--- deliantra/server/include/rng.h	2010/07/06 20:00:46	1.2
+++ deliantra/server/include/rng.h	2012/05/17 02:20:45	1.10
@@ -1,7 +1,7 @@
 /*
  * This file is part of Deliantra, the Roguelike Realtime MMORPG.
  * 
- * Copyright (©) 2010 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
+ * Copyright (©) 2010,2011,2012 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
  * 
  * Deliantra is free software: you can redistribute it and/or modify it under
  * the terms of the Affero GNU General Public License as published by the
@@ -25,10 +25,12 @@
 
 #include <compiler.h>
 
+typedef uint32_t seed_t; // overkill
+
 // 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
+struct tausworthe_rng
 {
   uint32_t state [4];
 
@@ -41,13 +43,13 @@
 // 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.
 // see also http://www.iro.umontreal.ca/~lecuyer/myftp/papers/xorshift.pdf
-struct xorshift_random_generator
+struct xorshift_rng
 {
   uint32_t x, y;
 
   void seed (uint32_t seed)
   {
-    x = seed | 1;
+    x = seed ? seed : 0xdeadbeef;
     y = x * 69069U;
   }
 
@@ -60,8 +62,30 @@
   }
 };
 
+template<uint32_t A, uint32_t B>
+struct lc_rng
+{
+  uint32_t x;
+
+  void seed (uint32_t seed)
+  {
+    x = seed;
+  }
+
+  uint32_t next ()
+  {
+    x = x * A + B;
+    return x;
+  }
+};
+
+typedef lc_rng<3039177861U,          0U> borosh_niederreiter_rng;
+typedef lc_rng<2147001325U,  715136305U> bcpl_rng;
+typedef lc_rng<   1664525U,          1U> lavaux_janssens_rng;
+typedef lc_rng<   1664525U, 1013904223U> numerical_recipes_rng;
+
 template<typename T, int N, int k>
-struct gfsr_random_generator
+struct gfsr_rng
 {
   int i;
   T x[N];
@@ -87,9 +111,9 @@
   }
 
   // actually should subclass to gfsr32... :)
-  void seed (uint32_t seed)
+  void seed (seed_t seed)
   {
-    xorshift_random_generator rng;
+    xorshift_rng rng;
 
     rng.seed (seed);
     this->seed_rng (rng);
@@ -112,24 +136,27 @@
 
 // these are about 2-3 times faster than tausworthe, non-inlined,
 // and likely of higher quality.
-typedef gfsr_random_generator<uint32_t, 250, 103> r250_random_generator;
-typedef gfsr_random_generator<uint32_t, 521, 168> r521_random_generator;
+typedef gfsr_rng<uint32_t, 250, 103> r250_rng;
+typedef gfsr_rng<uint32_t, 521, 168> r521_rng;
 
 // freeciv uses this one, so it's good enough for us :)
-typedef gfsr_random_generator<uint32_t,  55,  24> freeciv_random_generator;
+// (also known as mitchell moore generator
+typedef gfsr_rng<uint32_t,  55,  24> freeciv_rng;
 
 // this one should be high quality, but is slightly slower than tausworthe
-struct r250521_random_generator
+struct r250521_rng
 {
-  r250_random_generator r250;
-  r521_random_generator r521;
+  r250_rng r250;
+  r521_rng r521;
 
   void seed (uint32_t seed);
   uint32_t next ();
 };
 
-// this is actually an adaptor that provides different types
-// of random numbers.
+/////////////////////////////////////////////////////////////////////////////
+
+// this is actually an adaptor that provides different
+// distributions of random numbers.
 template<class generator>
 struct random_number_generator : generator
 {
@@ -137,7 +164,7 @@
   {
   }
 
-  random_number_generator (uint32_t seed)
+  random_number_generator (seed_t seed)
   {
     this->seed (seed);
   }
@@ -158,14 +185,18 @@
               : get_range (r_min, r_max);
   }
 
+  uint32_t get_u32 ();
+  uint64_t get_u64 ();
+  float    get_float ();
+  double   get_double ();
+
   // return a number within the half-open interval [0..1[
-  double operator ()()
+  double operator () ()
   {
-    return this->next () / (double)0x100000000ULL;
+    return get_double ();
   }
 
-  uint32_t get_u32 ();
-  uint64_t get_u64 ();
+  uint32_t poisson (double mean);
 
 protected:
   uint32_t get_range (uint32_t r_max);
@@ -173,10 +204,10 @@
 };
 
 // the default rng used in the game
-typedef random_number_generator<freeciv_random_generator> rand_gen;
+typedef random_number_generator<freeciv_rng> rand_gen;
 
 // used when we often seed
-typedef random_number_generator<tausworthe_random_generator> seedable_rand_gen;
+typedef random_number_generator<tausworthe_rng> seedable_rand_gen;
 
 extern rand_gen rndm, rmg_rndm;