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, 0> borosh_niederreiter_rng;
typedef lc_rng<2147001325U, 715136305U> bcpl_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 :)
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:	1.7
Committed:	Tue Apr 26 14:41:36 2011 UTC (15 years, 5 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.6:	+4 -2 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			typedef lc_rng<3039177861U, 0> borosh_niederreiter_rng;
83			typedef lc_rng<2147001325U, 715136305U> bcpl_rng;
84
85	root	1.1	template<typename T, int N, int k>
86	root	1.3	struct gfsr_rng
87	root	1.1	{
88			int i;
89			T x[N];
90
91			// rng must have same bitwidth as T
92			template<typename RNG>
93			void seed_rng (RNG rng)
94			{
95			i = N;
96
97			do
98			x [--i] = rng.next ();
99			while (i > sizeof (T) * 8);
100
101			T m = 1;
102
103			do
104			{
105			x [--i] = (rng.next () \| m) & ~(m - 1);
106			m <<= 1;
107			}
108			while (i);
109			}
110
111			// actually should subclass to gfsr32... :)
112	root	1.7	void seed (seed_t seed)
113	root	1.1	{
114	root	1.3	xorshift_rng rng;
115	root	1.1
116			rng.seed (seed);
117			this->seed_rng (rng);
118			}
119
120			T next ()
121			{
122			int j = i + (k - N);
123
124			if (j < 0)
125			j += N;
126
127			T v = (x [i] ^= x [j]);
128
129			i = (i ? i : N) - 1;
130
131			return v;
132			}
133			};
134
135			// these are about 2-3 times faster than tausworthe, non-inlined,
136			// and likely of higher quality.
137	root	1.3	typedef gfsr_rng<uint32_t, 250, 103> r250_rng;
138			typedef gfsr_rng<uint32_t, 521, 168> r521_rng;
139	root	1.1
140			// freeciv uses this one, so it's good enough for us :)
141	root	1.3	typedef gfsr_rng<uint32_t, 55, 24> freeciv_rng;
142	root	1.1
143			// this one should be high quality, but is slightly slower than tausworthe
144	root	1.3	struct r250521_rng
145	root	1.1	{
146	root	1.3	r250_rng r250;
147			r521_rng r521;
148	root	1.1
149			void seed (uint32_t seed);
150			uint32_t next ();
151			};
152
153	root	1.5	// this is actually an adaptor that provides different
154			// distributions of random numbers.
155	root	1.1	template<class generator>
156			struct random_number_generator : generator
157			{
158	root	1.2	random_number_generator ()
159			{
160			}
161
162	root	1.7	random_number_generator (seed_t seed)
163	root	1.2	{
164			this->seed (seed);
165			}
166
167	root	1.1	// uniform distribution, [0 .. num - 1]
168			uint32_t operator ()(uint32_t num)
169			{
170			return !is_constant (num) ? get_range (num) // non-constant
171			: num & (num - 1) ? (this->next () * (uint64_t)num) >> 32U // constant, non-power-of-two
172			: this->next () & (num - 1); // constant, power-of-two
173			}
174
175			// return a number within the closed interval [min .. max], max can be >, < or == min.
176			int operator () (int r_min, int r_max)
177			{
178			return is_constant (r_min <= r_max) && r_min <= r_max
179			? r_min + operator ()(r_max - r_min + 1)
180			: get_range (r_min, r_max);
181			}
182
183	root	1.3	uint32_t get_u32 ();
184			uint64_t get_u64 ();
185			float get_float ();
186			double get_double ();
187
188	root	1.1	// return a number within the half-open interval [0..1[
189	root	1.3	double operator () ()
190	root	1.1	{
191	root	1.3	return get_double ();
192	root	1.1	}
193
194	root	1.3	uint32_t poisson (double mean);
195	root	1.1
196			protected:
197			uint32_t get_range (uint32_t r_max);
198			int get_range (int r_min, int r_max);
199			};
200
201			// the default rng used in the game
202	root	1.3	typedef random_number_generator<freeciv_rng> rand_gen;
203	root	1.1
204	root	1.2	// used when we often seed
205	root	1.3	typedef random_number_generator<tausworthe_rng> seedable_rand_gen;
206	root	1.2
207	root	1.1	extern rand_gen rndm, rmg_rndm;
208
209			#endif
210