X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Frkiss.h;h=f3468db4e0f056edede0914c5a9d7cde72ea0bba;hp=ffcaf35a4752db1112c49841bfbf9cdaeba75cd8;hb=c014444f09ace05e908909d9c5c60127e998b538;hpb=549b5c478f0f455186945033559c4affe8f940ed

diff --git a/src/rkiss.h b/src/rkiss.h
index ffcaf35a..f3468db4 100644
--- a/src/rkiss.h
+++ b/src/rkiss.h
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
+  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
@@ -45,15 +45,15 @@ class RKISS {
 
   uint64_t a, b, c, d;
 
-  uint64_t rotate(uint64_t x, uint64_t k) const {
+  uint64_t rotate_L(uint64_t x, unsigned k) const {
     return (x << k) | (x >> (64 - k));
   }
 
   uint64_t rand64() {
 
-    const uint64_t e = a - rotate(b,  7);
-    a = b ^ rotate(c, 13);
-    b = c + rotate(d, 37);
+    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;
   }
@@ -68,6 +68,14 @@ public:
   }
 
   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 // #ifndef RKISS_H_INCLUDED