include/Geant4/G4QuickRand.hh

0001 //
0002 // ********************************************************************
0003 // * License and Disclaimer                                           *
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0024 // ********************************************************************
0025 //
0026 //
0027 //
0028 #ifndef G4QUICKRAND_HH
0029 #define G4QUICKRAND_HH
0030
0031 #include "G4Types.hh"
0032 #include <cstdint>
0033
0034 inline G4double G4QuickRand()
0035 {
0036   static const G4double f = 1. / 4294967296.;  // 2^-32
0037
0038   // Algorithm "xor" from p.4 of G.Marsaglia, "Xorshift RNGs"
0039   static G4ThreadLocal uint32_t y = 2463534242;
0040   uint32_t x                      = y;
0041   x ^= x << 13;
0042   x ^= x >> 17;
0043   x ^= x << 5;
0044   y = x;
0045   return x * f;
0046 }
0047
0048 #endif  // G4QUICKRAND_HH