server/include/rng.h

/*
 * This file is part of Deliantra, the Roguelike Realtime MMORPG.
 * 
 * Copyright (©) 2010,2011 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
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the Affero GNU General Public License
 * and the GNU General Public License along with this program. If not, see
 * <http://www.gnu.org/licenses/>.
 * 
 * The authors can be reached via e-mail to <support@deliantra.net>
 */

#ifndef RNG_H__
#define RNG_H__

#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_rng
{
  uint32_t state [4];

  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.
// see also http://www.iro.umontreal.ca/~lecuyer/myftp/papers/xorshift.pdf
struct xorshift_rng
{
  uint32_t x, y;

  void seed (uint32_t seed)
  {
    x = seed ? seed : 0xdeadbeef;
    y = x * 69069U;
  }

  uint32_t next ()
  {
    uint32_t t = x ^ (x << 10);
    x = y;
    y = y ^ (y >> 13) ^ t ^ (t >> 10);
    return y;
  }
};

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;

template<typename T, int N, int k>
struct gfsr_rng
{
  int i;
  T x[N];

  // rng must have same bitwidth as T
  template<typename RNG>
  void seed_rng (RNG rng)
  {
    i = N;

    do
      x [--i] = rng.next ();
    while (i > sizeof (T) * 8);

    T m = 1;

    do
      {
        x [--i] = (rng.next () | m) & ~(m - 1);
        m <<= 1;
      }
    while (i);
  }

  // actually should subclass to gfsr32... :)
  void seed (seed_t seed)
  {
    xorshift_rng rng;

    rng.seed (seed);
    this->seed_rng (rng);
  }

  T next ()
  {
    int j = i + (k - N);

    if (j < 0)
      j += N;

    T v = (x [i] ^= x [j]);

    i = (i ? i : N) - 1;

    return v;
  }
};

// these are about 2-3 times faster than tausworthe, non-inlined,
// and likely of higher quality.
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 :)
// (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_rng
{
  r250_rng r250;
  r521_rng r521;

  void seed (uint32_t seed);
  uint32_t next ();
};

/////////////////////////////////////////////////////////////////////////////

// this is actually an adaptor that provides different
// distributions of random numbers.
template<class generator>
struct random_number_generator : generator
{
  random_number_generator ()
  {
  }

  random_number_generator (seed_t seed)
  {
    this->seed (seed);
  }

  // uniform distribution, [0 .. num - 1]
  uint32_t operator ()(uint32_t num)
  {
    return !is_constant (num) ? get_range (num)                        // non-constant
         : num & (num - 1)    ? (this->next () * (uint64_t)num) >> 32U // constant, non-power-of-two
         :                      this->next () & (num - 1);             // constant, power-of-two
  }

  // return a number within the closed interval [min .. max], max can be >, < or == min.
  int operator () (int r_min, int r_max)
  {
    return is_constant (r_min <= r_max) && r_min <= r_max
              ? r_min + operator ()(r_max - r_min + 1)
              : 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 () ()
  {
    return get_double ();
  }

  uint32_t poisson (double mean);

protected:
  uint32_t get_range (uint32_t r_max);
  int get_range (int r_min, int r_max);
};

// the default rng used in the game
typedef random_number_generator<freeciv_rng> rand_gen;

// used when we often seed
typedef random_number_generator<tausworthe_rng> seedable_rand_gen;

extern rand_gen rndm, rmg_rndm;

#endif

Revision:	1.8
Committed:	Sat Apr 30 11:02:25 2011 UTC (13 years ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.7:	+5 -1 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	/*
2			* This file is part of Deliantra, the Roguelike Realtime MMORPG.
3			*
4	root	1.6	* Copyright (©) 2010,2011 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
5	root	1.1	*
6			* Deliantra is free software: you can redistribute it and/or modify it under
7			* the terms of the Affero GNU General Public License as published by the
8			* Free Software Foundation, either version 3 of the License, or (at your
9			* option) any later version.
10			*
11			* This program is distributed in the hope that it will be useful,
12			* but WITHOUT ANY WARRANTY; without even the implied warranty of
13			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14			* GNU General Public License for more details.
15			*
16			* You should have received a copy of the Affero GNU General Public License
17			* and the GNU General Public License along with this program. If not, see
18			* <http://www.gnu.org/licenses/>.
19			*
20			* The authors can be reached via e-mail to <support@deliantra.net>
21			*/
22
23			#ifndef RNG_H__
24			#define RNG_H__
25
26			#include <compiler.h>
27
28	root	1.7	typedef uint32_t seed_t; // overkill
29
30	root	1.1	// P. L'Ecuyer, “Maximally Equidistributed Combined Tausworthe Generators”, Mathematics of Computation, 65, 213 (1996), 203–213.
31			// http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
32			// http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
33	root	1.3	struct tausworthe_rng
34	root	1.1	{
35			uint32_t state [4];
36
37			void seed (uint32_t seed);
38			uint32_t next ();
39			};
40
41			// Xorshift RNGs, George Marsaglia
42			// http://www.jstatsoft.org/v08/i14/paper
43			// this one is about 40% faster than the tausworthe one above (i.e. not much),
44			// despite the inlining, and has the issue of only creating 2**32-1 numbers.
45			// see also http://www.iro.umontreal.ca/~lecuyer/myftp/papers/xorshift.pdf
46	root	1.3	struct xorshift_rng
47	root	1.1	{
48			uint32_t x, y;
49
50			void seed (uint32_t seed)
51			{
52	root	1.4	x = seed ? seed : 0xdeadbeef;
53	root	1.1	y = x * 69069U;
54			}
55
56			uint32_t next ()
57			{
58			uint32_t t = x ^ (x << 10);
59			x = y;
60			y = y ^ (y >> 13) ^ t ^ (t >> 10);
61			return y;
62			}
63			};
64
65	root	1.3	template<uint32_t A, uint32_t B>
66			struct lc_rng
67			{
68			uint32_t x;
69
70			void seed (uint32_t seed)
71			{
72			x = seed;
73			}
74
75			uint32_t next ()
76			{
77			x = x * A + B;
78			return x;
79			}
80			};
81
82	root	1.8	typedef lc_rng<3039177861U, 0U> borosh_niederreiter_rng;
83	root	1.3	typedef lc_rng<2147001325U, 715136305U> bcpl_rng;
84	root	1.8	typedef lc_rng< 1664525U, 1U> lavaux_janssens_rng;
85	root	1.3
86	root	1.1	template<typename T, int N, int k>
87	root	1.3	struct gfsr_rng
88	root	1.1	{
89			int i;
90			T x[N];
91
92			// rng must have same bitwidth as T
93			template<typename RNG>
94			void seed_rng (RNG rng)
95			{
96			i = N;
97
98			do
99			x [--i] = rng.next ();
100			while (i > sizeof (T) * 8);
101
102			T m = 1;
103
104			do
105			{
106			x [--i] = (rng.next () \| m) & ~(m - 1);
107			m <<= 1;
108			}
109			while (i);
110			}
111
112			// actually should subclass to gfsr32... :)
113	root	1.7	void seed (seed_t seed)
114	root	1.1	{
115	root	1.3	xorshift_rng rng;
116	root	1.1
117			rng.seed (seed);
118			this->seed_rng (rng);
119			}
120
121			T next ()
122			{
123			int j = i + (k - N);
124
125			if (j < 0)
126			j += N;
127
128			T v = (x [i] ^= x [j]);
129
130			i = (i ? i : N) - 1;
131
132			return v;
133			}
134			};
135
136			// these are about 2-3 times faster than tausworthe, non-inlined,
137			// and likely of higher quality.
138	root	1.3	typedef gfsr_rng<uint32_t, 250, 103> r250_rng;
139			typedef gfsr_rng<uint32_t, 521, 168> r521_rng;
140	root	1.1
141			// freeciv uses this one, so it's good enough for us :)
142	root	1.8	// (also known as mitchell moore generator
143	root	1.3	typedef gfsr_rng<uint32_t, 55, 24> freeciv_rng;
144	root	1.1
145			// this one should be high quality, but is slightly slower than tausworthe
146	root	1.3	struct r250521_rng
147	root	1.1	{
148	root	1.3	r250_rng r250;
149			r521_rng r521;
150	root	1.1
151			void seed (uint32_t seed);
152			uint32_t next ();
153			};
154
155	root	1.8	/////////////////////////////////////////////////////////////////////////////
156
157	root	1.5	// this is actually an adaptor that provides different
158			// distributions of random numbers.
159	root	1.1	template<class generator>
160			struct random_number_generator : generator
161			{
162	root	1.2	random_number_generator ()
163			{
164			}
165
166	root	1.7	random_number_generator (seed_t seed)
167	root	1.2	{
168			this->seed (seed);
169			}
170
171	root	1.1	// uniform distribution, [0 .. num - 1]
172			uint32_t operator ()(uint32_t num)
173			{
174			return !is_constant (num) ? get_range (num) // non-constant
175			: num & (num - 1) ? (this->next () * (uint64_t)num) >> 32U // constant, non-power-of-two
176			: this->next () & (num - 1); // constant, power-of-two
177			}
178
179			// return a number within the closed interval [min .. max], max can be >, < or == min.
180			int operator () (int r_min, int r_max)
181			{
182			return is_constant (r_min <= r_max) && r_min <= r_max
183			? r_min + operator ()(r_max - r_min + 1)
184			: get_range (r_min, r_max);
185			}
186
187	root	1.3	uint32_t get_u32 ();
188			uint64_t get_u64 ();
189			float get_float ();
190			double get_double ();
191
192	root	1.1	// return a number within the half-open interval [0..1[
193	root	1.3	double operator () ()
194	root	1.1	{
195	root	1.3	return get_double ();
196	root	1.1	}
197
198	root	1.3	uint32_t poisson (double mean);
199	root	1.1
200			protected:
201			uint32_t get_range (uint32_t r_max);
202			int get_range (int r_min, int r_max);
203			};
204
205			// the default rng used in the game
206	root	1.3	typedef random_number_generator<freeciv_rng> rand_gen;
207	root	1.1
208	root	1.2	// used when we often seed
209	root	1.3	typedef random_number_generator<tausworthe_rng> seedable_rand_gen;
210	root	1.2
211	root	1.1	extern rand_gen rndm, rmg_rndm;
212
213			#endif
214