Use Heinz's RKiss instead of marsenne

[stockfish] / src / rkiss.h

diff --git a/src/rkiss.h b/src/rkiss.h
new file mode 100644 (file)
index 0000000..6e94dc2
--- /dev/null
+++ b/src/rkiss.h
@@ -0,0 +1,77 @@
+/** *********************************************************************** **
+ ** 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
+  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/>.
+
+ ** *********************************************************************** **/
+
+#ifndef _RKISS_H_
+#define _RKISS_H_
+
+/** Includes **/
+#include <cstdlib>    // srand(), rand()
+#include <ctime>      // time()
+#include "types.h"    // (u)int8_t .. (u)int64_t
+
+
+/** Random class **/
+class RKISS {
+
+private:
+       // Keep variables always together
+       struct S { uint64_t a; uint64_t b; uint64_t c; uint64_t d; } s;
+
+       // Init seed and scramble a few rounds
+       void raninit ( uint64_t seed ) {
+               s.a = 0xf1ea5eed; s.b = s.c = s.d = seed;
+               for ( uint64_t i=0; i<8; i++ ) rand64();
+       }
+
+public:
+       // Instance seed random or implicite
+       RKISS() { ::srand ( (uint32_t)time(NULL) ); raninit ( (uint64_t)::rand() ); }
+       // RKISS( uint64_t s ) { raninit ( s ); }
+
+       // (Re)init seed
+       // void init ( uint64_t seed ) { raninit ( seed ); }
+
+       // Return 32 bit unsigned integer in between [0,2^32-1]
+       uint32_t rand32 () { return (uint32_t) rand64 (); }
+
+       // Return 64 bit unsigned integer in between [0,2^64-1]
+       uint64_t rand64 () {
+               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;
+       }
+
+       // Return double in between [0,1). Keep full 53 bit mantissa
+       // double frand () { return (int64_t)(rand64()>>11) * (1.0/(67108864.0*134217728.0)); }
+};
+
+// _RKISS_H_
+#endif