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:
+ ** George Marsaglia invented the RNG-Kiss-family in the early 90's.
+ ** This is a specific version that Heinz van Saanen derived and
+ ** tested from some public domain code by Bob Jenkins:
**
** Quite platform independent
** Passes ALL dieharder tests! Here *nix sys-rand() e.g. fails miserably:-)
** 64 bit seed
** Return doubles with a full 53 bit mantissa
** Thread safe
- **
- ** (c) Heinz van Saanen
-
*/
#if !defined(RKISS_H_INCLUDED)
#define RKISS_H_INCLUDED
-
-////
-//// Includes
-////
-
#include "types.h"
-
-////
-//// Types
-////
-
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 rotate(uint64_t x, uint64_t k) const {
+ return (x << k) | (x >> (64 - k));
+ }
+
+ // 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;
+ const uint64_t
+ e = s.a - rotate(s.b, 7);
+ s.a = s.b ^ rotate(s.c, 13);
+ s.b = s.c + rotate(s.d, 37);
+ s.c = s.d + e;
+ return s.d = e + s.a;
}
// Init seed and scramble a few rounds
void raninit() {
- s.a = 0xf1ea5eed;
- s.b = s.c = s.d = 0xd4e12c77;
- for (uint64_t i = 0; i < 73; i++)
- rand64();
+ s.a = 0xf1ea5eed;
+ s.b = s.c = s.d = 0xd4e12c77;
+ for (int i = 0; i < 73; i++)
+ rand64();
}
public: