[math] Have TRandom2/3::Rndm() delegate to operator()()

Avoids duplicating the Tausworthe/Mersenne Twister state-advance logic.
Rndm() now calls operator()() to get the raw integer and then scales it
to a double, keeping a single source of truth for the generator core.
The TAUSWORTHE macro is moved to file scope so RndmArray can still use it.

Author: medeirosdev

math/mathcore/src/TRandom2.cxx

@@ -26,6 +26,8 @@ The publications are available online at
 #include "TRandom2.h"
 #include "TUUID.h"
 
+#define TAUSWORTHE(s,a,b,c,d) (((s &c) <<d) & 0xffffffffUL ) ^ ((((s <<a) & 0xffffffffUL )^s) >>b)
+
 
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -53,17 +55,11 @@ TRandom2::~TRandom2()
 
 Double_t TRandom2::Rndm()
 {
-#define TAUSWORTHE(s,a,b,c,d) (((s &c) <<d) & 0xffffffffUL ) ^ ((((s <<a) & 0xffffffffUL )^s) >>b)
-
    // scale by 1./(Max<UINT> + 1) = 1./4294967296
    const double kScale = 2.3283064365386963e-10;    // range in 32 bit ( 1/(2**32)
 
-   fSeed  = TAUSWORTHE (fSeed, 13, 19, 4294967294UL, 12);
-   fSeed1 = TAUSWORTHE (fSeed1, 2, 25, 4294967288UL, 4);
-   fSeed2 = TAUSWORTHE (fSeed2, 3, 11, 4294967280UL, 17);
-
-   UInt_t iy = fSeed ^ fSeed1 ^ fSeed2;
-   if (iy) return  kScale*static_cast<Double_t>(iy);
+   UInt_t iy = operator()();
+   if (iy) return kScale * static_cast<Double_t>(iy);
    return Rndm();
 }
 

math/mathcore/src/TRandom3.cxx

@@ -106,42 +106,9 @@ TRandom3::~TRandom3()
 
 Double_t TRandom3::Rndm()
 {
-   UInt_t y;
-
-   const Int_t  kM = 397;
-   const Int_t  kN = 624;
-   const UInt_t kTemperingMaskB =  0x9d2c5680;
-   const UInt_t kTemperingMaskC =  0xefc60000;
-   const UInt_t kUpperMask =       0x80000000;
-   const UInt_t kLowerMask =       0x7fffffff;
-   const UInt_t kMatrixA =         0x9908b0df;
-
-   if (fCount624 >= kN) {
-      Int_t i;
-
-      for (i=0; i < kN-kM; i++) {
-         y = (fMt[i] & kUpperMask) | (fMt[i+1] & kLowerMask);
-         fMt[i] = fMt[i+kM] ^ (y >> 1) ^ ((y & 0x1) ? kMatrixA : 0x0);
-      }
-
-      for (   ; i < kN-1    ; i++) {
-         y = (fMt[i] & kUpperMask) | (fMt[i+1] & kLowerMask);
-         fMt[i] = fMt[i+kM-kN] ^ (y >> 1) ^ ((y & 0x1) ? kMatrixA : 0x0);
-      }
-
-      y = (fMt[kN-1] & kUpperMask) | (fMt[0] & kLowerMask);
-      fMt[kN-1] = fMt[kM-1] ^ (y >> 1) ^ ((y & 0x1) ? kMatrixA : 0x0);
-      fCount624 = 0;
-   }
-
-   y = fMt[fCount624++];
-   y ^=  (y >> 11);
-   y ^= ((y << 7 ) & kTemperingMaskB );
-   y ^= ((y << 15) & kTemperingMaskC );
-   y ^=  (y >> 18);
-
    // 2.3283064365386963e-10 == 1./(UINT_MAX+1UL)  -> then returned value cannot be = 1.0
-   if (y) return ( (Double_t) y * 2.3283064365386963e-10); // * Power(2,-32)
+   UInt_t y = operator()();
+   if (y) return ((Double_t) y * 2.3283064365386963e-10); // * Power(2,-32)
    return Rndm();
 }