X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Frkiss.h;h=23bd614e5ced789619dcaa1023c84f7fa4556ce7;hb=f14cd1bb89d080f36a11df3c90f15da881c599df;hp=13f0640765a1ba42f23413ecc65b4cfe3bf22dc8;hpb=8fb16df70e032c782b6bf81b211e8dab1724a7dc;p=stockfish
diff --git a/src/rkiss.h b/src/rkiss.h
index 13f06407..23bd614e 100644
--- a/src/rkiss.h
+++ b/src/rkiss.h
@@ -1,23 +1,14 @@
-/** *********************************************************************** **
- ** A small "keep it simple and stupid" RNG with some fancy merits:
- **
- ** 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 save
- **
- ** (c) Heinz van Saanen
-
- This file is free software: you can redistribute it and/or modify
+/*
+ Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+ Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+ Copyright (C) 2008-2014 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.
- This file is distributed in the hope that it will be useful,
+ 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.
@@ -25,58 +16,58 @@
You should have received a copy of the GNU General Public License
along with this program. If not, see .
- ** *********************************************************************** **/
+ 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.
+*/
-#if !defined(RKISS_H_INCLUDED)
+#ifndef RKISS_H_INCLUDED
#define RKISS_H_INCLUDED
-
-////
-//// Includes
-////
-
-#include
-#include
-
#include "types.h"
-
-////
-//// Types
-////
+/// 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
- struct S { uint64_t a, b, c, d; } s;
-
- // Return 64 bit unsigned integer in between [0,2^64-1]
- uint64_t rand64() {
+ uint64_t a, b, c, d;
- const uint64_t
- e = s.a - ((s.b << 7) | (s.b >> 57));
- s.a = s.b ^ ((s.c << 13) | (s.c >> 51));
- s.b = s.c + ((s.d << 37) | (s.d >> 27));
- s.c = s.d + e;
- return s.d = e + s.a;
- }
+ uint64_t rotate(uint64_t x, uint64_t k) const {
+ return (x << k) | (x >> (64 - k));
+ }
- // Init seed and scramble a few rounds
- void raninit(uint64_t seed) {
+ uint64_t rand64() {
- s.a = 0xf1ea5eed;
- s.b = s.c = s.d = seed;
- for (uint64_t i = 0; i < 8; i++)
- rand64();
- }
+ const uint64_t e = a - rotate(b, 7);
+ a = b ^ rotate(c, 13);
+ b = c + rotate(d, 37);
+ c = d + e;
+ return d = e + a;
+ }
public:
- // Instance seed random or implicite
- RKISS() { ::srand(uint32_t(time(NULL))); raninit(uint64_t(::rand())); }
+ RKISS(int seed = 73) {
+
+ a = 0xF1EA5EED, b = c = d = 0xD4E12C77;
+
+ for (int i = 0; i < seed; ++i) // Scramble a few rounds
+ rand64();
+ }
- // Return random number of type T (must be castable from uint64_t)
- template
- T rand() { return T(rand64()); }
+ template T rand() { return T(rand64()); }
};
-#endif // !defined(RKISS_H_INCLUDED)
+#endif // #ifndef RKISS_H_INCLUDED