Add some tablebase positions to bench

[stockfish] / src / rkiss.h

diff --git a/src/rkiss.h b/src/rkiss.h
index 13f0640765a1ba42f23413ecc65b4cfe3bf22dc8..f3468db4e0f056edede0914c5a9d7cde72ea0bba 100644 (file)
--- 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 +16,66 @@
   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.
+*/
 
-#if !defined(RKISS_H_INCLUDED)
+#ifndef RKISS_H_INCLUDED
 #define RKISS_H_INCLUDED
 
-
-////
-//// Includes
-////
-
-#include <cstdlib>
-#include <ctime>
-
 #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_L(uint64_t x, unsigned 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_L(b,  7);
+    a = b ^ rotate_L(c, 13);
+    b = c + rotate_L(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();
+  }
+
+  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()); }
+  /// Special generator used to fast init magic numbers. Here the
+  /// trick is to rotate the randoms of a given quantity 's' known
+  /// to be optimal to quickly find a good magic candidate.
+  template<typename T> T magic_rand(int s) {
+    return rotate_L(rotate_L(rand<T>(), (s >> 0) & 0x3F) & rand<T>()
+                                      , (s >> 6) & 0x3F) & rand<T>();
+  }
 };
 
-#endif // !defined(RKISS_H_INCLUDED)
+#endif // #ifndef RKISS_H_INCLUDED