/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
available under the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
- ** George Marsaglia invented the RNG-Kiss-family in the early 90's.
- ** This is a specific version that Heinz van Saanen derived and
- ** tested from some public domain code by Bob Jenkins:
- **
- ** Quite platform independent
- ** Passes ALL dieharder tests! Here *nix sys-rand() e.g. fails miserably:-)
- ** ~12 times faster than my *nix sys-rand()
- ** ~4 times faster than SSE2-version of Mersenne twister
- ** Average cycle length: ~2^126
- ** 64 bit seed
- ** Return doubles with a full 53 bit mantissa
- ** Thread safe
*/
#if !defined(RKISS_H_INCLUDED)
#include "types.h"
+/// RKISS is our pseudo random number generator (PRNG) used to compute hash keys.
+/// George Marsaglia invented the RNG-Kiss-family in the early 90's. This is a
+/// specific version that Heinz van Saanen derived from some public domain code
+/// by Bob Jenkins. Following the feature list, as tested by Heinz.
+///
+/// - Quite platform independent
+/// - Passes ALL dieharder tests! Here *nix sys-rand() e.g. fails miserably:-)
+/// - ~12 times faster than my *nix sys-rand()
+/// - ~4 times faster than SSE2-version of Mersenne twister
+/// - Average cycle length: ~2^126
+/// - 64 bit seed
+/// - Return doubles with a full 53 bit mantissa
+/// - Thread safe
+
class RKISS {
// Keep variables always together
return s.d = e + s.a;
}
- // Init seed and scramble a few rounds
- void raninit() {
+public:
+ RKISS(int seed = 73) {
s.a = 0xf1ea5eed;
s.b = s.c = s.d = 0xd4e12c77;
- for (int i = 0; i < 73; i++)
+ for (int i = 0; i < seed; i++) // Scramble a few rounds
rand64();
}
-public:
- RKISS() { raninit(); }
template<typename T> T rand() { return T(rand64()); }
};