[ViewVC] Diff of: cvs/deliantra/server/include/util.h

Comparing deliantra/server/include/util.h (file contents):
Revision 1.82 by root, Sat Dec 27 02:33:32 2008 UTC vs.
Revision 1.83 by root, Tue Dec 30 07:24:16 2008 UTC

 // P. L'Ecuyer, “Maximally Equidistributed Combined Tausworthe Generators”, Mathematics of Computation, 65, 213 (1996), 203–213.
 // http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
 // http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
 struct tausworthe_random_generator
 {
-  // generator
   uint32_t state [4];
   void operator =(const tausworthe_random_generator &src)
   {
     state [0] = src.state [0];
     state [3] = src.state [3];
   }
   void seed (uint32_t seed);
   uint32_t next ();
+};
+// Xorshift RNGs, George Marsaglia
+// http://www.jstatsoft.org/v08/i14/paper
+// this one is about 40% faster than the tausworthe one above (i.e. not much),
+// despite the inlining, and has the issue of only creating 2**32-1 numbers.
+struct xorshift_random_generator
+{
+  uint32_t x, y;
+  void operator =(const xorshift_random_generator &src)
+  {
+    x = src.x;
+    y = src.y;
+  }
+  void seed (uint32_t seed)
+  {
+    x = seed;
+    y = seed * 69069U;
+  }
+  uint32_t next ()
+  {
+    uint32_t t = x ^ (x << 10);
+    x = y;
+    y = y ^ (y >> 13) ^ t ^ (t >> 10);
+    return y;
+  }
+};
+template<class generator>
+struct random_number_generator : generator
+{
   // uniform distribution, 0 .. max (0, num - 1)
   uint32_t operator ()(uint32_t num)
   {
-    return !is_constant (num) ? get_range (num)                  // non-constant
+    return !is_constant (num) ? get_range (num)                        // non-constant
-         : num & (num - 1)    ? (next () * (uint64_t)num) >> 32U // constant, non-power-of-two
+         : num & (num - 1)    ? (this->next () * (uint64_t)num) >> 32U // constant, non-power-of-two
-         :                      next () & (num - 1);             // constant, power-of-two
+         :                      this->next () & (num - 1);             // constant, power-of-two
   }
   // return a number within (min .. max)
   int operator () (int r_min, int r_max)
   {
 protected:
   uint32_t get_range (uint32_t r_max);
   int get_range (int r_min, int r_max);
 };
-typedef tausworthe_random_generator rand_gen;
+typedef random_number_generator<tausworthe_random_generator> rand_gen;
 extern rand_gen rndm, rmg_rndm;
 INTERFACE_CLASS (attachable)
 struct refcnt_base

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing deliantra/server/include/util.h (file contents): Revision 1.82 by root, Sat Dec 27 02:33:32 2008 UTC vs. Revision 1.83 by root, Tue Dec 30 07:24:16 2008 UTC

Diff Legend

Comparing deliantra/server/include/util.h (file contents):
Revision 1.82 by root, Sat Dec 27 02:33:32 2008 UTC vs.
Revision 1.83 by root, Tue Dec 30 07:24:16 2008 UTC