gthread_mutex_lock (&random_lock);
if (((put->dim[0].ubound + 1 - put->dim[0].lbound)) < kiss_size)
runtime_error ("Array size of PUT is too small.");
- /* This code now should do correct strides. */
+ /* We copy the seed given by the user. */
for (i = 0; i < kiss_size; i++)
- kiss_seed[i] = (GFC_UINTEGER_4) put->data[i * put->dim[0].stride];
+ memcpy (seed + i * sizeof(GFC_UINTEGER_4),
+ &(put->data[(kiss_size - 1 - i) * put->dim[0].stride]),
+ sizeof(GFC_UINTEGER_4));
+
+ /* We put it after scrambling the bytes, to paper around users who
+ provide seeds with quality only in the lower or upper part. */
+ scramble_seed ((unsigned char *) kiss_seed, seed, 4*kiss_size);
}
/* Return the seed to GET data. */
if (((get->dim[0].ubound + 1 - get->dim[0].lbound)) < kiss_size)
runtime_error ("Array size of GET is too small.");
- /* This code now should do correct strides. */
+ /* Unscramble the seed. */
+ unscramble_seed (seed, (unsigned char *) kiss_seed, 4*kiss_size);
+
+ /* Then copy it back to the user variable. */
for (i = 0; i < kiss_size; i++)
- get->data[i * get->dim[0].stride] = (GFC_INTEGER_4) kiss_seed[i];
+ memcpy (&(get->data[(kiss_size - 1 - i) * get->dim[0].stride]),
+ seed + i * sizeof(GFC_UINTEGER_4),
+ sizeof(GFC_UINTEGER_4));
}
__gthread_mutex_unlock (&random_lock);