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 (13 years, 1 month ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.6:	+4 -2 lines
Log Message:	* empty log message *
#	Content
1	/*
2	* This file is part of Deliantra, the Roguelike Realtime MMORPG.
3	*
4	* Copyright (©) 2010,2011 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
5	*
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	typedef uint32_t seed_t; // overkill
29
30	// 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	struct tausworthe_rng
34	{
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	struct xorshift_rng
47	{
48	uint32_t x, y;
49
50	void seed (uint32_t seed)
51	{
52	x = seed ? seed : 0xdeadbeef;
53	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	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	template<typename T, int N, int k>
86	struct gfsr_rng
87	{
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	void seed (seed_t seed)
113	{
114	xorshift_rng rng;
115
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	typedef gfsr_rng<uint32_t, 250, 103> r250_rng;
138	typedef gfsr_rng<uint32_t, 521, 168> r521_rng;
139
140	// freeciv uses this one, so it's good enough for us :)
141	typedef gfsr_rng<uint32_t, 55, 24> freeciv_rng;
142
143	// this one should be high quality, but is slightly slower than tausworthe
144	struct r250521_rng
145	{
146	r250_rng r250;
147	r521_rng r521;
148
149	void seed (uint32_t seed);
150	uint32_t next ();
151	};
152
153	// this is actually an adaptor that provides different
154	// distributions of random numbers.
155	template<class generator>
156	struct random_number_generator : generator
157	{
158	random_number_generator ()
159	{
160	}
161
162	random_number_generator (seed_t seed)
163	{
164	this->seed (seed);
165	}
166
167	// 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	uint32_t get_u32 ();
184	uint64_t get_u64 ();
185	float get_float ();
186	double get_double ();
187
188	// return a number within the half-open interval [0..1[
189	double operator () ()
190	{
191	return get_double ();
192	}
193
194	uint32_t poisson (double mean);
195
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	typedef random_number_generator<freeciv_rng> rand_gen;
203
204	// used when we often seed
205	typedef random_number_generator<tausworthe_rng> seedable_rand_gen;
206
207	extern rand_gen rndm, rmg_rndm;
208
209	#endif
210