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Make rkiss seed deterministic

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Search at fixed depth with one thread must be
reproducible so remove randomess from time().

Also better license description.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2010-11-07 12:33:17 +01:00
parent 8fb16df70e
commit 4cd53b68d0
1 changed files with 45 additions and 43 deletions
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88
src/rkiss.h
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@@ -1,4 +1,26 @@
/** *********************************************************************** ** /*
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
Stockfish is free software: you can redistribute it and/or modify
it under the terms of 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.
Stockfish 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 GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
This file is based on original code by Heinz van Saanen and is
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.
** A small "keep it simple and stupid" RNG with some fancy merits: ** A small "keep it simple and stupid" RNG with some fancy merits:
** **
** Quite platform independent ** Quite platform independent
@@ -8,24 +30,11 @@
** Average cycle length: ~2^126 ** Average cycle length: ~2^126
** 64 bit seed ** 64 bit seed
** Return doubles with a full 53 bit mantissa ** Return doubles with a full 53 bit mantissa
** Thread save ** Thread safe
** **
** (c) Heinz van Saanen ** (c) Heinz van Saanen
This file is free software: you can redistribute it and/or modify */
it under the terms of 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.
This file 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 GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
** *********************************************************************** **/
#if !defined(RKISS_H_INCLUDED) #if !defined(RKISS_H_INCLUDED)
#define RKISS_H_INCLUDED #define RKISS_H_INCLUDED
@@ -35,9 +44,6 @@
//// Includes //// Includes
//// ////
#include <cstdlib>
#include <ctime>
#include "types.h" #include "types.h"
@@ -47,36 +53,32 @@
class RKISS { class RKISS {
// Keep variables always together // Keep variables always together
struct S { uint64_t a, b, c, d; } s; struct S { uint64_t a, b, c, d; } s;
// Return 64 bit unsigned integer in between [0,2^64-1] // Return 64 bit unsigned integer in between [0,2^64-1]
uint64_t rand64() { uint64_t rand64() {
const uint64_t const uint64_t
e = s.a - ((s.b << 7) | (s.b >> 57)); e = s.a - ((s.b << 7) | (s.b >> 57));
s.a = s.b ^ ((s.c << 13) | (s.c >> 51)); s.a = s.b ^ ((s.c << 13) | (s.c >> 51));
s.b = s.c + ((s.d << 37) | (s.d >> 27)); s.b = s.c + ((s.d << 37) | (s.d >> 27));
s.c = s.d + e; s.c = s.d + e;
return s.d = e + s.a; return s.d = e + s.a;
} }
// Init seed and scramble a few rounds // Init seed and scramble a few rounds
void raninit(uint64_t seed) { void raninit() {
s.a = 0xf1ea5eed; s.a = 0xf1ea5eed;
s.b = s.c = s.d = seed; s.b = s.c = s.d = 0xd4e12c77;
for (uint64_t i = 0; i < 8; i++) for (uint64_t i = 0; i < 73; i++)
rand64(); rand64();
} }
public: public:
// Instance seed random or implicite RKISS() { raninit(); }
RKISS() { ::srand(uint32_t(time(NULL))); raninit(uint64_t(::rand())); } template<typename T> T rand() { return T(rand64()); }
// Return random number of type T (must be castable from uint64_t)
template<typename T>
T rand() { return T(rand64()); }
}; };
#endif // !defined(RKISS_H_INCLUDED) #endif // !defined(RKISS_H_INCLUDED)