server/include/rng.h

/*
 * This file is part of Deliantra, the Roguelike Realtime MMORPG.
 * 
 * Copyright (©) 2010 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>

// 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
{
  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_random_generator
{
  uint32_t x, y;

  void seed (uint32_t seed)
  {
    x = seed | 1;
    y = x * 69069U;
  }

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

template<typename T, int N, int k>
struct gfsr_random_generator
{
  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 (uint32_t seed)
  {
    xorshift_random_generator 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_random_generator<uint32_t, 250, 103> r250_random_generator;
typedef gfsr_random_generator<uint32_t, 521, 168> r521_random_generator;

// freeciv uses this one, so it's good enough for us :)
typedef gfsr_random_generator<uint32_t,  55,  24> freeciv_random_generator;

// this one should be high quality, but is slightly slower than tausworthe
struct r250521_random_generator
{
  r250_random_generator r250;
  r521_random_generator r521;

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

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

  random_number_generator (uint32_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);
  }

  // return a number within the half-open interval [0..1[
  double operator ()()
  {
    return this->next () / (double)0x100000000ULL;
  }

  uint32_t get_u32 ();
  uint64_t get_u64 ();

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_random_generator> rand_gen;

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

extern rand_gen rndm, rmg_rndm;

#endif

Revision:	1.2
Committed:	Tue Jul 6 20:00:46 2010 UTC (13 years, 10 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.1:	+12 -0 lines
Log Message:	move layout stuff to it's own include file
#	Content
1	/*
2	* This file is part of Deliantra, the Roguelike Realtime MMORPG.
3	*
4	* Copyright (©) 2010 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	// P. L'Ecuyer, “Maximally Equidistributed Combined Tausworthe Generators”, Mathematics of Computation, 65, 213 (1996), 203–213.
29	// http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
30	// http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
31	struct tausworthe_random_generator
32	{
33	uint32_t state [4];
34
35	void seed (uint32_t seed);
36	uint32_t next ();
37	};
38
39	// Xorshift RNGs, George Marsaglia
40	// http://www.jstatsoft.org/v08/i14/paper
41	// this one is about 40% faster than the tausworthe one above (i.e. not much),
42	// despite the inlining, and has the issue of only creating 2**32-1 numbers.
43	// see also http://www.iro.umontreal.ca/~lecuyer/myftp/papers/xorshift.pdf
44	struct xorshift_random_generator
45	{
46	uint32_t x, y;
47
48	void seed (uint32_t seed)
49	{
50	x = seed \| 1;
51	y = x * 69069U;
52	}
53
54	uint32_t next ()
55	{
56	uint32_t t = x ^ (x << 10);
57	x = y;
58	y = y ^ (y >> 13) ^ t ^ (t >> 10);
59	return y;
60	}
61	};
62
63	template<typename T, int N, int k>
64	struct gfsr_random_generator
65	{
66	int i;
67	T x[N];
68
69	// rng must have same bitwidth as T
70	template<typename RNG>
71	void seed_rng (RNG rng)
72	{
73	i = N;
74
75	do
76	x [--i] = rng.next ();
77	while (i > sizeof (T) * 8);
78
79	T m = 1;
80
81	do
82	{
83	x [--i] = (rng.next () \| m) & ~(m - 1);
84	m <<= 1;
85	}
86	while (i);
87	}
88
89	// actually should subclass to gfsr32... :)
90	void seed (uint32_t seed)
91	{
92	xorshift_random_generator rng;
93
94	rng.seed (seed);
95	this->seed_rng (rng);
96	}
97
98	T next ()
99	{
100	int j = i + (k - N);
101
102	if (j < 0)
103	j += N;
104
105	T v = (x [i] ^= x [j]);
106
107	i = (i ? i : N) - 1;
108
109	return v;
110	}
111	};
112
113	// these are about 2-3 times faster than tausworthe, non-inlined,
114	// and likely of higher quality.
115	typedef gfsr_random_generator<uint32_t, 250, 103> r250_random_generator;
116	typedef gfsr_random_generator<uint32_t, 521, 168> r521_random_generator;
117
118	// freeciv uses this one, so it's good enough for us :)
119	typedef gfsr_random_generator<uint32_t, 55, 24> freeciv_random_generator;
120
121	// this one should be high quality, but is slightly slower than tausworthe
122	struct r250521_random_generator
123	{
124	r250_random_generator r250;
125	r521_random_generator r521;
126
127	void seed (uint32_t seed);
128	uint32_t next ();
129	};
130
131	// this is actually an adaptor that provides different types
132	// of random numbers.
133	template<class generator>
134	struct random_number_generator : generator
135	{
136	random_number_generator ()
137	{
138	}
139
140	random_number_generator (uint32_t seed)
141	{
142	this->seed (seed);
143	}
144
145	// uniform distribution, [0 .. num - 1]
146	uint32_t operator ()(uint32_t num)
147	{
148	return !is_constant (num) ? get_range (num) // non-constant
149	: num & (num - 1) ? (this->next () * (uint64_t)num) >> 32U // constant, non-power-of-two
150	: this->next () & (num - 1); // constant, power-of-two
151	}
152
153	// return a number within the closed interval [min .. max], max can be >, < or == min.
154	int operator () (int r_min, int r_max)
155	{
156	return is_constant (r_min <= r_max) && r_min <= r_max
157	? r_min + operator ()(r_max - r_min + 1)
158	: get_range (r_min, r_max);
159	}
160
161	// return a number within the half-open interval [0..1[
162	double operator ()()
163	{
164	return this->next () / (double)0x100000000ULL;
165	}
166
167	uint32_t get_u32 ();
168	uint64_t get_u64 ();
169
170	protected:
171	uint32_t get_range (uint32_t r_max);
172	int get_range (int r_min, int r_max);
173	};
174
175	// the default rng used in the game
176	typedef random_number_generator<freeciv_random_generator> rand_gen;
177
178	// used when we often seed
179	typedef random_number_generator<tausworthe_random_generator> seedable_rand_gen;
180
181	extern rand_gen rndm, rmg_rndm;
182
183	#endif
184